[Urticaria].

Urticaria may affect as many as 25% of all people at some time during their lives. The hallmark of urticaria are transitory and completely reversible wheals (intracutaneous oedema). There are multiple causes of urticaria. It has various clinical expressions. Corresponding to the time course it is possible to differentiate between acute, acute relapsing and chronic urticaria. Acute and acute relapsing urticaria is often caused by an allergy or "pseudoallergy". Causal factors of chronic urticaria are usually elusive and therefore only a symptomatic treatment is possible. H1 antihistamines with a low potential for sedation are the most important first-line treatment.