Seborrhoeic dermatitis causes red, oily, scaly, itchy patches on the skin. It commonly affects the scalp, face, ears and chest. In babies, it is called “cradle cap” and usually goes away by itself in a few weeks or months. The cause is unknown but is thought to be an overgrowth in yeast on the skin causing an inflammatory reaction. Symptoms in adults can get worse when you are tired, stressed, generally unwell and in very cold or very warm weather. It is usually treated with medicated shampoos and corticosteroid gels or lotions.