Every November, something predictable happens. The air gets colder, the heating clicks on, and within a week or two your skin starts sending complaints: tightness after washing, flaking around the nose, a dull grey cast, and that particular itch that shows up on the shins at night. It would be easy to file this under "winter skin" and reach for a heavier jar. But the discomfort isn't a mystery and it isn't a matter of your skin simply being "dry." It's a measurable series of physiological events — humidity gradients, lipid chemistry, and barrier proteins all responding to the environment around you.
Understanding what's actually happening changes what you do about it. So let's walk through the biology, then look at how to build a routine that works with it.
Your skin barrier is a brick wall with mortar made of fat
The outermost layer of your skin, the stratum corneum, is often described as a brick-and-mortar structure. The "bricks" are flattened, protein-rich cells called corneocytes. The "mortar" holding them together is a mix of intercellular lipids — ceramides, cholesterol, and free fatty acids. Ceramides alone make up roughly 47% of the stratum corneum lipids by weight.
This mortar is what keeps water in and keeps irritants, allergens, and microbes out. When it's intact, water diffuses through the skin at a slow, controlled rate. When it's disrupted — whether by harsh cleansers, mechanical stress, or the chemical changes cold weather triggers — water escapes faster, and outside substances get in more easily.
The measurable result is transepidermal water loss, or TEWL: the rate at which water vapor diffuses out through the stratum corneum. TEWL is the standard clinical index of barrier function precisely because it directly quantifies how leaky that wall has become.
What cold air and low humidity actually do
Two distinct environmental forces hit your skin at once in winter, and they work through different mechanisms.
The humidity gradient. Water vapor moves from areas of high concentration to low concentration. In summer, when relative humidity is high, that gradient between your skin's surface and the surrounding air is shallow. In winter, ambient humidity drops — outdoor air holds very little moisture when it's cold, and forced-air heating inside drops it further — so the gradient steepens. Water leaves your skin faster simply because there is dramatically less water in the air to push back against it. Winter is consistently associated with higher TEWL values for exactly this reason.
The temperature effect. Cold itself changes skin physiology. A 2016 review in the Journal of the European Academy of Dermatology and Venereology examined the mechanisms behind winter skin complaints and concluded that both low humidity and low temperatures lead to a general decrease in skin barrier function, with increased susceptibility to mechanical stress. The review noted that keratinocytes release pro-inflammatory cytokines and cortisol under these conditions, and dermal mast cell numbers increase — which is why winter skin becomes more reactive to irritants and allergens, not merely drier. This is why people with eczema and atopic dermatitis flare so reliably in winter: the barrier defect and the inflammatory response compound each other.
There's a regional wrinkle too. A biophysical study comparing the same women in late summer and winter found that barrier function was significantly impaired in winter on both the cheek and the forearm — but the seasonal difference was much larger on the face than on the forearm. Exposed facial skin, already thinner and subject to more environmental contact, becomes disproportionately irritable in winter even in otherwise healthy people.
Your lipids change composition, not just quantity
Here's where it gets more interesting than "you need more moisturiser."
Sebum production and surface lipid levels drop in winter. A year-long study of facial skin found that lower lipid production and reduced barrier function both occurred during the winter months, with sebum production lowest in winter and highest in autumn. Skin moisture in both acne and non-acne subjects was higher in summer and autumn compared to winter.
But beside the volume, the composition shifts. Research using mass spectrometry to profile ceramides in the stratum corneum across the seasons has found notable reductions in specific ceramide species — including the acylceramides CER and CER[EOH] and the ceramide classes CER[NH] and CER[AH] — in autumn and winter, with those differences most apparent in winter months. Crucially, lower ceramide levels correlated with elevated TEWL.
Other work tracked the ratio of CER linoleate to CER[EOS] oleate and found it dropped dramatically in winter. The ratio matters because acylceramides with linoleic acid are structurally critical to the lipid arrangement that makes the barrier work. It's not just that you have fewer lipids in winter; the lipids you have are organized less effectively.
There's a useful nuance here, though. One study of ceramide mass across body sites found ceramide levels slightly increased in winter at almost all sites compared to summer, reflecting seemingly enhanced keratinization. That seems to contradict the depletion findings — and it's a good reminder that "winter skin" isn't one uniform process. Barrier lipids are being turned over, redistributed, and enzymatically altered in several directions at once. What consistently emerges across the literature is the functional outcome: higher TEWL, lower hydration, more reactivity. The composition gets less efficient even as the biology scrambles to compensate.
