What causes hives?
Mast cells in the skin release histamine, making small blood vessels leak and swell. Acute hives are often triggered by foods (shellfish, nuts), medications (NSAIDs, antibiotics) or viral infections. Chronic hives, lasting six weeks or more, usually have no identifiable cause; some are set off by pressure, cold or heat (Zuberbier et al., 2022).
How are hives treated?
Non-drowsy antihistamines like cetirizine or fexofenadine are first-line; doctors may raise the dose up to four times or add omalizumab for stubborn cases. Swelling of the lips or tongue, trouble breathing or dizziness may signal anaphylaxis—use epinephrine if prescribed and call 911. Long-lasting itchy patches may be eczema instead.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Do I need allergy testing for chronic hives?
- Usually not—chronic hives are rarely caused by food allergy, so testing is guided by history.
- Are hives contagious?
- No.
Sources reviewed: 2026-10-25
References
- Zuberbier, T., et al. (2022). The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for urticaria. Allergy, 77(3), 734–766.