濕疹護膚博客 Eczema Skin Care Blog

Why Hot, Humid Weather Sets Eczema Off

Summer troubles eczema from two directions at once. Heat itself widens blood vessels and revs up the itch nerves, so warm skin simply feels itchier. On top of that, sweat is mildly irritating: it is slightly acidic and salty, and it contains trace metals and proteins that can sting broken skin and trigger itch as it dries and concentrates on the surface. High humidity then stops sweat from evaporating, so it lingers on the skin far longer than it should, keeping the irritation going. Damp, warm skin folds — behind the knees, the elbow creases, the neck — also become the perfect breeding ground for the bacteria and yeast that thrive during a flare.

Traditional Chinese Medicine reads this summer pattern as 濕熱 (damp-heat): the combination of external humidity and internal heat that it has long linked to red, oozing, intensely itchy skin. It is a neat description of exactly what a Hong Kong summer does to eczema-prone skin, and it points to the same practical goal that modern advice reaches — keep the skin cool, clean and dry, and don't let heat and dampness accumulate.

Manage Sweat Before It Manages You

You cannot — and should not — stop sweating; it is how the body cools itself. The goal is to stop sweat from sitting on the skin. After exercise, a hot commute, or any time you have worked up a sweat, rinse off with cool or lukewarm water as soon as you can, or at least gently pat the area with a damp cloth and a soft towel. Never let sweat dry on its own on affected skin, and never rub hard — blot instead. Carrying a small towel and a change of light cotton top in summer makes this far easier. Try to exercise during the cooler parts of the day, choose swimming or air-conditioned workouts over midday runs, and rinse and moisturise promptly afterwards, since both chlorine and salt water can dry the skin.

Air-Conditioning: Use It Wisely

Air-conditioning is one of summer's best tools for eczema, because keeping cool directly lowers itch and reduces sweating. But it has a catch: air-conditioners dry the air, and very dry indoor air pulls moisture out of the skin. The trick is balance. Set the temperature to comfortably cool rather than cold, avoid sitting directly in the path of the airflow, and if you spend long hours in heavy air-conditioning, run a small humidifier or place a bowl of water in the room to keep humidity in a comfortable middle range. Moisturise after coming indoors, and remember that the sharp swing between hot, humid outdoor air and cold, dry conditioned air can itself provoke itch — so give your skin a moment to adjust rather than going straight from a sweaty street into an icy shop or office.

Dress, Wash and Moisturise for the Season

Summer clothing should be loose, light-coloured and made of breathable natural fibres — cotton, or moisture-wicking blends designed for sport — so that air moves and sweat can escape rather than being trapped against the skin. Avoid tight synthetics and heavy seams that rub in the heat. In the bathroom, resist the temptation of long hot showers; they feel good for a moment but strip the skin's natural oils and leave it drier and itchier. Keep showers short and lukewarm, use a gentle fragrance-free cleanser only where needed, and pat — never rub — dry. Then moisturise within a few minutes, while the skin is still slightly damp, to lock water in. In summer many people prefer a lighter lotion or gel-cream by day and a richer cream at night, which feels less heavy in the heat while still protecting the barrier. A short, cool-to-lukewarm herbal soak such as Eczema Clear (濕疹清) can fit naturally into this routine, helping to rinse away sweat and soothe itchy, damp-heat-prone skin at the end of a hot day.

Finally, watch for the signs that summer eczema has tipped over into something needing more help: skin that is weeping, crusting golden-yellow, spreading fast, or painful and hot may be infected and warrants a doctor's visit. Managed sensibly, though, most summer flares can be kept in check — the season simply asks you to be a little more deliberate about staying cool, dry and moisturised. This article is general information and not a substitute for personalised medical advice.

Itch Is Not 'Mild Pain': The Skin's Dedicated Itch Wiring

For a long time itch was thought to be simply a weak version of pain, travelling along the same nerves. Neuroscience has shown this is wrong. The skin contains a specialised population of sensory nerve fibres — very fine, unmyelinated C-fibres — that are dedicated to signalling itch rather than pain. These fibres carry their own molecular receptors and are tuned to a distinct set of 'itch molecules'. When triggered, they send a signal up the spinal cord to the brain, which registers it not as 'hurt' but as the specific, maddening urge to scratch. Pain and itch even produce opposite behaviours: pain makes us withdraw, while itch makes us reach in and scratch. This is why scratching, which produces a mild pain sensation, can briefly mask an itch — the two systems partly cancel each other out.

Crucially, eczema itch is largely not driven by histamine — which is why ordinary antihistamines so often disappoint people with eczema. The itch of a mosquito bite or hives is histamine-driven and responds to antihistamines, but chronic eczema itch runs mostly along a separate, non-histamine pathway. Recognising that eczema uses its own itch wiring was a turning point: it redirected research away from histamine and towards the real messengers involved — the signals the immune system uses to speak directly to these nerves.

IL-31, the 'Itch Cytokine': How the Immune System Talks to Nerves

One of the most important discoveries in eczema research is a signalling molecule called interleukin-31 (IL-31), nicknamed the 'itch cytokine'. It is released by a type of immune cell (Th2 cells) that is overactive in eczema. Remarkably, the itch-sensing nerve fibres in the skin carry receptors for IL-31 — meaning the immune system can, in effect, reach out and press the itch button on the nerves directly. In experiments, IL-31 provokes intense, sustained itch, and people with more severe eczema tend to have higher levels of it. This was landmark evidence that in eczema the immune system and the nervous system are not separate systems reacting side by side, but are wired together in direct conversation.

IL-31 is not alone. Other immune signals such as TSLP (thymic stromal lymphopoietin), released by stressed and damaged skin cells, also act directly on sensory nerves to generate itch, while the enzymes and toxins produced during a flare can activate itch receptors too. Together these findings paint a picture of a barrier that, once breached, releases a cascade of molecules that light up the itch nerves — which is exactly why repairing and protecting the barrier does more than prevent moisture loss; it reduces the chemical 'noise' that keeps the itch nerves firing in the first place.

A Sensitised Nervous System: When the Alarm Won't Reset

In long-standing eczema, the itch problem is not only in the skin — the nervous system itself changes. With constant stimulation, the itch nerves in chronically affected skin sprout and multiply, so the same area becomes more densely wired for itch. The nerves also lower their firing threshold, becoming so twitchy that gentle, normally harmless stimuli — a woollen jumper, a warm room, light sweat, even stress — can now set off itch. Neuroscientists call these two phenomena peripheral and central sensitisation: the volume knob on the itch circuit, from skin to spinal cord to brain, gets turned up and stays up. In some people the wiring becomes so scrambled that touch itself begins to register as itch, a state known as alloknesis.

