Causes Acute hives may follow viral infections, foods, medicines, insect stings, heat, cold, pressure or exercise. In chronic urticaria lasting more than six weeks, a single external allergy is often not found.
Symptoms Individual welts usually fade within 24 hours, although new ones may appear. Deeper swelling of the lips, eyelids, hands or feet is called angioedema.
Treatment Non-sedating antihistamines are commonly used and may need regular dosing under medical guidance. Avoiding a confirmed trigger is helpful, but broad food restriction without evidence is not recommended. Persistent chronic hives may require specialist treatment.
Emergency warning signs Call emergency services immediately for difficulty breathing, throat tightness, faintness, wheezing or swelling of the tongue. Hives with bruising, pain, fever or marks lasting longer than 24 hours need medical assessment.
Frequently Asked Questions
Are hives always caused by food allergy?
No.
How long does one hive last?
Usually less than 24 hours.
What is chronic urticaria?
Hives occurring repeatedly for more than six weeks.
When is it an emergency?
When breathing, the throat or the tongue is affected.
This information is for education only and does not replace medical assessment or treatment by a qualified physician.