What dandruff is
Dandruff is the shedding of small white or yellowish flakes of skin from the scalp, often with itching. The flakes fall on the shoulders and are more noticeable on dark clothes. Dandruff is very common, especially from the teenage years to middle age, and it is not caused by poor hygiene, although infrequent hair washing can make flakes more visible.
Dandruff is a mild form of a condition called seborrhoeic dermatitis. In some people the same condition also causes redness and greasy scaling on the eyebrows, the sides of the nose, behind the ears and on the chest. In babies, a similar thick, yellow scale on the scalp is called cradle cap and is usually harmless.
What causes it
A yeast called Malassezia lives on everyone's scalp. In some people it overgrows or their skin reacts to it, especially where oil production is high. This speeds up the turnover of skin cells, which clump together and form flakes. It is not an infection that spreads from person to person.
Dandruff usually comes and goes over the years. It tends to get worse in the winter months and during stressful periods, and often improves in summer or with regular washing. It is a long-term tendency rather than a one-time problem, so most people need to keep using a medicated shampoo now and then to stop it returning.
- Oily scalp and hormone changes
- Leaving heavy hair oil on the scalp for long periods
- Sweating and humid weather, or dry winter air
- Stress and lack of sleep
- Infrequent washing, allowing oil and flakes to build up
- Conditions such as Parkinson's disease or low immunity, which can make it severe
Is it dandruff or something else?
Several scalp conditions look like dandruff. Psoriasis causes thick, silvery scales in well-defined patches that may extend beyond the hairline. Fungal infection of the scalp (tinea capitis), which is common in children, causes round patches of hair loss with scaling and broken hairs. Head lice cause intense itching, and small white eggs stick firmly to hair shafts.
Contact dermatitis from hair dye, henna mixtures or new hair products can also cause itching, redness and flaking, often starting within a day or two of use. If the scalp is red, sore, weeping or losing hair in patches, see a doctor rather than treating it as simple dandruff with shop products.
Treatment with medicated shampoos
Medicated anti-dandruff shampoos are the main treatment. Look for active ingredients such as ketoconazole, selenium sulphide, zinc pyrithione, coal tar or salicylic acid. Massage the shampoo into the scalp, not just the hair, and leave it on for a few minutes before rinsing, as the label advises. Use it more often at first, then less often to keep dandruff away.
If one shampoo stops working after some months, switching to one with a different active ingredient often helps. Using two types in rotation also works for some people. For stubborn cases, a doctor may prescribe a mild steroid lotion for a short time to calm itching and redness, or an antifungal lotion for the scalp.
Scalp care habits
Simple daily habits make treatment work better and help keep flakes away once they are under control. Children, pregnant women and people with sensitive skin should ask a pharmacist or doctor before using strong medicated shampoos, such as coal tar products, which can irritate delicate skin.
- Wash your hair regularly, more often if your scalp is oily
- If you oil your hair, apply it for a short time and wash it off well
- Rinse out shampoo and conditioner thoroughly
- Avoid scratching the scalp with nails or sharp combs
- Manage stress and get enough sleep
- Do not share combs or towels if a fungal infection is suspected
When to see a doctor for dandruff
See a doctor if dandruff does not improve after four to six weeks of regular medicated shampoo, if the scalp is very red, painful or oozing, or if you notice patches of hair loss. Children with scaly scalp patches should be checked for fungal infection, which needs tablets on a doctor's prescription. A doctor or pharmacist can recommend the right shampoo and routine for your scalp.
Medicines doctors commonly use
Only your doctor can decide which medicine, dose and combination is right for you.
- Ketoconazole shampooReduces the yeast on the scalp that drives dandruff.Follow the label or your pharmacist's advice; keep it away from the eyes.
- Selenium sulphide or zinc pyrithione shampooSlows skin cell turnover and reduces yeast and flaking.Follow the label; selenium sulphide can discolour chemically treated or grey hair.
- Coal tar or salicylic acid shampooLoosens and removes thick scales and slows flaking.Ask a pharmacist before use in children or pregnancy; coal tar can irritate skin.
- Mild topical steroid scalp lotionsCalm severe itching and redness for a short period.Only on a doctor's prescription and for short-term use.
See a doctor urgently if
- See a doctor soon if you notice patches of hair loss with scaling, especially in a child.
- See a doctor soon if the scalp is painful, swollen, oozing pus or crusted.
- See a doctor soon if thick silvery scales spread beyond the hairline or appear on elbows and knees.
- See a doctor if the flaking spreads to the face, ears or chest with redness.
- See a doctor if symptoms continue after six weeks of regular medicated shampoo.
Tests that may help
This article is general health information, not medical advice. Do not start, stop or combine medicines on your own — always follow your doctor's prescription and ask your pharmacist if unsure.