This sensitised state is the neural engine of the itch-scratch cycle. Scratching relieves itch for a few seconds — partly by replacing it with mild pain, and partly by triggering the brain's reward system, which is why it feels so satisfying and can become almost compulsive. But scratching also damages the barrier, releases more itch-provoking molecules, and reinforces the very nerve pathways that generate itch, so the relief is always followed by a stronger rebound. This is also why stress and poor sleep make eczema itchier: the brain's emotional and reward circuits feed directly into the itch pathway. Understanding this loop reframes treatment — breaking the cycle means calming the nerves and protecting the skin at the same time, not simply willing oneself not to scratch.

The TCM View: Itch as 'Wind' Moving Through the Skin

Long before cytokines and nerve fibres could be studied, Traditional Chinese Medicine had its own vivid explanation for itch: 風 (wind). In TCM, wind is the pathogenic factor that moves, changes quickly, and travels from place to place — an apt metaphor for an itch that flits across the body, comes and goes without warning, and worsens with movement or warmth. The classical teaching that '諸癢屬風' (all itching belongs to wind) captures exactly the restless, migrating quality that modern science attributes to hyper-excitable, widely distributed itch nerves. TCM further distinguishes patterns such as wind-heat (風熱, red, hot, intensely itchy skin) and blood-deficiency generating wind (血虛生風, the dry, chronically itchy skin of long-standing disease), which map loosely onto the inflamed, acute flare and the sensitised, chronic-itch state that neuroscience now describes.

The two frameworks are not the same, and TCM's 'wind' should not be read as a literal description of nerves. But it is striking that a tradition working purely from careful observation arrived at a model of itch as something mobile, changeable, and deeply tied to the body's internal state — a model that sits comfortably beside the modern picture of an over-connected, over-excitable itch circuit shaped by immunity, stress, and sleep. Practically, the TCM emphasis on 'dispelling wind, clearing heat, and nourishing blood' translates into calming the skin, cooling inflammation, and restoring moisture — goals that overlap neatly with the aim of quieting sensitised itch nerves.

Calming the Nerves, Not Just the Rash

Seeing itch as a nerve problem as much as a skin problem changes day-to-day care. Because heat and dryness are among the most reliable triggers of sensitised itch nerves, keeping cool and well moisturised does double duty — a rich emollient both seals the barrier and lowers the chemical signals that fire the nerves. Cooling an itchy patch (a cool compress, or a moisturiser kept in the fridge) works partly because cold sensations travel on nerves that compete with and dampen itch signals, offering relief without the barrier damage of scratching. Keeping nails short, wearing soft cotton, avoiding overheating, and managing stress and sleep all reduce the input feeding an already over-excitable circuit. A gentle, lukewarm herbal soak such as Eczema Clear (濕疹清) can be part of a calming daily routine, soothing itchy skin without the hot water that revs the itch nerves up.

This neural understanding also explains why the newest medical treatments for moderate-to-severe eczema work the way they do: rather than broadly suppressing the immune system, several target the specific itch signals — including drugs that block IL-31 or the closely related pathways — quietening the conversation between immunity and nerves. If itch is severe, robs you of sleep, or does not settle with good skin care, it is worth discussing these options with a doctor, as effective itch-targeted treatments now exist. This article is general information and not a substitute for personalised medical advice.

The Skin Has Its Own 24-Hour Clock

The human body is governed by circadian rhythms — roughly 24-hour cycles set by a master clock in the brain and echoed by 'peripheral clocks' inside almost every organ, including the skin. Skin cells switch different genes on and off across the day: repair, cell division, and barrier maintenance are largely night-time jobs, while daytime is geared towards defence against sunlight and environmental stress. This is efficient in healthy skin, but it means the barrier is naturally at its most permeable in the evening and overnight — precisely when eczema-prone skin can least afford to lose more moisture. In other words, the night-time itch is written into our biology, not simply a matter of having 'nothing to distract us' after dark.

Cortisol, Temperature and Water Loss: The Overnight Perfect Storm

Several measurable changes converge after dark. First, cortisol — the body's own anti-inflammatory hormone — follows a strong daily rhythm, peaking in the morning and falling to its lowest point around midnight. With less of this natural brake, inflammation and itch are freer to flare overnight. Second, core body temperature drops as we prepare for sleep, but blood flow to the skin rises and the skin surface warms; this warmth and the accompanying release of inflammatory signals can intensify the sensation of itch. Third, trans-epidermal water loss — the rate at which the skin leaks moisture — peaks in the evening and overnight, so a barrier that is already impaired dries out faster just when repair is most needed.

Layered on top is the itch hormone histamine, whose levels and effect also tend to rise in the evening, and the simple fact that a warm bed, heavy bedding, and fewer daytime distractions all draw attention to sensations the busy day kept at bay. None of these factors is dramatic on its own, but together they create an overnight 'perfect storm' in which the itch threshold falls just as the skin becomes driest and least defended.

A Vicious Cycle: Lost Sleep Feeds the Next Day's Flare

The night-time itch is not just uncomfortable — it disrupts sleep, and poor sleep in turn worsens eczema. Studies consistently find that most people with moderate-to-severe eczema report disturbed sleep, whether from conscious scratching or from micro-arousals that fragment sleep without fully waking them. Scratching during light sleep, when we have little control over it, damages the barrier further and can introduce infection. And the consequences reach beyond the night: broken sleep raises stress hormones, heightens the perception of itch the following day, and impairs the immune regulation that keeps inflammation in check. The result is a self-reinforcing loop — itch disturbs sleep, and lost sleep amplifies the next day's itch.

The TCM View: The Organ Clock and the Restless Small Hours

Long before circadian genes were discovered, Traditional Chinese Medicine had mapped the body's daily rhythm in its 'organ clock' (子午流注), which assigns each two-hour period to a particular organ system. The hours between roughly 1am and 3am are traditionally the Liver's time, and 3am to 5am the Lung's — organ systems that TCM closely links to the skin, to the smooth flow of qi, and to 'wind' and heat that provoke itching. Waking in these small hours with a restless, itchy body is, in this framework, unsurprising. TCM has long described intense night-time itch in patterns such as blood deficiency generating wind (血虛生風) and internal heat disturbing the spirit (熱擾心神), the latter also explaining the restlessness and difficulty settling that so often accompany a flare. It is a striking example of an old observational tradition and modern chronobiology arriving at the same conclusion: the skin, and its itch, follow the clock.

