The cold weather can often cause or exacerbate skin conditions. But pharmacists can play a key role in helping patients manage their symptoms, says Rod Tucker
The reduction in temperature and humidity associated with the colder months affect the skin’s barrier function leading to a number of skin problems. The skin barrier prevents entry of allergens, irritants and micro-organisms and avoids excessive water loss. It is achieved by the uppermost layer of the epidermis, the stratum corneum (SC). The layer consists of between 10 and 30 stacked sheets of corneocytes embedded in a lipid-enriched lamellae.
This structure is analogous to a brick wall, with the corneocyte ‘bricks’ surrounded by a lipid lamellae ‘mortar’. The stacked corneocyte sheets are connected via corneodesmosomes, analogous to the steel rods within reinforced concrete, and provide tensile strength (ie resistance to shearing forces) to the skin. The SC cells are replaced every 28 days, with the rate of production of new cells, balanced by the desquamation (shedding) of old cells.
To remain soft and flexible the skin requires between 10-15% of water, which derives from the lower levels of the epidermis and is maintained by the presence of water-binding molecules (humectants) – such as lactic acid, urea, glycerol and hyaluronic acid within the corneocytes – which are collectively referred to as ‘natural moisturising factor’ (NMF). The barrier is further enhanced by a hydrolipidic film on the skin surface, which comprises sweat, sebum and water.
Cold air extracts moisture from the skin, leading to both reduced hydration and corneodesmosome degradation. The skin loses elasticity, becomes more fragile and there is an increase in the production of inflammatory mediators. Moreover, the dry air in centrally heated homes further reduces skin hydration.
Common winter skin conditions
Dry skin (xerosis)
If the skin’s water content drops below 10%, the enzymes responsible for corneocyte desquamation no longer function properly. The corneocytes shrink reducing levels of NMF and the lipid lamellae appears broken (analogous to crumbling mortar in an old brick wall). These will create breaches in the skin’s barrier, allowing for greater water loss.
Clinically, xerotic skin appears rough and flaky, with white patches (which represent adherent corneocytes due to reduced desquamation) that is both uncomfortable and pruritic. Dry skin is commonly seen on the lower legs, the trunk, forearms, hands and face. The feet are normally less prone to dryness, being protected by socks and tights, but dryness can be problem for those who walk barefoot or wear sandals.
Left untreated, xerotic skin becomes red, dull and rough, and ultimately starts to crack. These cracks deteriorate over time and can bleed, providing an entry portal for irritants and bacteria that can lead to infections.
Although dry skin can affect people of all ages, it is most common in older patients. Older skin has fewer sebaceous and sweat glands, and cells are lost at a greater rate than they are replaced. The end result is thinner skin with a reduced capacity to hold water.
Asteatotic eczema is common in the elderly on the lower legs and shins. Moreover, fissures can develop in the skin leading to ruptured dermal capillaries and resulting in bleeding. Asteatotic eczema occurs through excessive water loss from the skin and is worse in winter as older people spend more time in overheated, dry rooms, or sitting too close to fires or radiators. A further aggravating factor is excessive washing with soaps or detergents.
Management of xerosis and asteatotic eczema
Avoidance of soaps or detergents and the use of emollients will normally resolve both xerosis and asteatotic eczema. Bathing in hot water with soaps strips away the skin’s natural oils, provoking additional xerosis.
Washing in warm – rather than hot – water with added emollients will clean the skin and spare the skin’s natural oils. Emollients should be applied to the skin within a few minutes of bathing or showering because this traps surface moisture on the skin, leading to rehydration. When applying an emollient, it is not necessary to rub into the skin until it disappears. Simply dotting the product onto the skin and spreading in a downward stroking motion is sufficient.
Ointment-based emollients are more occlusive and provide greater hydration but are less cosmetically appealing. Alternatively, creams that contain a humectant provide a similar degree of hydration and are more aesthetically pleasing.
Xerosis can also be improved with a humidifier that increases the moisture content in the air.
If avoidance of soaps and greater emollient use fail to improve xerosis and asteatotic eczema, or if the skin starts to bleed or exhibit signs of infection (ie inflamed and feeling hot), patients should be referred to the GP.
Both adults and children with eczema often notice that their condition worsens during the colder months. Avoidance of soaps and increasing emollient use will combat the dryness. Patients should use at least 500g of emollient per week and apply it all over their skin, and even consider changing to a more occlusive product during the colder months.
When these measures are ineffective, patients should be referred to their GP.
Emollients have an important role in psoriasis, especially in winter by hydrating plaques. This prevents plaques from cracking, which can be very painful and lead to bleeding. Emollients are best applied 30 minutes before any active topical therapies and should also be used for washing and bathing.
This condition is generally worse in winter and presents as flaky, pruritic skin on the scalp (dandruff) and along the hairline. Scaling and inflammation are seen on the eyebrows, cheeks and sides of the nose with oval, pink and scaling patches on the chest and back.
Seborrheoic dermatitis is thought to be caused by an abnormal inflammatory reaction to a commensal yeast called Malassezia.
Cases affecting the scalp can be treated with shampoos containing coal-tar (eg T-Gel) or the antifungal agent ketoconazole (Nizoral). The facial inflammation can be managed with over-the-counter topical antifungals such as clotrimazole and ketoconazole.
Gusty winds during the winter and the dry air in overheated rooms cause the skin of patients with rosacea to become more sensitive. The use of scarves or ski masks may help outdoors in cold winds. Although hot soups and drinks are tempting in the colder weather, these should be avoided or at least left to cool off before drinking, particularly if certain foods are a known trigger.
Other skin conditions seen during the winter months
Also known as perniosis, chilblains are local, inflammatory lesions induced by cold exposure and appear on the fingers, toes, nose and ears as oedematous, red/purple papules, plaques or even nodules. Chilblains are more common in children, older people and women and produce a burning and itching sensation that is much worse upon entering a warm room.
During cold weather, the drop in temperature causes vasoconstriction and, once the skin is exposed to heat, the surface blood vessels dilate. Chilblains are thought to rise when this dilation occurs too quickly, causing blood to leak into the surrounding tissue, leading to the typical symptoms of swelling, erythema and pruritis.
Acute chilblains will normally resolve without treatment after three weeks provided patients avoid further exposure to the cold. However, if they observe any further swelling or formation of pus and feel unwell, a GP referral is required.
The lips are composed of soft tissue but lack sebaceous or sweat glands. The epithelium lip layer is very thin and exposure to cold wind leads to dryness and the skin becomes tight and starts to crack.
The regular application of a lip balm containing petroleum jelly or beeswax helps to trap moisture and close any cracks on the lip surface. Use of a scarf or mask outside in cold weather will also help.
If the lips appear red and sore despite treatment, a GP referral is required.
Rod Tucker is a community pharmacist