Hives — also known as urticaria (ur-tih-KAR-e-uh) — is a skin reaction that causes itchy welts, which range in size from small spots to large blotches. Hives can be triggered by many situations and substances, including exposure to certain foods or medications.
Angioedema can arise with hives or alone, causing swelling in the deeper layers of your skin, often around your face and lips. Hives and angioedema are common. Most times, they are harmless, clear up within in a day and don't leave any lasting marks, even without treatment.
Hives and angioedema are usually treated with antihistamine medication. Angioedema can be life-threatening if swelling causes your throat or tongue to block your airway.
The welts associated with hives can be:
- Itchy ranging from mild to intense
- Round, oval or worm-shaped
- As small as a pea or as large as a dinner plate
Most hives appear quickly and go away within 24 hours. Chronic hives can last for months or years.
Angioedema is a reaction similar to hives that affects deeper layers of your skin. It can appear with hives or alone. Signs and symptoms include:
- Welts that form in minutes to hours
- Swelling and redness, especially around the eyes, cheeks or lips
- Pain or warmth in the affected areas
When to see a doctor
You can usually treat mild cases of hives or angioedema at home. See your doctor if your symptoms continue for more than a few days.
If you think your hives or angioedema were caused by a known allergy to food or a medication, your symptoms may be an early sign of an anaphylactic reaction. Seek emergency care if you feel your tongue, lips, mouth or throat is swelling or if you're having trouble breathing.
Hives and angioedema can be caused by:
- Foods. Many foods can trigger reactions in people with sensitivities. Shellfish, fish, peanuts, tree nuts, soy, wheat, eggs and milk are frequent offenders.
- Medications. Many medications may cause hives or angioedema. Common culprits include penicillin, aspirin, ibuprofen (Advil, Motrin IB, others), naproxen sodium (Aleve) and blood pressure medications.
- Airborne allergens. Pollen and other allergens that you breathe in can trigger hives, sometimes accompanied by upper and lower respiratory tract symptoms.
- Environmental factors. Examples include sunlight, vibration such as from using a lawn mower, hot showers or baths, pressure on the skin such as from tight clothing or scratching, emotional stress, insect bites and exercise.
- Medical treatments or underlying conditions. Hives and angioedema also occasionally occur in response to blood transfusions and infections with bacteria or viruses such as hepatitis and HIV.
Oftentimes, no specific cause can be identified, especially in the case of chronic hives.
Hives and angioedema are common. You may be at increased risk of hives and angioedema if you:
- Have had hives or angioedema before
- Have had other allergic reactions
- Have a family history of hives, angioedema or hereditary angioedema
Severe angioedema can be life-threatening if swelling causes your throat or tongue to block your airway.
To lower your likelihood of experiencing hives or angioedema, take the following precautions:
- Avoid known triggers. If you know what triggered your hives, try to avoid that substance.
- Bathe and change your clothes. If pollen or animal contact has triggered your hives in the past, take a bath or shower and change your clothes if you're exposed to pollen or animals.