Hives happen when the body releases histamine, causing fluid to leak from small blood vessels under the skin. Triggers include allergic reactions to foods, medicines or insect bites, as well as infections, heat, cold, stress and exercise. Often no specific cause is found.

How long do hives last?

Most cases (acute urticaria) clear up within a few hours to a couple of days. If hives keep appearing for more than 6 weeks, it is called chronic urticaria and should be assessed by a GP.

How do I get rid of hives?

Antihistamines from a pharmacy usually relieve the itching and help the rash settle. Avoiding any known trigger, keeping cool and avoiding tight clothing can also help.

When are hives an emergency?

Hives themselves are usually not dangerous, but if they come with swelling of the face, mouth or throat, breathing difficulty or feeling faint, this may be a severe allergic reaction and needs an emergency 999 call.

Hives (urticaria) | HealthAnswers

Quick answer

What is hives (urticaria)?

Hives, also called urticaria, are a raised, itchy rash that can appear anywhere on the body. They are often caused by an allergic reaction or triggered by heat, stress or infection. Most cases settle within a day or two, and antihistamines from a pharmacy usually ease the itching.

What are hives?

Hives, known medically as urticaria, are a raised, itchy rash. The raised areas (weals) can be small spots or large blotches, are often pink or red on lighter skin, and may join together. Hives can appear suddenly anywhere on the body and often move around, fading in one place and appearing in another.

Symptoms

The main features are:

raised bumps or patches that are very itchy
areas that may look pink or red, or skin-coloured on darker skin
a rash that can change shape and location over hours
sometimes mild swelling under the skin

What causes them

Hives occur when the body releases a chemical called histamine, which makes small blood vessels leak fluid into the skin. This can be triggered by allergic reactions — to foods, medicines or insect stings — or by things like infections, heat, cold, stress and exercise. In many cases no clear cause is found.

Treatment

Most short-lived hives do not need specific treatment and settle by themselves. Antihistamines from a pharmacy usually ease the itching and help the rash clear. Keeping cool, wearing loose clothing and avoiding any known trigger can also help.

When to seek help

See a GP if hives keep returning or last more than six weeks, as long-lasting (chronic) hives may need further treatment. Most importantly, treat hives with swelling of the face or throat, breathing difficulty or faintness as a medical emergency.

Common questions

What causes hives?: Hives happen when the body releases histamine, causing fluid to leak from small blood vessels under the skin. Triggers include allergic reactions to foods, medicines or insect bites, as well as infections, heat, cold, stress and exercise. Often no specific cause is found.
How long do hives last?: Most cases (acute urticaria) clear up within a few hours to a couple of days. If hives keep appearing for more than 6 weeks, it is called chronic urticaria and should be assessed by a GP.
How do I get rid of hives?: Antihistamines from a pharmacy usually relieve the itching and help the rash settle. Avoiding any known trigger, keeping cool and avoiding tight clothing can also help.
When are hives an emergency?: Hives themselves are usually not dangerous, but if they come with swelling of the face, mouth or throat, breathing difficulty or feeling faint, this may be a severe allergic reaction and needs an emergency 999 call.

Sources

NHS — Hives