Why indoor heating deserves part of the blame
It's worth separating the villain from the accomplice. Cold outdoor air is one thing. But the air inside your home and office in winter is often drier than the air outside — heating warms air without adding moisture, which lowers relative humidity substantially. You then spend eight hours sleeping and eight hours working in that environment.
Worse, when you come in from the cold, your skin temperature rises quickly. A study on ambient humidity and TEWL found the diffusion coefficient of the stratum corneum alters with changing humidity levels, and that TEWL shifted markedly across humidity ranges. Rapid temperature and humidity swings — cold dry outside, warm dry inside, hot shower, back outside — repeatedly stress a barrier that in summer would barely notice.
The behavioural traps winter sets for you
The environmental changes are only half the story. Winter reliably pushes people toward habits that make the problem worse:
Hotter water. Long hot showers feel wonderful when you're cold and dissolve the lipid mortar more effectively. The heat increases water loss and strips surface oils.
Harsher cleansing. When skin feels grimy and dry at the same time, the instinct is to scrub. Foaming cleansers formulated for oily teenage skin are the wrong tool on a winter barrier.
Over-exfoliation. Because winter skin looks dull and flaky, people reach for acids. But flaking from barrier disruption is not the same as flaking from dead cell accumulation. Exfoliating a compromised barrier removes the very cells trying to repair it and drives TEWL higher.
Under-applying sunscreen. UV still reaches you in winter, and the barrier you're trying to rebuild is also your antioxidant defence. Skipping SPF in December undermines the repair work you did in the morning.
Giving up on moisturiser when it stings. That sting is the sign you need a barrier-supportive product, not the sign you need to stop.
What the science says you should do
The strategy follows logically from the mechanisms.
- Reduce water loss before adding water. Occlusive and lipid-replenishing ingredients limit TEWL from the outside. If the mortar is damaged, supply lipids structurally similar to the ones that are missing.
- Then hydrate. Humectants like glycerin, hyaluronic acid, and panthenol pull water into the stratum corneum. But a humectant without a lipid layer on top can, in very dry air, draw moisture from deeper layers toward the surface and lose it. Humectant first, lipid over it.
- Support the barrier's antioxidant defence. Winter involves free radical exposure from UV, wind, and pollution alongside the lipid stress.
- Favour gentle cleansing. Preserve what lipids remain.
- Adapt, don't rebuild. You don't need a new routine. You need to shift the same routine's emphasis — swap a lightweight moisturiser for a lipid-rich one, drop exfoliation frequency, add a barrier cream at night.
Building a winter routine with REFORM Skincare
REFORM Skincare is a doctor-formulated cosmeceutical line, and its product range maps onto these mechanisms unusually cleanly. Here's what I'd recommend from their range, in the order you'd layer it.
Gentle Hydrating Crème Cleanser — The starting point. A cream cleanser respects the lipid mortar instead of stripping it, which matters more in winter than in any other season. If you've been using a foaming cleanser through summer, this is your seasonal switch. Keep the water lukewarm.
Vitamin B5 Gel — Your humectant layer. This is a fast-absorbing, silky gel built around panthenol (Vitamin B5), and it's the product in their range most directly aimed at replenishing hydration while supporting the barrier. Panthenol is also a soothing agent, which is relevant when the barrier is compromised and the skin is reactive. Apply to slightly damp skin so it has water to draw in. Because it's a water-based gel, it goes before anything oil-based.
Phyto Botanical Gel — An alternative or complement to the B5 Gel for those who want a glycerin-and-hyaluronic-acid hydrating layer. REFORM positions it for deep, lasting hydration, ideal for dry or dehydrated skin, with both humectants working to attract and retain moisture and reinforce the barrier. If your winter skin is dehydrated-feeling but you find heavier textures uncomfortable, this layered under a cream is a good combination.
