Unpleasant symptom of a number of skin disorders, arising because a large number of nerves are slightly irritated simultaneously. Scratching irritates them more, and the itch disappears. Itching is particularly common in constitutional eczema, but can also occur in contact eczema. A birthmark that itches, bleeds or increases in size can be a sign of melanoma (a malignant skin tumour), which requires treatment as soon as possible. Fungus infections of the skin, particularly between the toes (athlete’s foot) and fingers, cause pruritis, and these places are difficult to scratch. Bites or stings from insects, gnats or fleas are often itchy, and persistent itching can be a sign of scabies, infestation with a mite which lays eggs in the horn layer of the skin. As well as these skin disorders, a number of other diseases can cause pruritis; among them are diabetes mellitus, jaundice and Hodgkin’s disease. Itching itself is without physical consequence; problems are caused when the patient cannot stop scratching and injures his skin to the extent that infection can set in (impetigo). Treatment is directed at the cause. If the cause cannot be found, ointments containing camphor or menthol sometimes afford relief; the same is true of ointments with a slight anaesthtic effect. Ointments containing large doses of corticosteroids should be prescribed only as a last resort.