What are hives?

Called urticaria, hives are an allergic reaction. It's rarely clear what triggers hives. They can be stress-related. These pink, itchy swellings are caused by the release of histamine and other chemicals in the skin. Eggs, chocolate, seafood, nuts, milk and medications are occasional triggers of hives for some people, as are exposure to cold temperatures or infections. Individual hive lesions generally fade in 24 hours or less. When hives develop in the throat, breathing can become difficult and may be life threatening; in this case, immediate treatment is required.
Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
Hives are the raised, itchy red patches that appear when your body releases a chemical known as histamine in response to an allergen. Foods like shellfish, fish, peanuts, tree nuts, eggs, and milk are frequent histamine-triggers, as are medications like penicillin, aspirin, ibuprofen, naproxen, and blood pressure medications. Other substances that can lead to hives include pollen, animal dander, latex, and insect stings. Your body mistakes these common substances as threats and produces allergy antibodies to combat them, releasing the histamine that causes inflammation and hives.

Fortunately, there’s an easy fix for hives. Acute hives are those caused by stress or allergies, and can be treated with an oral antihistamine. Topical antihistamine won’t do a lot but may relieve some itching. If after six weeks an oral histamine hasn’t eliminated your hives, you should see your doctor. And if you experience trouble breathing at any point, see a doctor immediately.
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Lawrence T. Chiaramonte, MD
Allergy & Immunology
Hives is the common name for urticaria, a distressing disorder that affects an estimated 20 percent of the population at one time or another. It is characterized by itchy, red, blanching on the surface of the skin. Urticarial lesions come and go and do not persist in a given location for more than 24 hours. The most common form of hives is known as "wheal-and-flare," which may be a single red blotch or a cluster of them, and is triggered by the presence of an allergen in the area followed by the release of histamine when mast cells degranulate. Most cases of urticaria are acute, lasting from a few hours to less than six weeks. In most acute cases, the trigger is obvious -- a person eats strawberries or shrimp, for example, then develops urticaria within a short time.
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Hives are red, itchy, welts on the skin that are typically caused by an allergic reaction to food or medication. They typically do not cause any lasting effects, though they can be irritating.

Hives are itchy, red bumps on the skin. They can be different sizes, and they may come and go over time. Hives are an allergic reaction to something your body considers to be an irritant.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.