Urticaria.
Urticaria is a very common skin disease which was already described in the ancient world. Questions still remain about its pathogenesis and management remain open. Compared to other common skin diseases, the published evidence is rather low. The clinical symptoms with pruritic transient wheals and/or angioedema are caused by mediators (particularly histamine) released by activated mast cells and basophils. The mechanism of target cell activation has not been clarified in detail for most urticaria subtypes. Different urticaria subtypes should be distinguished. Spontaneous forms are more common than inducible forms. Chronic urticaria and urticaria in certain age groups (children, pregnancy) can be difficult to manage. Therefore, international consensus resulting in the regular update of urticaria guidelines can be very helpful. Currently, these updated guidelines include a three-step treatment algorithm for chronic spontaneous urticaria. Only the first step of this algorithm, second generation H1-antihistamine in standard dose, utilized approved drugs. However after omalizumab was established as a third line choice in the guideline algorithm, it has approved in many countries for chronic spontaneous urticaria without response to H1-antihistamines. The exact mechanism of action of omalizumab in urticaria has not been fully elucidated. Unrevealing this mechanism might result in a deeper understanding of urticaria pathogenesis and the development of further therapeutic strategies.