Dandruff: causes, shampoos that help and when to see a GP
Dandruff is common, harmless and not catching — and it isn't caused by poor hygiene. Here's what the NHS and dermatologists say helps, how to use anti-dandruff shampoo properly, and when flakes need a GP.
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Not medical advice. This guide is general information from the sources listed, not a diagnosis or a substitute for a pharmacist, GP or dermatologist. If you are worried, or symptoms are severe or not improving, get advice. Read our health information policy.
What dandruff is
Dandruff is white or greyish flakes of skin on the scalp and in the hair. The NHS describes it as a common skin condition that is "not harmful and you cannot catch it". Flakes tend to show up more on darker hair and on your shoulders, and the scalp may also feel dry or itchy.
Dermatologists see ordinary dandruff as the mildest form of seborrhoeic dermatitis — a long-term tendency to flaky, sometimes inflamed skin in oily areas such as the scalp. The British Association of Dermatologists (BAD) says dandruff affects almost half of all adults. If your scalp is also red, very itchy or greasy-scaly, read our seborrhoeic dermatitis guide.
What causes it
- A yeast that normally lives on skin. Both the NHS and BAD link dandruff to Malassezia, a yeast found on everyone's skin, which seems to trigger flaking in some people.
- Skin conditions such as eczema, psoriasis and seborrhoeic dermatitis.
- Things that make it worse: the NHS lists stress and cold weather.
It is not caused by poor hygiene — although, as the NHS points out, flakes can be more obvious if you don't wash your hair regularly.
Other conditions can look like dandruff, including scalp psoriasis, contact dermatitis (for example a reaction to hair dye or styling products) and, especially in children, scalp ringworm. If you're not sure, the NHS advice is to follow the self-care steps and see a GP if things haven't improved in about a month.
What helps: anti-dandruff shampoo
The NHS first step is an anti-dandruff shampoo from a pharmacy or supermarket containing one or more of:
- Ketoconazole — an antifungal medicine that targets the yeast.
- Coal tar — slows the build-up of skin cells; strong smell, can stain.
- Salicylic acid — loosens and lifts scale.
Dermatologists also mention selenium sulfide and zinc pyrithione shampoos. You may need to try more than one type to find one that works for you.
How to use it
- Wet your hair and massage the shampoo into the scalp, not just the lengths.
- Leave it on for the time on the pack — usually a few minutes (the NHS says 3 to 5 minutes for ketoconazole shampoo) — then rinse well.
- Use it as often as the pack says. For ketoconazole the NHS suggests twice a week for 2 to 4 weeks, then once every 1 to 2 weeks to stop dandruff coming back.
- Give it up to 4 weeks before deciding whether it works.
Between medicated washes you can use your usual shampoo and conditioner — apply conditioner to the lengths rather than the scalp.
Keeping it away
Dandruff tends to come and go. Many people keep it under control by carrying on with a medicated shampoo every week or two once the flakes have settled — the NHS says some people do this for months or years. Washing regularly enough to stop flakes and oil building up also helps.