Acute urticaria can be triggered by allergens, irritants, infections, medicines or physical factors like heat or exercise.
High levels of histamine and other chemical messengers released in the skin cause the blood vessels in the affected area to open up and leak. This extra fluid causes itching, swelling and a red/pink colour.
Chronic urticaria, however, is linked to other conditions, such as autoimmune problems. With chronic urticaria, the immune system is mistakenly attacking healthy tissue.
Sometimes no obvious cause can be located, however, there are certain triggers that make symptoms worse that include:
- Drinking alcohol or caffeine
- Emotional stress
- Increasing body temperature
The condition consists of spots or patches of raised red or white skin, which usually clear away in a few hours and are then replaced by fresh patches. It typically occurs with swelling in other areas of the body (usually the hands and feet) and will be itchy, painful or cause a burning sensation.