Working With the Clock, Not Against It

Because the overnight dip is predictable, an evening routine can be timed to counter it. Keep the bedroom cool and well-ventilated, and choose light, breathable cotton bedding to blunt the warmth that fuels itch. Apply a generous emollient shortly before bed to shore up the barrier just as water loss peaks, and keep another within reach for the small hours. A short, lukewarm — never hot — evening soak can calm the skin before sleep; a gentle herbal soak such as Eczema Clear (濕疹清) can be part of this wind-down routine, helping to soothe itchy skin as the day ends. Keeping consistent sleep and wake times helps steady the circadian clock itself, while cotton gloves or kept-short nails limit the damage of any unconscious scratching. If night-time itch is severe, robs you of sleep night after night, or the skin shows signs of infection such as weeping, crusting, or spreading redness, see a doctor — persistent sleep loss is a signal that the eczema needs more than home care. This article is general information and not a substitute for personalised medical advice.

The Skin Microbiome: A Living Ecosystem on the Surface

Healthy skin is not a sterile barrier — it is a thriving ecosystem. Trillions of bacteria, fungi, and viruses, collectively called the skin microbiome, live on the surface and within pores and hair follicles. In a healthy person this community is remarkably diverse, and that diversity is protective. Beneficial residents such as Staphylococcus epidermidis and other coagulase-negative staphylococci occupy space, consume nutrients, and produce their own natural antibiotics (antimicrobial peptides) that keep harmful organisms in check. They also 'train' the skin's immune system and help reinforce the barrier. A balanced microbiome, in other words, is part of the skin's defence — not a threat to it.

When Balance Breaks: The Rise of Staphylococcus aureus

In eczema, this ecosystem tips out of balance — a state scientists call dysbiosis. Studies using genetic sequencing have shown that during a flare, microbial diversity on eczema-affected skin drops sharply, and one species, Staphylococcus aureus, comes to dominate. Research has found S. aureus on the skin of roughly 70% or more of people with atopic dermatitis, compared with only a small fraction of people with healthy skin, and its abundance tends to rise just before and during flares. As the protective, diverse community is crowded out, the very organisms that would normally hold S. aureus back are lost — allowing it to expand further.

Why does eczema-prone skin let this happen? A weakened skin barrier is central. In many people with eczema the barrier is leaky and its natural acidity is reduced, and the skin produces fewer of its own antimicrobial peptides. This creates conditions in which S. aureus thrives while friendly microbes struggle. Crucially, the relationship runs both ways: S. aureus does not merely take advantage of damaged skin — it actively damages it further, driving a self-reinforcing cycle.

How the Bacteria Drive the Itch-Scratch Cycle

Once dominant, S. aureus releases a range of toxins and enzymes that inflame the skin. Some of its toxins act as 'superantigens' that provoke an exaggerated immune response; others, such as delta-toxin, trigger the skin's mast cells to release inflammatory chemicals. The bacterium also produces enzymes (proteases) that break down the skin's protective proteins and lipids, weakening the barrier still further. The result is more redness, more oozing, and — importantly — more itch. Scratching then breaks the skin open, giving S. aureus even more territory to colonise and spreading it to new areas. This is the microbial engine behind the familiar itch-scratch cycle: barrier damage feeds bacterial overgrowth, which feeds inflammation and itch, which feeds more scratching and more barrier damage.

This microbial picture also explains some everyday observations. Weeping, crusted, golden-yellow patches and a distinctive smell often signal that S. aureus has overgrown or that a frank infection has set in. It is why doctors sometimes prescribe antibiotics for badly infected eczema — though, importantly, routine long-term antibiotics are not recommended, because they also kill beneficial microbes and can encourage resistance. The most sustainable strategy is not to sterilise the skin but to restore the conditions in which a healthy, diverse microbiome can re-establish itself.

The TCM View: Damp-Heat and the Environment for 'Pathogenic' Overgrowth

Long before microbes could be seen under a microscope, Traditional Chinese Medicine described weeping, red, itchy, malodorous skin in terms of 濕熱 (damp-heat) accumulating in the skin. In TCM thinking, an internal environment of damp-heat creates fertile ground for skin problems to flourish — a description that sits surprisingly comfortably alongside the modern idea of a disturbed skin surface providing a niche for S. aureus overgrowth. Rather than targeting a single organism, the traditional approach aims to 'clear heat, drain dampness, and dispel wind' so that the skin's environment becomes less hospitable to flares. Many herbs used in classical skin formulas have been found in laboratory studies to have antibacterial and anti-inflammatory properties, which may partly explain their traditional use — though this is an area still being researched, and herbal remedies are best seen as gentle supportive care rather than a replacement for medical treatment of infection.

What both perspectives share is a focus on the whole environment of the skin rather than a single villain. In practical terms, that means protecting and repairing the barrier, avoiding harsh soaps and hot water that strip protective oils, moisturising consistently to keep the skin supple, and using gentle cleansing. A mild herbal soak such as Eczema Clear (濕疹清) can be part of this supportive daily routine, helping to keep the skin clean and comfortable without aggressive scrubbing. The goal is to tilt the balance back towards a calm, diverse, resilient skin surface.

The Hormonal Shift: How Falling Oestrogen Changes the Skin

Oestrogen is one of the skin's most important supporting hormones. It helps maintain collagen, stimulates the production of natural oils (sebum) and skin-barrier lipids called ceramides, and helps the skin hold onto water. During perimenopause and menopause — typically between the ages of 45 and 55 — oestrogen levels decline substantially. Research suggests skin can lose up to around 30% of its collagen in the first five years after menopause, alongside reduced oil production and a thinner, drier outer layer. The practical result is a skin barrier that is weaker, less able to retain moisture, and more easily irritated.

A weakened barrier lets water escape more quickly (increased trans-epidermal water loss) and lets irritants in more easily. This is why women who have never had a skin problem may suddenly develop dry, itchy patches in midlife, while those with a history of childhood eczema may see it return after decades of quiet skin. Falling oestrogen also subtly shifts immune balance, and the disrupted sleep, hot flushes, and stress that often accompany menopause can heighten the perception of itch — creating an itch-scratch cycle that further damages the barrier.

