Urticaria (hives) is a common eruption which can suddenly appear affecting any part of the skin. Small raised areas called wheals appear which are itchy and may look like blisters. They usually disappear within 24 hours but recurrent crops can appear over several weeks or months.
In about half of cases the triggering factor can be identified, it may be a viral infection, type of medication (both prescribed and bought over the counter), or a particular food such as nuts, strawberries, citrus fruit, egg, food additives, spices, chocolate, or shellfish. Investigations may be needed to try and establish the cause of the urticaria. In some people a cause is never found and the urticaria fades away with time. Treatment of severe urticaria is with specialist regimes of antihistamine and other medication.