Seborrhoeic dermatitis

Seborrhoeic dermatitis tends to affect areas with more oil glands, such as the scalp, eyebrows, the sides of the nose and behind the ears. It can cause greasy or yellowish scales, redness and itching. Dandruff is generally thought of as a milder form of the same process.

It is linked with an overreaction of the skin to a yeast called Malassezia that lives on everyone's skin. It is not caused by poor hygiene and is not contagious. It often comes and goes, and may flare with stress, cold weather or illness.

Medicated shampoos from a pharmacy help many people. If it does not improve, is very inflamed or spreads, see your GP, who can suggest stronger treatment or check whether another condition, such as scalp psoriasis, is involved.