Recognising Menopausal Eczema and 'Winter Itch'

The most common midlife skin pattern is asteatotic eczema (sometimes called eczema craquelé or 'winter itch'): dry, tight skin that develops a fine network of cracks resembling crazy paving or a dried riverbed, often on the shins, forearms, and flanks. It tends to worsen in winter, in low humidity, in air-conditioned environments, and after long, hot showers that strip the skin's already-reduced oils. Some women also experience a generalised itch with little visible rash, or a crawling 'formication' sensation on the skin.

It is worth remembering that not every midlife itch is menopausal eczema. Thyroid changes, iron deficiency, certain medications, and other conditions can all cause itchy skin around the same age. Itch that is severe, spreads over the whole body, persists despite good moisturising, or occurs with no rash at all deserves a medical assessment rather than self-management, so that other causes can be ruled out. But for the common picture of dry, cracked, seasonally worse skin, gentle barrier-focused care is the foundation of relief.

The TCM Perspective: Blood Deficiency and Dryness at Midlife

Traditional Chinese Medicine has long described the menopausal transition in terms of a natural decline in Kidney essence and a relative deficiency of Liver Blood and yin. When Blood is abundant, it nourishes and moistens the skin, keeping it supple; when Blood becomes deficient with age, the skin is no longer properly nourished and 'wind' and 'dryness' arise internally — a pattern known as 血虛風燥 (blood-deficiency generating wind and dryness). This classical description maps remarkably well onto the dry, flaky, intensely itchy, asteatotic skin so common after menopause. Where yin deficiency also generates internal heat, the skin may show added redness and a burning quality.

The TCM approach for this pattern focuses on nourishing Blood and yin from within, and gently moistening the skin from without. Dietary suggestions traditionally include Blood- and yin-nourishing foods such as black sesame, goji berries, red dates, tremella (snow fungus), and pears, while reducing very spicy, drying, or overly heating foods. Externally, the emphasis is on gentle, moistening care rather than harsh, drying washes — an approach that aligns closely with modern barrier-repair dermatology, even though the two traditions arrived at it by different routes.

A Gentle Daily Routine for Menopausal Skin

Because midlife skin is drier and more fragile, the guiding principle is 'less stripping, more sealing'. Keep baths and showers short and lukewarm rather than hot; use a fragrance-free, gentle cleanser only where needed, and skip soap on dry limbs; pat — don't rub — the skin dry; and apply a rich emollient within about three minutes of bathing, while the skin is still slightly damp, to lock in moisture. In dry or air-conditioned environments, a humidifier helps, as does choosing soft cotton over wool or synthetic fabrics next to the skin. A gentle herbal soak such as Eczema Clear (濕疹清) can be incorporated into the bathing routine to soothe dry, itchy skin as part of daily maintenance.

Diet and lifestyle support the skin from within: staying well hydrated, eating oily fish or other sources of omega-3 fatty acids, and managing stress and sleep all help. Some women find that hormone replacement therapy (HRT), prescribed for other menopausal symptoms, also improves skin dryness — but HRT is a broader medical decision that should be discussed individually with a doctor, not started for skin reasons alone. Seek medical advice if itch is severe or widespread, if there is itch without any rash, if skin shows signs of infection such as spreading redness, warmth, or pus, or if symptoms disrupt sleep. This article is general information and not a substitute for personalised medical advice.

Understanding Topical Corticosteroids: How They Work and Why They're Prescribed

Topical corticosteroids ('steroid creams') are the first-line medical treatment recommended by dermatologists worldwide for moderate to severe eczema flares. They work by binding to receptors inside skin cells and switching off the genes responsible for producing inflammatory chemicals, while switching on genes that calm the immune response. The practical effect is a rapid reduction in redness, swelling, and itching — often noticeable within two to three days of consistent use. Steroids are graded by potency, from mild (such as hydrocortisone 1%, suitable for the face and for infants) to very potent formulations reserved for thick, stubborn plaques on areas like the palms or soles.

Decades of clinical trials confirm that, used correctly, topical steroids are both effective and safe for short-term flare management. Dermatologists typically recommend applying a thin layer — measured using the 'fingertip unit' guide — once or twice daily for one to two weeks, then tapering frequency as the skin improves. Some patients are prescribed 'weekend therapy', where a mild steroid is applied twice a week on previously affected areas even after they clear, to prevent the flare from returning. Used within these guidelines, the risk of serious side effects from intermittent topical use is low.

The Real Risks: Skin Thinning, Withdrawal Reactions, and Over-Reliance

The risks of topical steroids are real but are dose- and duration-dependent, not inevitable. Prolonged daily use of potent steroids — especially on thin-skinned areas such as the face, eyelids, and groin, or in young children — can cause skin thinning (atrophy), stretch marks, visible blood vessels, and in rare cases mild suppression of the body's natural cortisol production if very large areas are treated continuously over months. This is why dermatologists emphasise potency-matching (using the mildest effective strength for sensitive areas) and tapering rather than abrupt long-term continuous use.

A more debated phenomenon is Topical Steroid Withdrawal (TSW), sometimes called 'red skin syndrome' — a rebound reaction reported by some patients after stopping long-term, high-frequency steroid use, characterised by intense burning, redness, and skin shedding that spreads beyond the original eczema sites. Dermatological bodies note that TSW appears to be uncommon and is associated mainly with prolonged misuse rather than correctly supervised short courses, but it has understandably fuelled 'steroid phobia' among many patients and parents. The clinical irony is that this fear can backfire: under-treating active inflammation out of fear of steroids often prolongs flares, increases the risk of skin infection from broken skin, and can ultimately require stronger treatment than if the flare had been controlled early and properly.

Where TCM and Herbal Soaks Fit In: A Complement, Not a Replacement

Traditional Chinese Medicine does not aim to replace corticosteroids during a severe, acute flare — when inflammation is intense, properly prescribed steroids remain the fastest way to bring symptoms under control and prevent secondary infection. Where TCM and herbal skin care play their strongest role is in the maintenance phase between flares, and as a gentle daily complement that supports the skin barrier while a steroid course is being tapered. Many classical Chinese herbs used in topical eczema formulations — such as 黃柏 (Phellodendron bark) and 苦參 (Sophora flavescens root) — have been studied for antimicrobial and anti-inflammatory properties that may help calm mild irritation and reduce the bacterial load on broken skin, lowering infection risk without the systemic effects of medication.

