Urticaria

A urticarial reaction can be caused by a wide range of triggers.

• Food, drugs and other foreign substances can result in the formation of weals both via allergic and allergic-like (pseudo-allergic) reactions.
• Insect bites, plants, painkillers (e.g. acetyl salicylic acid), infections (often virus infections of the upper airways, but also fungal infections, etc.), water, exertion and stress and depressions can also be considered as triggers.
• Pressure, cold, heat and light are typical triggers of physical urticaria.
• Frequently, the actual cause is unclear. Doctors then talk of an idiopathic urticaria.

Almost all symptoms (weals, itching) that develop within the scope of urticaria are to be attributed to the distribution of histamine and other messenger substances of the body's own defence (immune system). The distribution of histamine is a normal reaction by the immune system to an 'invader'. It is conveyed by so-called mast cells that react quickly to a whole diversity of stimuli by releasing histamine. Histamine leads to a widening of blood vessels and activates nerves located in the skin. As a result of the widening of the vessels, blood serum enters the surrounding area which leads to typical weals. Redness and itching are caused by histamine.