Seborrhoeic dermatitis: symptoms, causes and treatment

BAD says there is currently no cure and the aim is to improve or clear the skin; it may flare again after treatment stops. General measures include a gentle soap-free wash, a light moisturiser afterwards, non-comedogenic make-up, and the observation that research suggests fruit consumption may help reduce flares. Antifungal creams and shampoos containing clotrimazole, miconazole, ketoconazole or nystatin are commonly prescribed and BAD says they can safely be used on a long-term basis. Occasionally a short course of oral antifungal medicine may be suggested for widespread or resistant rash.

When the skin is inflamed, a mild topical corticosteroid may be used for short periods, as creams, gels, ointments or scalp lotions. Topical calcineurin inhibitors are steroid-free and safer for longer use, though BAD notes they are not licensed for seborrhoeic dermatitis. For thick scale a keratolytic, which may contain coconut oil and salicylic acid, can be used first to help other treatments penetrate. The NHS suggests anti-dandruff shampoo containing ketoconazole, coal tar or salicylic acid for dandruff, used for up to 4 weeks to see if it helps, trying more than one type if needed.

BAD describes how to use treatments by site. For the scalp, medicated shampoos containing zinc pyrithione, selenium sulphide or ketoconazole can be used regularly, massaged in and left for 5 to 10 minutes before rinsing; descaling products go on first and may be left for hours or overnight. For the body, wash affected areas with an antifungal shampoo, leaving it on for 5 minutes. For the ear canals, medicated ear drops may help, and cotton buds should not be used. For eyelids, clean between the lashes with a non-irritating eyelid cleanser. Once clear, continue an antifungal shampoo once or twice a week to reduce the chance of the rash returning. Babies' seborrhoeic dermatitis resolves by itself within a few months, and the adult treatments are not suitable for them.

Affected areas can be itchy, sore and sensitive with flaking skin, and some people have the rash without other symptoms. According to BAD the skin can look red, or lighter or darker than the surrounding skin, with yellow flaking on the surface, and it can affect one or two areas or be more widespread.

Common sites are the scalp, ranging from mild flaking to inflamed, scaly, sometimes weeping skin; the face, especially the eyebrows and the creases around the nose and cheeks; the eyelids, where it can cause red, swollen, flaky lids called seborrhoeic blepharitis; in and around the ears, where infected skin may ooze and crust and ear canal inflammation can block the ear; the front of the chest and between the shoulder blades, as well-defined round flat areas with yellow scale; and skin folds such as under the breasts, the groin, under the arms and abdominal folds, where skin can look pink and shiny with cracks.

• Scalp: dandruff to inflamed scaly patches.

• Face: eyebrows, sides of the nose, cheeks, eyelids.

• Ears: in the canal, the cup of the ear and behind it.

• Chest and upper back: well-defined round patches with yellow scale.

• Skin folds: pink, shiny, sometimes cracked skin.

The British Association of Dermatologists (BAD) explains that seborrhoeic means the rash affects the greasy, or sebaceous, skin zones such as the face, scalp, and the centre of the chest and back, while dermatitis means the skin is inflamed, red, itchy and flaky. It is slightly more common in men than women and occurs in babies, teenagers and adults, often between the ages of 30 and 40.

Dandruff is the scalp form and, according to BAD, is very common, affecting almost half of all adults regardless of age, ethnicity or gender. The NHS describes dandruff as a common skin condition that is not harmful and cannot be caught. Babies can develop a short-lived type, commonly called cradle cap or in the nappy area, which usually clears after a few months and is separate from the adult condition and from nappy rash.

The cause is thought to involve many factors and is still being researched. BAD says a harmless yeast called Malassezia lives on normal skin but is found in higher amounts in seborrhoeic dermatitis, and current thinking is that abnormalities in the skin barrier, together with increased sensitivity to oleic acid produced by the yeast, lead to inflammation. This yeast is not the same as the yeasts that cause thrush or those in foods. The NHS adds that dandruff is not caused by poor hygiene, although it may be more obvious if you do not wash your hair regularly.

Flares can be triggered by tiredness, stress and cold, dry weather. BAD says there may be a genetic susceptibility that combines with external factors, and that the condition is seen more often in people who are immunocompromised, such as people living with HIV, or who have neurological disease such as Parkinson's disease, though in most people it is not linked to any underlying illness.

The British Association of Dermatologists says that research suggests fruit consumption may help to reduce flares. The sources read do not describe a diet that treats the condition, so food changes should not replace antifungal and anti-inflammatory treatment.

BAD says the diagnosis is usually made by examining the rash, mostly in primary care, with referral to a dermatologist in some cases. Tests are not usually necessary. If it is severe or does not respond to treatment and the person is at risk of HIV, an HIV test may be recommended; skin scrapings can look for tinea (ringworm) fungus if scalp ringworm is suspected; and a skin biopsy may be suggested if there is doubt, since seborrhoeic dermatitis can be difficult to distinguish from other rashes.

The NHS suggests a GP can check your scalp for other skin conditions if you still have dandruff symptoms after using anti-dandruff shampoo for at least 4 weeks, if your dandruff is bad or your scalp very itchy, your scalp is red or swollen, or you have flaky, itchy patches on your face or elsewhere. Other conditions that can look similar include psoriasis, eczema, contact dermatitis and ringworm.

The NHS dandruff page lists conditions that can cause flaky skin, so it is worth seeing a GP if the pattern does not fit. Do not worry if you are unsure what is causing your dandruff; follow the advice and see a GP if things do not get better in a month.

The NHS says to see a GP if you still have dandruff symptoms after using anti-dandruff shampoo for at least 4 weeks, your dandruff is bad or your scalp is very itchy, your scalp is red or swollen, or you have flaky, itchy patches on your face or other parts of your body. BAD adds that referral to a dermatologist is considered when the diagnosis is uncertain or the rash is severe or does not respond to treatment.

Most people are managed by pharmacists and GPs. Referral to a dermatologist is for diagnostic doubt, severe or widespread disease, or poor response. Private dermatology appointments can offer faster review and sometimes a skin scraping or biopsy if the diagnosis is unclear.

Because the condition is long-term, the most useful thing is a clear maintenance plan: which shampoo or cream to use at the first sign of a flare, how long to continue, and when to stop steroids. If the rash is associated with weight loss, new neurological symptoms or other illness, tell the clinician.