In practice, many patients in Hong Kong combine a dermatologist-prescribed steroid for active flares with a gentle herbal soak, such as Eczema Clear (濕疹清), used during the bathing routine on non-flare days to help calm residual redness and support the skin's recovery between treatments. This is an additive, not a competing, approach — but it is important to inform your dermatologist about any herbal products you are using, both so they can advise on suitability and so steroid tapering can be supervised properly rather than stopped abruptly based on fear alone.

Building an Integrated Plan: When to See a Dermatologist

Certain signs always warrant prompt medical attention rather than self-management: spreading redness with warmth or pus suggesting infection, fever, eczema that disrupts sleep for several consecutive nights, a flare that fails to improve after a week of appropriate over-the-counter care, or any sign of a possible steroid withdrawal reaction after stopping long-term use. In these cases, see a dermatologist before relying solely on natural remedies.

A sensible integrated plan, discussed with your doctor, generally looks like this: use the correct-strength steroid for the shortest effective period during an acute flare; moisturise generously every day regardless of flare status; introduce a gentle herbal soak as part of daily maintenance care once active inflammation has settled; and schedule a dermatology follow-up if flares are becoming more frequent or severe, so the overall plan can be reassessed. Neither Western medicine nor TCM has to be chosen exclusively — the strongest outcomes typically come from using each where it is genuinely most effective.

The Gut as an Immune Organ: Far More Than Digestion

Most people think of the gut as a digestive organ — a long tube that breaks down food and absorbs nutrients. In reality, it is one of the body's most sophisticated immune organs. The gastrointestinal tract houses roughly 70–80% of the body's total immune cells, and its inner lining — a single layer of epithelial cells only one cell thick — forms a critical barrier between the contents of the intestine and the bloodstream. This barrier is maintained partly by the trillions of microorganisms that inhabit the gut: bacteria, fungi, and viruses collectively known as the gut microbiome.

The gut microbiome does far more than aid digestion. It actively trains and calibrates the immune system, particularly in the first years of life, teaching immune cells to distinguish harmless substances from genuine threats. When this microbial community is diverse and balanced, the immune system is well-regulated. When it is disrupted — a state called dysbiosis — immune responses can become dysregulated, prone to overreaction, and more likely to generate the kind of chronic, low-level inflammation that underpins conditions like eczema, asthma, and inflammatory bowel disease.

Gut Dysbiosis and Eczema: The Research Evidence

The link between gut microbiome composition and eczema is now well-supported by clinical research. Multiple large cohort studies have shown that infants who go on to develop eczema have distinctly different gut microbiome profiles in the first months of life, even before any skin symptoms appear. Specifically, they tend to have lower levels of beneficial bacteria from the Lactobacillus and Bifidobacterium families, higher proportions of pro-inflammatory species, and reduced microbial diversity overall. The KOALA Birth Cohort Study, which followed over 2,000 children from birth, found that reduced gut microbiome diversity at one month of age was a significant predictor of eczema development by two years — independent of other known risk factors.

Probiotic research has provided further evidence of this link. A landmark 2008 meta-analysis in The Lancet, and subsequent reviews, found that probiotic supplementation — particularly with Lactobacillus rhamnosus GG — during the last trimester of pregnancy and the first six months of infancy reduced the risk of eczema development by approximately 20–30% in high-risk children. While effects vary across strains and populations, the consistent direction of this evidence supports the view that modulating the gut microbiome has a meaningful influence on skin immune responses — particularly the Th2 overactivation that drives eczema inflammation.

Intestinal Permeability, Short-Chain Fatty Acids, and the Skin Barrier

Two mechanisms help explain how gut health influences skin directly. The first is intestinal permeability — sometimes called 'leaky gut' in popular media. The gut's single-cell epithelial lining is held together by tight junction proteins. In a state of dysbiosis, the production of these proteins can be disrupted, creating microscopic gaps that allow bacterial fragments — in particular, lipopolysaccharides (LPS) from the outer walls of certain bacteria — to cross into the bloodstream. Once in circulation, LPS molecules trigger a low-grade systemic inflammatory response that can amplify the immune overreaction already occurring in eczema-prone skin.

The second mechanism involves short-chain fatty acids (SCFAs) — compounds produced when beneficial gut bacteria ferment dietary fibre. SCFAs, particularly butyrate, propionate, and acetate, serve as energy sources for gut epithelial cells, help maintain the integrity of the gut lining, and exert powerful anti-inflammatory effects systemically. They promote regulatory T-cell (Treg) activity — the immune cells responsible for keeping Th2 responses from running out of control — and have been shown in animal models to improve skin barrier function and reduce eczema-like inflammation. When the diet is low in fibre and beneficial bacteria are depleted, SCFA production falls, and the gut-skin protective axis weakens.

TCM's Spleen-Skin Connection: An Ancient Framework Validated by Modern Science

Long before microbiome science existed, Traditional Chinese Medicine had developed a detailed theory linking digestive health to skin conditions. In TCM, the Spleen (脾) is the central organ of digestion — responsible not just for breaking down food but for 'transforming and transporting' (運化) nutrients and body fluids. A healthy Spleen produces abundant qi and blood to nourish the skin and keep it supple. A weakened or overloaded Spleen fails to process dampness efficiently, allowing it to accumulate in the body, combine with heat, and surface on the skin as the classic damp-heat pattern of eczema: weeping, red, itchy lesions.

The parallels between TCM's Spleen theory and modern gut-skin axis research are striking. Where modern science identifies gut dysbiosis, leaky gut, and reduced SCFA production as drivers of systemic inflammation that aggravates eczema, TCM describes Spleen qi deficiency leading to dampness accumulation and disrupted fluid transformation — producing the same downstream outcome of skin inflammation. Both frameworks agree that dietary habits are central: processed foods, excessive cold and raw foods, sugar, and alcohol weaken the gut microbiome just as TCM says they damage the Spleen. Fermented foods, fibre-rich vegetables, and warm, easily digested meals support microbial diversity just as TCM prescribes for Spleen restoration.

This understanding has practical implications for eczema management. Addressing only the skin's surface — with creams, soaks, and topical treatments — handles the symptom but not the source. A complete approach combines external skin care (such as a gentle herbal soak like Eczema Clear 濕疹清 to calm surface inflammation and support the skin barrier) with internal attention to gut health through dietary changes and, where appropriate, probiotic support. This inside-out approach is, in essence, what TCM has always recommended — and what the gut-skin axis research is now beginning to quantify.

