Areas of swelling on the skin, often known as hives, that occur as the result of an allergic reaction

  • Sometimes runs in families
  • Age, gender, and lifestyle are not significant factors

Urticaria, also known as hives, is an intensely itchy rash that may affect the whole body or just a small area of skin. The rash consists of raised, red areas and, sometimes, white lumps. The inflamed areas usually vary in size and may merge to involve very large areas of skin. Urticaria typically lasts for only a few hours (acute urticaria), but in some cases it may persist for up to several months (chronic urticaria). Both the acute and chronic forms of urticaria may recur. Sometimes, urticaria occurs at the same time as the more serious condition called angioedema or is sometimes an early symptom of anaphylaxis.


This rash, known as urticaria, consists of white lumps and red, inflamed areas. It is usually caused by an allergic reaction.

What are the causes?

Urticaria can occur as a result of an allergic reaction to a particular food (see Food allergy). It may also be due to a drug allergy or an allergy to plants, or it may develop after an insect bite or sting. Urticaria may sometimes be associated with a viral infection or other disorder or a physical stimulus, such as pressure or a change in temperature. However, when it occurs for the first time, it is often difficult to identify the cause. The tendency to develop urticaria may sometimes run in families.

What might be done?

Acute urticaria usually disappears without any treatment within a few hours. The chronic form of the condition may take several weeks or months to clear up. Over-the-counter products such as calamine lotion and oral antihistamines may help to relieve itching.

If your symptoms persist or recur and the cause of the problem is not obvious, you should consult your doctor. He or she may arrange for a skin prick test to try to identify the substances to which you are allergic (allergens). When the substance causing your urticaria has been identified, you should avoid that substance in future.

Test: Skin Prick Test

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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