The medical term for hives is urticaria, also called wheals (bumps). Swollen, small, pale red bumps or larger patches suddenly appear on the skin. Severe itching usually follows. Each bump tends to go away in 24 hours without leaving marks, but then others appear. They can be very small to large. Scratching can cause the affected skin area to get larger, leading to big, fiery red patches. Hives usually don’t last long. When they last more than 6 weeks, they’re called chronic; when they last less than 6 weeks, they’re called acute.
Hives can be allergic or nonallergic, but often the cause remains unknown. Allergic hives, the least common, are triggered by an overreaction of the immune system to certain things, most commonly foods (nuts, shellfish), insect stings and bites, and drugs (e.g., penicillin).
Causes of nonallergic hives include cold (after exposure to cold weather) and heat (after exercise, hot shower, or stress).
Symptoms include itching, or less often burning or stinging; raised, often red, swellings; and separate swellings that usually go away in 24 hours, but new ones often appear as the old ones disappear.
The health care provider will ask about symptoms: when they appeared, how long they lasted, what things may have triggered them. If the health care provider thinks that an allergy is the cause, seeing a specialist in allergies may be suggested. A diary of foods eaten, drugs taken, illnesses, work and home life, and when symptoms appear should be kept.
No specific tests are used for these conditions, so the choice of tests depends on answers to questions about symptoms and a full physical examination. Sometimes, blood and urine tests and skin testing may be done.
Antihistamines (like those taken for hay fever) are the most common treatment. In complicated or severe cases, drugs called corticosteroids (prednisone) may be prescribed for a short time.
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