What Twin Studies Tell Us: The High Heritability of Eczema

Twin studies are one of the most powerful tools for separating the influence of genes from environment, because identical twins share virtually 100% of their DNA while fraternal twins share about 50%, just like ordinary siblings. When researchers compare how often both twins in a pair develop eczema, identical twins show a concordance rate of around 70-80%, compared with roughly 20-30% in fraternal twins. This large gap points to a strong genetic component — eczema is, in fact, one of the most heritable common skin conditions studied. Family history matters too: if one parent has eczema, asthma, or hay fever, a child's risk of developing eczema roughly doubles; if both parents are affected, the risk can climb above 50%.

Genetic research has identified dozens of regions across the genome linked to eczema risk, including a cluster of immune-regulating genes on chromosome 5q31 that controls cytokines such as IL-4, IL-13, and IL-5 — the same inflammatory messengers responsible for the redness and itching of a flare-up. Yet heritability is not the same as inevitability. Many people who carry these risk variants never develop eczema, while others without any known genetic markers do. This tells us that genes set a baseline susceptibility — a kind of inherited 'tendency' — but something else determines whether that tendency is ever expressed.

Epigenetics: How the Environment 'Switches' Genes On and Off

This is where epigenetics comes in — the study of chemical changes that turn genes on or off without altering the underlying DNA sequence itself. Think of your DNA as a piano and epigenetic marks as the sheet music: the instrument doesn't change, but which notes get played does. The most studied epigenetic mechanism, DNA methylation, adds small chemical tags to genes that can silence or activate them in response to a person's environment, diet, and experiences — particularly during pregnancy and early infancy, when these systems are still being calibrated.

A growing body of research links specific early-life exposures to epigenetic changes associated with eczema risk. Studies have found that maternal smoking during pregnancy, exposure to traffic-related air pollution, and disruption of the infant gut microbiome through early antibiotic use can all leave epigenetic 'marks' that increase the activity of Th2 inflammatory genes — the same pathway responsible for the itch-inducing cytokines mentioned earlier. Conversely, factors such as a diverse diet, exposure to a varied microbial environment in early childhood (the so-called 'hygiene hypothesis'), and breastfeeding have been associated with epigenetic patterns that appear more protective. In short: the genes you're born with set the stage, but the environment in your first months — even before birth — helps decide which genes take the spotlight.

TCM's Ancient Answer: 'Inherited Endowment' (稟賦) and the Theory of Constitution (體質學說)

Long before DNA was discovered, Traditional Chinese Medicine had already developed a framework for thinking about inherited susceptibility. TCM holds that at conception, a person receives 先天之精 (pre-natal essence) from their parents, which forms their 稟賦 — an innate constitutional endowment that shapes lifelong tendencies toward certain patterns of imbalance. Classical paediatric texts describe a condition called 胎毒 (literally 'fetal toxin' or 'fetal heat') — heat and dampness believed to be transmitted from mother to baby during pregnancy, manifesting after birth as 奶癬 (milk rash), the traditional name for infant eczema. While the language is centuries old, the underlying idea — that a child can inherit a predisposition toward a particular pattern of skin inflammation from their parents — closely echoes what modern genetics now describes in molecular terms.

Modern TCM constitution theory (中醫體質學說), developed from extensive clinical classification work, identifies nine basic body constitutions. Two of these — 濕熱質 (damp-heat constitution) and 特稟質 (special/allergic constitution) — are strongly associated with eczema, allergic rhinitis, and asthma. Importantly, TCM treats constitution not as a fixed life sentence but as something that can be gradually adjusted (調體) over months and years through diet, daily habits, and consistent herbal care — a philosophy that aligns remarkably well with the modern epigenetic finding that gene expression can shift in response to lifestyle and environment, even when the underlying DNA cannot be changed.

For families with a strong history of eczema, this convergence of old and new knowledge has a practical implication: starting gentle, consistent skin care early — rather than waiting for severe flare-ups — may help support a more favourable trajectory. A mild herbal soak such as Eczema Clear (濕疹清), used as part of a regular bathing routine for infants and children with a family history of eczema, works on the skin's surface to calm inflammation and support barrier recovery, complementing — not replacing — the broader lifestyle and dietary adjustments that TCM constitutional theory has long recommended.

The Skin Barrier: A 'Brick Wall' That Sometimes Has Cracks

Dermatologists often describe the outermost layer of skin — the stratum corneum — using a 'brick and mortar' model. The 'bricks' are flattened skin cells called corneocytes, and the 'mortar' is a lipid matrix made of ceramides, cholesterol, and free fatty acids. Together, this structure keeps water in and irritants, allergens, and bacteria out. In healthy skin, this wall is tightly sealed. In eczema-prone skin, gaps form between the bricks, allowing moisture to escape and unwanted substances to enter.

A key player in maintaining this wall is a protein called filaggrin, produced by the FLG gene. As skin cells mature, filaggrin breaks down into amino acids that form part of the skin's Natural Moisturising Factor (NMF) — a group of molecules that draw and hold water in the outer skin layer, while also keeping its surface mildly acidic (around pH 5), an environment that discourages harmful bacteria. Research has found that mutations in the FLG gene are present in roughly 20-30% of people with eczema, and in up to half of those with moderate-to-severe disease. Without enough filaggrin, the skin loses water faster — a measurable phenomenon called transepidermal water loss (TEWL) — and becomes more vulnerable to irritants.

The Immune System's Overreaction: Th2 Inflammation and the Itch-Scratch Cycle

When the skin barrier is compromised, the immune system steps in — sometimes too aggressively. Damaged skin cells release 'alarm' signals (including TSLP, IL-25, and IL-33) that activate a branch of the immune system known as the Th2 response. This triggers the release of inflammatory messengers called cytokines — particularly IL-4 and IL-13 — which cause redness, swelling, and itching. Ironically, these same cytokines further suppress filaggrin production, weakening the barrier even more and creating a self-reinforcing cycle of damage and inflammation.

