Dandruff: what it is, causes and how to treat it

The NHS says to use an anti-dandruff shampoo. Several types can be bought from pharmacies or supermarkets, and it suggests looking for one that contains one or more of ketoconazole, coal tar or salicylic acid. A pharmacist can tell you how to use the shampoo.

Use the shampoo for up to 4 weeks to see if your dandruff gets better. You might need to try more than one type to find one that works for you.

The British Association of Dermatologists, writing about seborrhoeic dermatitis of the scalp (the medical name for dandruff), says there is no cure but the aim of treatment is to improve or clear the skin, and that it can flare up again when treatment is stopped. It describes antifungal shampoos and creams as commonly used and safe on a long-term basis, and says keratolytic treatments containing ingredients such as salicylic acid can help remove thick scale.

Dandruff causes white flakes of skin to appear on the scalp and in the hair. The NHS says the flakes are often more noticeable in darker hair and when they fall from the scalp onto your shoulders, and that your scalp may also feel dry and itchy.

The British Association of Dermatologists explains that dandruff is the mild form of seborrhoeic dermatitis of the scalp, a very common condition in which the skin is inflamed, red, itchy and flaky. It ranges from mild flaking to inflamed skin with more scale.

No. The NHS says dandruff is not harmful and you cannot catch it. The yeast involved is already a natural part of the skin. The British Association of Dermatologists adds that the yeast involved is not the same as the yeasts that cause thrush or those present in foods.

The NHS says dandruff is not caused by poor hygiene, although it may be more obvious if you do not wash your hair regularly. It may be caused by different things, including a type of yeast that naturally lives on your skin, and skin conditions such as eczema. Stress and cold weather may also make it worse.

The British Association of Dermatologists says the cause of seborrhoeic dermatitis is thought to involve many factors. A harmless yeast called Malassezia is present on normal skin but is found in higher amounts in the condition, and abnormalities in the skin barrier and sensitivity to substances the yeast produces are thought to cause inflammation. Flares can be triggered by tiredness, stress and cold, dry weather, and there may be a genetic susceptibility. It occurs more frequently in people with weakened immune systems or neurological conditions such as Parkinson’s disease, but in most people it is not linked to an underlying illness.

Flaking on the scalp can have other causes. The NHS gives this guide to symptoms and possible causes, and says not to worry if you are not sure: follow the advice and see a GP if things do not get better in a month.

Dandruff is not usually serious, but the NHS says that if symptoms last a long time or become painful you may need medical help. See a GP if you still have 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.

The GP can check your scalp for skin conditions that could be causing it. The British Association of Dermatologists says the diagnosis is usually made by examining the rash, and that a dermatologist referral or skin scrapings may be needed if ringworm of the scalp is suspected.

Babies can get a short-lived type of seborrhoeic dermatitis on the scalp, commonly called cradle cap. The British Association of Dermatologists says it usually clears after a few months and, if there are no symptoms, may not need treatment. The NHS describes cradle cap as greasy, yellowish crusts on a baby’s scalp, eyebrows and nappy area.

Most dandruff is managed through a pharmacist and shop-bought shampoo. Prescription antifungal or mild steroid treatments come through a GP; dermatologists on the NHS or privately deal with stubborn or widespread cases. Private skin clinics may offer quicker appointments; ask what the consultation includes.