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What's causing these mysterious hives?

AAFA's "Ask the Allergist" is a free service provided by the Asthma and Allergy Foundation of America (AAFA). Our allergist will answer your questions about asthma and allergies. We provide only general advice about managing asthma or allergies, medicines and treatments. "Ask the Allergist" does not answer questions about specific consumer products. This information is not a substitute for medical advice from your physician. Always talk with your doctor before changing your asthma or allergy management plan.

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I don't know what I am allergic to, but I keep getting hives. They go away but come back when I am sleeping.

If your hives have been occurring for over 6 weeks, the hives are not likely caused by an allergy. When hives occur for more than 6 weeks, we typically call it β€œchronic urticaria”.

When we can't find the cause of the hives, it's called β€œchronic spontaneous urticaria” or "CsU". This is the most common cause of hives when they occur over   6 weeks. People with CsU do not have allergies. Research suggests that the hives are caused by the spontaneous release of histamine from skin allergy cells. This is not caused by an allergic trigger. It may be due to the accidental development of an antibody. This antibody binds to allergy cells and breaks them open. This causes the spontaneous release of histamine which causes hives and itching. This often resolves over time but can last months to years.

Treatment includes the use of non-drowsy antihistamines which you can buy over the counter. Current guidelines for the treatment of CsU support using more than the recommended dose.

I would suggest a consultation with a board-certified allergist. Board-certified allergists are very familiar with how to treat CsU and could help you better manage your symptoms.

Hives (Urticaria)
Answered by

Douglas T. Johnston D.O. FAAAAI, FACAAI

Reviewed and Answered

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