Skin Barrier Repair Cream — The centrepiece of a winter routine. This is the one REFORM explicitly describes in winter terms: advanced barrier repair for visibly healthier, winter-resilient skin. It's developed by medical professionals for the driest skin, including eczema-prone skin, and it's formulated to restore compromised barriers and support long-term skin health. The mechanism is specific: olus oil, rich in skin-compatible lipids, replenishes essential fats that reinforce the barrier, while panthenol and Vitamin E provide soothing, anti-inflammatory, and antioxidant support. The stated goal is exactly the physiological target we've been discussing — reduce transepidermal water loss, enhance hydration, and strengthen the skin's ability to protect itself from environmental stressors. Use it as your last step at night, and in the morning on the areas that take the brunt: cheeks, around the nose, and any patches that crack.
Intensive Moisturiser — If you want a barrier-supportive cream for daily use that sits a step lighter than the Barrier Repair Cream, this is the workhorse. Non-greasy and fast-absorbing, it delivers both immediate and lasting hydration while supporting barrier repair. It's the right daytime option under makeup, with the Barrier Repair Cream reserved for evening or for the driest zones.
HYAL • Vitamin C + E Serum — The antioxidant layer. Winter still delivers UV, cold wind, and urban pollution, all of which generate free radicals against a barrier that's already under strain. An antioxidant serum pairing Vitamin C with Vitamin E and hyaluronic acid supports the skin's defence and adds hydration simultaneously. Apply in the morning after cleansing, before your moisturiser. As REFORM's own product page notes, don't forget your sunscreen — which brings us to the last step.
SPF 50+ Antioxidant Sunscreen — Non-negotiable, year-round. This one is enriched with antioxidants, humectants, and moisturising ingredients, so it also strengthens the barrier and boosts hydration while neutralising free radicals. Winter SPF protects the barrier you spent the night repairing.
For very dry, compromised, or eczema-prone skin, REFORM also offers a Dry Skin Complete Routine bundle that packages the products aimed at dehydration and dryness together — a reasonable way to avoid assembling the pieces individually if you're starting from scratch.
A day in the winter routine
Morning: Gentle Hydrating Crème Cleanser → Vitamin B5 Gel (or Phyto Botanical Gel) → HYAL • Vitamin C + E Serum → Intensive Moisturiser → SPF 50+ Antioxidant Sunscreen.
Evening: Gentle Hydrating Crème Cleanser → Vitamin B5 Gel (or Phyto Botanical Gel) → Skin Barrier Repair Cream.
If you're using Retinol 1% Creme, winter is the season to look at your frequency honestly. Retinoids accelerate cell turnover and can increase TEWL and sensitivity, and the environmental load in winter is already high. Many people do better on a reduced schedule in the cold months — or buffered over a layer of moisturiser — than cutting it out entirely. If your skin starts stinging with retinol in December but never does in June, that's the barrier talking, not the product failing.
Similarly, dial back any acid-based exfoliant — a Glycolic Acid Foaming Cleanser or Salicylic Acid Foaming Cleanser — to once or twice a week at most, or pause it entirely if your barrier is visibly compromised. Flaking from a damaged barrier does not resolve with exfoliation.
Five things to change today, beyond products
- Lower your shower temperature and shorten the time. Warm, not hot.
- Add humidity. A humidifier in the bedroom and living space directly reduces the gradient driving water out of your skin.
- Reapply moisturiser to your hands and any exposed skin after every hand wash and every re-entry from the cold. Repeated small applications beat one heroic one.
- Don't exfoliate a stingy, tight, flaky face. That flaking is damage, not debris.
- Drink water. Hydration status affects the water available to the stratum corneum, though it's a supporting factor rather than the main solution.
The takeaway
Winter-dry skin isn't dry skin in the ordinary sense. It's a barrier operating under a steeper humidity gradient, with a lipid mortar that has been chemically altered, in an environment — indoor and outdoor — that keeps pulling water out of it, while keratinocyte signalling drives inflammation that makes everything feel worse. The itch and the tightness are the outward signs of a real, measurable shift in barrier function.
The fix follows the mechanism: hold water in with skin-compatible lipids, add humectants underneath, support the barrier's antioxidant capacity, cleanse gently, protect with SPF, and give the whole system a break from aggressors. Products built around barrier lipids and panthenol — like REFORM's Skin Barrier Repair Cream and Vitamin B5 Gel — are aimed at precisely those targets, which is why they earn their place in a winter routine rather than just being an extra step.
Adjust the routine's emphasis rather than replacing it. Come March, you can switch back.
