What are hives?
Hives are raised red bumps (welts) or splotches on the skin. They’re a type of swelling on the surface of your skin and happen when your body has an allergic reaction. Allergic reactions happen when your immune system comes in contact with an allergen. Allergens are proteins that are harmless to many people but cause an allergic reaction in sensitive people.
Hives are often very itchy, but you might also feel burning or stinging. They can be as small as a fingertip or as big as a dinner plate. The medical name for hives is urticaria.
Sometimes, the welts from hives join together to form larger areas called plaques. Hives tend to fade within 24 hours, although they may be noticeable for several days or longer.
Types of hives
Acute urticaria refers to hives that don’t last very long (less than six weeks). Chronic urticaria refers to hives that happen at least twice a week for more than six weeks.
Chronic, spontaneous urticaria is the name for chronic hives that don’t have an obvious cause. An older name for this condition is chronic idiopathic urticaria.
There’s also a condition called physical urticaria, or inducible urticaria. These hives might pop up when you’re in the cold, heat or sun. Some people react to vibrations or pressure, exercising or sweating. Physical hives usually appear within an hour after exposure. This type of hives can also be chronic.
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What’s the difference between hives and a rash?
A rash is a skin condition that involves something out of the ordinary, like spots, swelling, itchiness or redness. Hives is an example of a rash, but not all rashes are hives.
Who is affected by hives?
Anyone can get hives. If you’re someone who reacts to many types of allergens, you may get hives frequently. Other people who don’t react to allergens may get hives once or a few times in their lives.
There seems to be a relationship between acute hives and conditions like asthma, allergic rhinitis and atopic dermatitis, especially in children. You might also be affected by hives during periods of extreme stress.
How common are hives?
Around 20% of the population will get hives at least one time. About 1% to 3% of the population has chronic hives.
