Urticaria (hives) is an itchy rash or skin eruption, which may occur anywhere on the body. It is usually temporary, disappearing within 24 to 48 hours. The rash has red weals (hard, raised patches of skin) and is usually itchy. Individual weals may come and go quite quickly — over hours.
Urticaria is sometimes due to an allergic reaction to drugs, food or preservatives, but may also be due to fever, heat, exercise or physical pressure. Often the cause is not identified. Urticaria may also be caused by infections, such as hepatitis or even a cold.
Dermographism is a physical urticaria where firm stroking of the skin produces a red line which swells and becomes surrounded by a red flush of the nearby skin. There can be a weal down the line of the stroke. Dermographism literally means ‘writing on the skin’.
If you know what causes the urticaria, avoid it. If aspirin precipitates urticaria it is important to see a doctor before using any other non-steroidal anti-inflammatory (NSAID) medicine.
A tepid shower may be soothing. However, heat may make the itch worse. You should also avoid tight clothing as the pressure may worsen the weals and the itch. Antihistamine medication is often helpful. If the urticaria does not respond to an antihistamine, see your doctor.
You should seek medical advice if:
Last Reviewed: 19 April 2009