Hives (urticaria)

For a lay person:

Hives, or urticaria, are raised, itchy welts on the skin that come and go, often within a day. They can be triggered by allergies, infections, medicines, heat, cold or pressure, but often no cause is found. Hives lasting more than six weeks are called chronic urticaria.

For a trained medical person:

Mast cell degranulation releases histamine and other mediators, causing wheals with or without angio-oedema; acute urticaria is often triggered by infection, drugs or food, while chronic spontaneous urticaria is frequently autoimmune. Diagnosis is clinical, with limited tests guided by history and challenge testing for inducible types. Treatment is trigger avoidance and second-generation antihistamines up to higher licensed doses, then omalizumab or ciclosporin for refractory chronic urticaria.

In Chinese medicine:

Liu and Tseng's textbook differentiates this condition into these patterns: Wind-Heat; Wind-Cold; Wind-Toxin Stasis and Dampness. Treatment follows the pattern a patient presents with, not the Western diagnosis alone.

When to get help: Call emergency services for swelling of the tongue or throat, difficulty breathing or swallowing, dizziness or collapse, as these may be anaphylaxis. Herbs can themselves cause allergic reactions, so stop any new herb that coincides with hives.