This cycle has a behavioural component too: the itch-scratch cycle. Inflammatory cytokines lower the threshold at which nerve fibres in the skin signal 'itch' to the brain, making eczema-prone skin itch more easily and more intensely. Scratching then physically damages the barrier further, releasing more alarm signals and perpetuating inflammation. Research into the skin microbiome adds another layer: studies have found that Staphylococcus aureus colonises up to 90% of eczema lesions, compared with around 5% of healthy skin. This bacterium produces toxins that can directly trigger inflammation and worsen the itch-scratch cycle — which is one reason gentle, non-disruptive skin cleansing matters so much.

Where Modern Research Meets Ancient Theory: 'The Lung Governs the Skin' and Damp-Heat

Long before filaggrin or cytokines were discovered, Traditional Chinese Medicine described a similar relationship through the principle '肺主皮毛' — the Lung governs the skin and body hair. In TCM theory, the Lung disperses defensive qi (衛氣) to the body's surface, where it regulates the pores, controls sweating, and provides a protective layer against external pathogens. Modern research offers an interesting parallel: eczema, allergic rhinitis, and asthma frequently occur together in what is called the 'atopic march', suggesting that the skin and respiratory immune systems share underlying regulatory pathways — much as TCM long proposed a Lung-skin connection.

TCM also attributes eczema to '脾虛濕困' — Spleen deficiency leading to dampness accumulation, which combines with heat and surfaces as redness, weeping, and itching on the skin. The Spleen, in TCM, governs the transformation and transportation of fluids in the body. Modern science has its own version of this idea in the 'gut-skin axis' — a growing body of research showing that gut microbiome composition and digestive health influence systemic inflammation and skin barrier integrity, sometimes mirroring the damp-heat pattern TCM practitioners have observed for centuries.

This is where external herbal therapy fits in. A warm herbal soak — such as Eczema Clear (濕疹清) — works on multiple levels at once. The warm water itself improves local blood circulation (what TCM calls moving qi and blood, and what modern physiology recognises as enhanced microcirculation supporting tissue repair). The herbal compounds carry anti-inflammatory and mild antimicrobial properties that may help calm overactive immune signalling and reduce surface bacteria — without the harshness of medicated soaps that can strip the skin's lipid barrier and disrupt its microbiome balance further.

The Hormonal Connection: Why Women Experience Eczema Differently

Oestrogen and progesterone play a significant role in regulating immune responses and skin barrier function. When these hormones fluctuate — during the luteal phase of the menstrual cycle, during pregnancy, or at menopause — the skin's ability to retain moisture and fend off irritants can weaken. Many women notice eczema flare-ups in the week before their period, when oestrogen levels drop sharply. This is not coincidental: oestrogen suppresses inflammation, so lower levels can leave skin more reactive and prone to itching and redness.

From a Traditional Chinese Medicine (TCM) perspective, these hormonal patterns map onto the body's yin-yang cycle. The pre-menstrual phase corresponds to a relative deficiency of yin (cooling, moistening energy), which can allow damp-heat to rise and manifest on the skin. TCM practitioners often address women's eczema with formulas that nourish yin and blood as well as clear heat and dampness — targeting the root cause rather than just the surface symptoms.

Eczema During Pregnancy: What Changes and What to Use Safely

Pregnancy brings the most dramatic hormonal shift a woman's body can experience, and the effects on eczema are unpredictable. Roughly half of pregnant women with pre-existing eczema find their condition worsens, particularly in the first and second trimesters. The surge in progesterone, combined with the immune system's shift toward a Th2-dominant response (to protect the foetus), can tip the balance toward increased IgE-mediated reactions — exactly the mechanism that drives eczema flare-ups.

Safety concerns during pregnancy lead many women to avoid topical steroids — and rightfully so, as high-potency corticosteroids carry documented risks. This makes gentle, plant-based alternatives particularly valuable. A warm herbal soak using a registered formulation like Eczema Clear (濕疹清) can soothe inflamed skin externally without systemic absorption concerns. The key is to use lukewarm water (not hot, which worsens dilation and itching) and to keep soak sessions short — around 10 to 15 minutes — followed by gentle patting dry.

Beyond topical care, pregnant women should prioritise cotton clothing, avoid fragranced detergents, maintain a cool sleeping environment, and follow a diet low in heaty and spicy foods. Stress management also matters: anxiety and sleep disruption — both common in pregnancy — are well-known eczema triggers that compound hormonal effects.

Breastfeeding and Your Baby's Eczema: The Dietary Link

One of the most important — and least-discussed — aspects of infant eczema is the role of the breastfeeding mother's diet. Breast milk is not a neutral medium: it carries bioactive compounds, fatty acids, cytokines, and trace amounts of dietary proteins that directly influence the baby's immune development and skin health. When a nursing mother consumes foods that generate damp-heat in TCM terms — such as beef, shellfish, alcohol, spicy dishes, and deep-fried foods — these properties can transmit through breast milk and exacerbate the baby's eczema.

Conversely, a cooling diet — featuring foods like barley water (薏米水), winter melon, mung bean soup, and lotus root — can help reduce damp-heat in both the mother's body and the baby's via milk. Some mothers report noticeable improvements in their baby's skin within days of making dietary adjustments. This does not mean extreme elimination diets; rather, a mindful reduction of the most heat-generating foods can yield meaningful results without nutritional compromise.

The postpartum period also deserves attention. After delivery, many women in Hong Kong follow traditional confinement practices (坐月) that involve consuming large amounts of ginger, sesame oil, and organ meats to 'replenish' the body. While these have cultural value, they can significantly increase internal heat — and both the new mother's eczema and the breastfed baby's skin may suffer as a result. A balanced approach — moderate warming foods with adequate cooling counterweights — is generally better tolerated than extreme confinement diets.

What is Eczema?

Eczema (atopic dermatitis) is an inflammatory skin condition that disrupts the skin barrier function. In Traditional Chinese Medicine, eczema is often described as a manifestation of damp-heat.

Common Eczema Triggers

Eczema flare-ups are often caused by a combination of factors:

Environmental Factors

• Extreme temperatures and low humidity (especially in winter)
• Certain fabrics (wool, synthetic fibres)
• Irritating soaps and detergents
• Pollutants and allergens (pollen, dust mites)

Diet & Lifestyle

• Spicy foods and hot beverages
• High-sugar and processed foods
• Stress and sleep deprivation
• Prolonged moisture exposure

Skincare Habits

• Over-washing or bathing in hot water
• Using unsuitable skincare products
• Neglecting to moisturise the skin

Eczema Symptoms and Where They Appear

Eczema symptoms vary from person to person, but typically include:

• Intense itching (especially at night)
• Dry, sensitive skin
• Red or brownish patches
• Small blisters, weeping, or crusting
• Swelling and cracked skin

Eczema can appear on any body part but most commonly affects hands, feet, face, neck, and skin folds.

