What is dandruff?
Dandruff is a common skin condition that causes flakes of dead skin to appear in the hair.
Dandruff can also make the scalp feel itchy.
The condition is not contagious and does not usually pose a threat to health, but can be unpleasant and embarrassing.
Dandruff can range from mild to severe.
Read more about the symptoms of dandruff.
The main treatment for dandruff is anti-dandruff shampoo. There are a number of different types available over the counter from most pharmacists and supermarkets.
The different types can work in different ways, 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, you should see your doctor. 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.
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.
In cases of dandruff this process speeds up and excessive amounts of dead skin cells are released by the scalp.
It's not always clear why this happens, but possible causes include seborrhoeic dermatitis, a common skin condition that causes oily skin.
While not directly responsible, certain things can make your dandruff worse, such as:
- frequent use of hairspray, hair gel and mousse
- emotional stress
Read more about the causes of dandruff.
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.
The main symptom of dandruff is white or grey dry flakes of skin on your scalp and in your hair. The flakes are often noticeable if they fall from your scalp on to your shoulders. Your scalp may also feel itchy and dry.
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.
Babies can develop yellow, greasy scaly patches on their scalp. This is known as cradle cap.
Cradle cap appears most often in babies in the first two months and tends to last only a few weeks or months. It usually clears up by the age of two, although in rare cases children can have cradle cap a lot longer.
Read more about treating cradle cap.
When to seek medical advice
You should contact your doctor if your symptoms show no signs of improvement after using anti-dandruff shampoo for two weeks. You may require stronger prescription treatment.
Also see your doctor if you think you have developed symptoms of seborrhoeic dermatitis. Again this condition may require prescription medication to control.
Causes of dandruff
Dandruff is caused when the natural cycle of skin renewal is speeded up.
This leads to patches of dead skin forming on the surface of the scalp, which come away into the hair, resulting in the flakes associated with dandruff.
What causes the skin renewal cycle to speed up is not always clear. Possible factors may include:
- Seborrhoeic dermatitis – a common yet poorly understood condition that causes oily skin; people with seborrhoeic dermatitis can also experience flaking on other parts of the body such as the eyebrows, the side of the nose and anywhere where skin folds together, such as the armpits.
- Malassezia – a type of fungus that normally lives harmlessly on skin but, if it grows out of control, can accelerate production of new skin.
These are thought to be interlinked. The presence of the fungus on skin may provoke an abnormal response from the immune system (the body’s defence against infection), which can then cause skin to become oily.
In turn, oiliness of the skin may encourage further growth of the fungus, which then triggers symptoms of dandruff.
Other possible risk factors for dandruff include:
- emotional stress
- not washing your hair or, conversely, washing your hair too much – some people can irritate their scalp if they shampoo their hair too often
- using other hair products such as hairspray, hair gel and hair mousse
- other skin conditions such as psoriasis or eczema – two common skin conditions that can cause skin to become dry, red and flaky
- having a weakened immune system, which can be the result of a condition such as HIV or as a side effect of a treatment such as chemotherapy
For reasons that are unclear, people with Parkinson’s disease often develop both dandruff and seborrhoeic dermatitis.
Dandruff does not usually need to be formally diagnosed because its symptoms are obvious. The characteristic dry, white flakes on your scalp or in your hair are typical of the condition.
See your doctor if you think you have seborrhoeic dermatitis. They can diagnose the condition by looking at the red rash on your skin. Tests are not usually required.
Ruling out other skin conditions
To confirm a diagnosis of seborrhoeic dermatitis, your doctor will examine the redness and colour of the scaling on your scalp.
This will enable your doctor to rule out a different skin condition called psoriasis, which causes red, flaky, crusty patches of skin and silvery scales and has similar symptoms to seborrhoeic dermatitis.
If your doctor 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.
Treatment for dandruff
If the symptoms of your dandruff are mild then it may be possible to relieve symptoms using self care techniques.
- Washing your hair daily with a mild shampoo until the dandruff clears; shampoos containing tea tree oil can be particularly effective.
- Try not to scratch your scalp when using shampoo; instead, gently massage your scalp without scratching as this will not damage your scalp or your hair.
- Avoid using hair products such as hairspray and gel until the dandruff clears.
Spending time outdoors in the sun can help reduce dandruff. However, ensure you protect yourself with sunscreen with the appropriate skin protection factor (SPF) for your skin type.
If your dandruff is severe you will probably require treatment with an anti-dandruff shampoo. These are available over the counter from most supermarkets and pharmacists.
Some of the most widely used anti-dandruff shampoos include:
- Zinc pyrithione – which works by killing the malassezia fungi thought partially responsible for dandruff.
- Salicylic acid – which helps soften and shed dead skin cells on your scalp (some people experience dryness of their scalp after using salicylic acid; using a conditioner after the shampoo can often help).
- Selenium sulfide – this works by both slowing production of skin cells while also killing the fungi.
- Ketoconazole shampoo – which has a powerful antifungal effect.
- Coal tar shampoo – this again can help slow production of dead skin cells.
Not every shampoo is suitable for everyone. For example, selenium sulfide may not be recommended for people with blonde or chemically treated hair as it can discolour the hair.
And as a precaution the use of certain types of anti-dandruff shampoo may not be recommended if pregnant or breastfeeding. So it is always important to carefully read the instructions that come with the shampoo.
If in doubt ask your pharmacist or doctor for advice.
Applying the shampoo
It is normally recommended you apply whatever anti-dandruff shampoo you decide to use daily or every other day. (An exception is if you are using ketoconazole shampoo which usually only needs to be applied twice a week.)
Once your symptoms improve, you may only need to use the shampoo two or three times a week.
Gently massage the shampoo into your hair and then leave for at least five minutes to allow the ingredients time to take effect.
If one type of shampoo does not prove effective or starts to lose its effectiveness then try another type.
If you do not experience an improvement in symptoms after a few weeks of using a shampoo, contact your doctor for advice.
If you also develop symptoms of seborrhoeic dermatitis, where you have scaling of skin in other parts of the body, your doctor may recommend you use a cream or lotion containing ketoconazole.
If you have a flare-up of symptoms you may be prescribed a short course of a steroid cream or lotion (topical corticosteroids). The long-term use of topical corticosteroids is not usually recommended, as it can lead to side effects such as thinning of the skin.