Overview

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.

Symptoms

Hives

The welts associated with hives can be:

• Reddish
• 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

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.

Causes

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.

Risk factors

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

Complications

Severe angioedema can be life-threatening if swelling causes your throat or tongue to block your airway.

Prevention

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.

Diagnosis

Your doctor will examine any welts or areas of swelling and take a careful medical history to identify possible causes of your signs and symptoms. In some cases, you may be asked to undergo a skin-prick allergy test or other tests.

Treatment

If your symptoms are mild, you may not need treatment. Hives and angioedema often clear up on their own. But treatment can offer relief for intense itching, serious discomfort or symptoms that persist.

Medications

Treatments for hives and angioedema may include prescription drugs, including:

• Anti-itch drugs. The standard treatment for hives and angioedema are antihistamines that don't make you drowsy. These medications reduce itching, swelling and other allergy symptoms. They're available over-the-counter or by prescription.
• Anti-inflammatory drugs. For severe hives or angioedema, doctors may sometimes prescribe an oral corticosteroid drug — such as prednisone — to reduce swelling, redness and itching.
• Drugs that suppress the immune system. If antihistamines and corticosteroids are ineffective, your doctor might prescribe a drug capable of calming an overactive immune system.

Emergency situations

For a severe attack of hives or angioedema, you may need a trip to the emergency room and an emergency injection of epinephrine — a type of adrenaline. If you have had a serious attack or your attacks recur, despite treatment, your doctor may have you carry a pen-like device that will allow you to self-inject epinephrine in emergencies.

Lifestyle and home remedies

If you're experiencing mild hives or angioedema, these tips may help relieve your symptoms:

• Avoid triggers. These can include foods, medications, pollen, pet dander, latex and insect stings. If you think a medication caused your rash, stop using it and contact your primary care provider.
• Use an over-the-counter anti-itch drug. A nonprescription oral antihistamine, such as loratadine (Claritin), cetirizine (Zyrtec Allergy) or diphenhydramine (Benadryl Allergy, others), may help relieve itching. Consider whether you might prefer a type that doesn't cause drowsiness. Ask your pharmacist about options.
• Apply cold washcloth. Covering the affected area with a cold washcloth can help soothe the skin and prevent scratching.
• Take a comfortably cool bath. Find relief from itching in a cool shower or bath. Some people may also benefit from bathing in cool water sprinkled with baking soda or oatmeal powder (Aveeno, others), but this isn't a solution for long-term control of chronic itching.
• Wear loose, smooth-textured cotton clothing. Avoid wearing clothing that's rough, tight, scratchy or made from wool. This will help you avoid skin irritation.
• Avoid the sun. When outdoors, seek shade to help relieve discomfort.

Preparing for an appointment

You're likely to start by seeing your primary care doctor. In some cases when you call to set up an appointment, you may be referred immediately to a skin disease specialist (dermatologist) or to an allergy specialist.

What you can do

Here are some tips to help you get ready for your appointment.

• List your signs and symptoms, when they occurred, and how long they lasted.
• List any medications you're taking, including vitamins, herbs and supplements. Even better, take the original bottles and a list of the doses and directions.
• List questions to ask your doctor.

For hives and angioedema, questions you may want to ask include:

• What is likely causing my symptoms?
• Do I need any tests to confirm the diagnosis?
• What are other possible causes for my symptoms?
• Is my condition likely temporary or chronic?
• What is the best course of action?
• What are the alternatives to the primary approach that you're suggesting?
• Do I need prescription medication, or can I use over-the-counter medications to treat the condition?
• What results can I expect?
• Can I wait to see if the condition goes away on its own?

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

• When did you first begin experiencing symptoms?
• What did your skin reaction look like when it first appeared?
• Have your symptoms changed over time?
• Have you noticed anything that makes your symptoms worse or better?
• Do your skin lesions mainly itch, or do they burn or sting?
• Do your skin lesions go away completely without leaving a bruise or a mark?
• Do you have any known allergies?
• Have you ever had a similar skin reaction before?
• Have you tried a new food for the first time, changed laundry products or adopted a new pet?
• What prescriptions, over-the-counter medications and supplements are you taking?
• Have you started taking any new medications or started a new course of a medication you've taken before?
• Has your overall health changed recently? Have you had any fevers or lost weight?
• Has anyone else in your family ever had this kind of skin reaction? Do other family members have any known allergies?
• What at-home treatments have you used?