Practical Tips for Managing Eczema

1. Keep Skin Hydrated

Wash with warm water (not hot) and apply moisturiser immediately to lock in moisture.

2. Choose the Right Fabrics

Prioritise cotton and natural fibres; avoid wool and coarse synthetic materials.

3. Identify and Avoid Triggers

Keep track of which products, foods, or environmental conditions trigger your eczema, and avoid them when possible.

4. Manage Stress & Sleep

Adequate sleep and stress management techniques (meditation, gentle exercise) help reduce flare-ups.

5. Consider Traditional Approaches

Many find that Traditional Chinese Medicine approaches — particularly heat therapy and herbal remedies — help clear damp-heat and soothe itching.

The TCM View: Skin Reflects What's Inside

In Traditional Chinese Medicine, the skin is a reflection of the body's internal state. Eczema — characterised by redness, itching, and inflammation — is understood as a manifestation of excess damp-heat accumulating in the body. What we eat plays a direct role in either aggravating or calming this internal imbalance.

Foods to Reduce or Avoid

• Beef, goose, and shellfish — highly 'heaty' in TCM, known to intensify damp-heat
• Spicy and deep-fried foods — generate internal heat and worsen inflammation
• Eggs and dairy — common triggers for damp-heat accumulation
• Alcohol — produces dampness internally and should be minimised during flare-ups

Cooling Foods to Add More Of

• Winter melon and cucumber — clear heat and dampness effectively
• Mung beans — a classic TCM ingredient for clearing heat and detoxifying
• Lotus root and barley water — soothe the skin and digestion from within
• Plain congee with minimal seasoning — gentle on digestion during flare-ups

A Note for Breastfeeding Mothers

If your baby has eczema, your own diet matters too. Breastfeeding mothers should pay particular attention to reducing heaty and spicy foods, as these can pass through breast milk and aggravate the baby's damp-heat constitution. Simple dietary adjustments by the mother can often produce noticeable improvements in the baby's skin within days.

Why Do Babies Get Eczema?

In babies, the skin barrier is naturally thinner and more sensitive than in adults, making it more vulnerable to irritants, allergens, and moisture loss. TCM views childhood eczema as a reflection of inherited damp-heat constitution combined with external triggers such as heat, sweat, or dietary factors passed through breast milk.

Gentle Care Tips for Children with Eczema

• Bathe in lukewarm water for no more than 10 minutes using a fragrance-free, gentle wash
• Pat — never rub — skin dry immediately after bathing
• Apply a gentle moisturiser within 3 minutes of bathing to lock in hydration
• Dress your child in loose, breathable cotton clothing
• Keep bedroom cool and well-ventilated, especially in summer

Eczema Clear for Babies & Children

Ng Yau Chun's Eczema Clear (濕疹清) is gentle enough for use on babies and young children. Used as a diluted soak or wash on affected areas, it soothes itching, reduces redness, and supports skin recovery naturally — without steroids or harsh chemicals. It is also effective for nappy rash, making it a practical all-in-one solution for young families.

A Different Approach to Eczema

While modern treatments often focus on managing flare-ups with steroids or antihistamines, traditional Chinese medicine (TCM) takes a different approach: restoring balance from within. TCM teaches that eczema is often linked to internal heat, dampness, or a weakened immune response.

Why Herbal Soaks Work

Topical herbal soaks allow active botanical compounds to penetrate the skin directly at the source of inflammation. Unlike oral medication, there are no systemic side effects — the herbs work gently on the affected area, cooling heat, relieving itch, and supporting skin repair.

Safe for the Whole Family

One of the greatest benefits of herbal skin care is its gentle nature. Eczema Clear is suitable for adults, babies, and children — making it ideal for families dealing with eczema at any age.

What is Eczema?

Eczema (atopic dermatitis) is a chronic inflammatory skin condition characterized by dry, itchy, and inflamed skin. It is not contagious but can be persistent and recurring. In Traditional Chinese Medicine (TCM), eczema is often viewed as a result of an imbalance of damp-heat, blood deficiency, and wind in the body.

Common Triggers

• Dry skin and low humidity environments
• Sweat and heat — especially in tropical or warm climates
• Certain foods: dairy, eggs, nuts, wheat
• Synthetic fabrics and rough textures against the skin
• Stress and emotional upheaval
• Harsh soaps, detergents, and skincare products

Management Approach

Effective eczema management typically involves identifying and avoiding personal triggers, maintaining skin hydration, using appropriate topical treatments, and — in TCM — addressing the underlying internal imbalance through herbal soaks and dietary adjustments.

TCM's Approach to Skin Health

In Traditional Chinese Medicine, skin conditions are not treated as isolated problems but as reflections of the body's internal state. Treatment focuses on clearing heat, eliminating dampness, nourishing blood, and expelling wind.

Key Herbs in Eczema Clear

土荊皮 (Cortex Pseudolaricis)

Pseudolarix bark is one of the most well-studied Chinese herbs for skin fungal infections. It contains pseudolaric acids which have demonstrated significant antifungal activity.

大飛揚草 (Herba Euphorbiae Hirtae)

Asthma weed is widely used in traditional medicine across Asia for its anti-inflammatory, antimicrobial, and antihistamine properties.

Bathing & Skin Care Routine

• Use lukewarm (not hot) water for bathing — hot water strips natural oils
• Limit bath time to 10–15 minutes
• Use gentle, fragrance-free cleansers
• Pat (don't rub) skin dry with a soft towel
• Apply moisturizer within 3 minutes of bathing to lock in moisture

Diet & Lifestyle (TCM Perspective)

• Reduce intake of spicy, oily, and deep-fried foods which are considered 'heating' in TCM
• Increase cooling foods: cucumber, winter melon, mung beans, lotus root
• Stay well hydrated — drink adequate water daily
• Reduce alcohol, which generates damp-heat internally
• Manage stress through exercise, meditation, or other relaxation techniques

Clothing & Environment

• Wear loose, soft, cotton clothing — avoid wool and synthetics
• Keep indoor humidity between 45–55% to prevent skin dryness
• Wash new clothes before wearing to remove manufacturing chemicals
• Use fragrance-free laundry detergents