Dandruff is a common skin condition that causes dry white or grey flakes of dead skin to appear in the scalp or hair.

The flakes are often noticeable if they fall from your scalp on to your shoulders. Your scalp may also feel dry and itchy.

It's not contagious and doesn't usually pose a threat to health, but can be unpleasant and embarrassing.

Dandruff can range from mild to severe.

What causes dandruff?

The body continually sheds dead skin cells as new cells are formed. In most cases, this is a gradual process that goes unnoticed.

However, this process can speed up, producing excessive amounts of dead skin cells, which causes dandruff.

It's not always clear why this happens, but possible causes include seborrhoeic dermatitis (see below), a common skin condition that causes oily skin.

While not directly responsible, certain things can make your dandruff worse, such as:

• overuse of hair products
• emotional stress
• washing your hair too much or too little

Read more about the causes of dandruff.

Seborrhoeic dermatitis

If your dandruff is associated with the skin condition seborrhoeic dermatitis, you may also experience additional symptoms.

These can include scaling and itching of the skin. Areas of the body most commonly affected include:

• the scalp
• the face
• in and around the ears
• the front of the chest and between the shoulder blades
• areas where the skin folds together, such as your armpits, groin and inner thighs

The scaling can range from some mild pink patching to widespread thick crusts of skin.

In some cases the scales can become infected, which can lead to the patches becoming red, painful and discharging pus and fluid.

Severe cases of patching on your scalp can result in some degree of hair loss. However, if there is no scarring, the hair should regrow.

Treating dandruff

The main treatment is anti-dandruff shampoo. There are a number of different types available over the counter from most pharmacists and supermarkets.

These work in different ways, depending on the type, so if one type isn't effective you may want to try another one.

If treatment fails to clear your flaky scalp after a few weeks, or your scalp is particularly itchy, see your GP. You may need stronger prescription shampoo or a short course of a steroid lotion.

Dandruff usually responds well to treatment, but it's common for it to reoccur. Some people find they are free from symptoms for a while before having a "flare-up", where symptoms are particularly bad.

In some cases, you may need to use anti-dandruff shampoo on a regular or semi-regular basis to prevent dandruff returning.

Read more about the treatment of dandruff.

When to see your GP

See your GP if your symptoms show no signs of improvement after using anti-dandruff shampoo for two weeks. You may require stronger prescription treatment.

Your GP can examine your scalp to rule out skin conditions such as seborrhoeic dermatitis or psoriasis, which may also require prescription treatment.

If your GP thinks a fungal infection may be present in your scalp (for example, scalp ringworm), a skin sample may be taken and sent to a laboratory for testing.

Who is affected

Dandruff is a common condition. It is estimated that half of all people will be affected by dandruff at some point in their lives.

Dandruff often occurs after puberty and is most common in people in their early 20s, continuing into middle age.

It has been reported that dandruff is more common in men than women. It is thought to affect all ethnic groups equally.