Medical condition

Hives (urticaria)

Raised skin welts or bumps that appear suddenly, are often very itchy, and may change location or join together.

Medical taxonomy

Diseases of the skin

Taxonomy is used to organize content and does not represent a diagnosis.

Common causes

An allergic or immune response that releases substances causing superficial skin swelling; sometimes with no clear cause.

Risk factors

Allergy to a food, medication, or insect sting, or triggers such as heat, cold, or stress.

Red flags — seek urgent care

Swelling of the face, lips, throat, or tongue, difficulty breathing or swallowing, or dizziness — these can be signs of a severe allergic reaction (anaphylaxis).

Suggested next step

Avoid the likely trigger; antihistamines may ease symptoms. Seek review if hives last more than a few days or recur, and seek emergency care immediately with any red-flag sign.