Seborrhoeic dermatitis of the scalp

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 it is

Seborrhoeic dermatitis (sometimes called seborrhoeic eczema) is an inflamed, flaky, itchy rash that affects oily areas of skin — the scalp, eyebrows, sides of the nose, ears, chest and back. On the scalp it ranges from simple dandruff to red skin with thicker, yellowish or greasy scale. In babies the same tendency is called cradle cap, which usually clears on its own.

It's linked to Malassezia, a yeast that lives on everyone's skin but is found in larger amounts where seborrhoeic dermatitis is active. It isn't an infection you can catch, and it isn't caused by poor hygiene.

Why it comes and goes

Dermatologists describe it as a long-term condition that flares and settles over many years. BAD lists tiredness, stress and cold, dry weather as common triggers. There's no cure, but treatment usually controls it well — and it may flare again when treatment stops, which is why maintenance matters.

What helps

Antifungal shampoo first

The mainstay is a medicated shampoo that reduces the yeast:

• Ketoconazole 2% is the usual first choice. The NHS suggests using it twice a week for 2 to 4 weeks until symptoms clear, then once every 1 to 2 weeks to stop them coming back. Leave it on the scalp for a few minutes (3 to 5 minutes, NHS) before rinsing.
• Alternatives named by BAD and NICE include selenium sulfide, zinc pyrithione, coal tar and salicylic acid shampoos.

Thick scale: soften it first

If there are thick, stuck-on scales, a descaling product (often containing salicylic acid and coconut oil) applied a few hours before washing helps lift them so the shampoo can reach the skin. Follow the product instructions.

Flare-ups: a short steroid course

For a very inflamed or itchy flare, a GP may prescribe a steroid scalp lotion or mousse for a short time. These are prescription medicines and aren't meant for continuous long-term use.

Everyday care

• Keep using the medicated shampoo once or twice a week when your scalp is clear.
• Try gentle, unperfumed products on the face and body if those areas are affected.
• Stress and lack of sleep can trigger flares — worth knowing even if they're hard to avoid.