Symptoms and Complications
Hives are areas of red itchy skin. There may be one big rash or several smaller ones. They're often large and slightly raised. The edge of the rash is often the most inflamed part. There may be pain or burning instead of itching.
Acute hives usually last no more than 24 hours, but some cases can last up to 6 weeks. Chronic hives last for more than 6 weeks. Most, however, last about a week.
Occasionally the rash is more than skin-deep. If histamine and other inflammatory agents are released into the layers just under the skin, the swelling is more severe and itching is likely to be replaced by pain. This condition is called angioedema.
Angioedema can cause alarming swelling in the mucus membrane of the lips, mouth, gut, genitals, or throat. The swelling usually goes down within a day, but very rarely it interferes with breathing and requires emergency treatment. If you experience hives that are associated with dizziness, difficulty breathing or angioedema, get immediate medical attention.