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Hives and angioedema
By Mayo Clinic staffMayo Clinic Health Manager
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Definition
Hives — also known as urticaria (ur-tih-KAR-e-uh) — are raised, red, itchy welts (wheals, or swellings) of various sizes that seem to appear and disappear on your skin. Angioedema, a type of swelling, causes large welts deeper in your skin, especially near your eyes and lips.
In most cases, hives and angioedema are harmless and don't leave any lasting marks, even without treatment. The most common treatment for hives and angioedema is antihistamine medications. Serious angioedema can be life-threatening if swelling causes your throat or tongue to block your airway and leads to loss of consciousness.
Symptoms
Hives
Signs and symptoms of hives include:
- Raised, red or white welts (wheals, or swellings) of various sizes
- A single welt or group of welts that can cover large areas of skin
- Welts that resolve while new welts erupt, making it seem as if the condition "moves"
- Burning or stinging in the affected area
- Itching, which may be severe
Hives can be either acute or chronic. By definition, acute hives can last from less than a day to up to six weeks, whereas chronic hives last more than six weeks — sometimes occurring for months to years at a time.
Angioedema
Angioedema is similar to hives but occurs deeper in the skin. Signs and symptoms of angioedema include:
- Large, thick, firm welts
- Swelling of the skin
- Blisters (bullae) in areas of severe swelling
- Pain or warmth in the affected areas
- Difficult breathing or swallowing, in severe cases
Angioedema often appears near your eyes or lips, but can also develop on your hands, feet, genitalia or inside your throat. Angioedema and hives can occur separately or at the same time.
Hereditary angioedema is a more serious — yet uncommon — condition that can cause sudden, severe and rapid swelling of your face, arms, legs, hands, feet, genitalia, digestive tract and airway. Signs and symptoms of hereditary angioedema include:
- Sudden and severe swelling of the face, arms, legs, hands, feet, genitalia, digestive tract and airway
- Abdominal cramping as a result of digestive tract swelling
- Difficulty or obstructed breathing due to swelling of the airway
When to see a doctor
Mild hives and angioedema usually aren't life-threatening. You can usually treat mild cases at home.
See your doctor if the hives or angioedema doesn't respond to treatment or if your symptoms continue to appear for more than a couple of days. Seek emergency care if you:
- Feel lightheaded
- Have difficulty breathing
- Feel your throat is swelling
Causes
Hives and angioedema are caused by inflammation in the skin. In some cases, hives and angioedema are triggered when certain cells (mast cells) release histamine and other chemicals into your bloodstream and skin.
Allergic reactions to medications or foods can cause acute hives or angioedema. Many allergens have been identified. Examples include:
- Foods. Many foods can cause problems in sensitive people, but shellfish, fish, nuts, eggs, chocolate and milk are frequent offenders. Food additives, such as salicylates and sulfites, are other potential allergens.
- Medications. Almost any medication may cause hives or angioedema; common culprits include penicillin, aspirin, ibuprofen (Advil, Motrin, others) and blood pressure medications.
- Other allergens. Other substances that can cause hives and angioedema include direct contact with pollen, animal dander, latex and insect stings.
Additional triggers that may produce hives or angioedema include:
- Physical factors. Environmental factors can result in the release of histamine with subsequent hives or angioedema in some people. Examples of these factors include heat, cold, sunlight, water, pressure on the skin, emotional stress and exercise.
- Dermatographia. The name of this condition literally means "write on the skin." When pressure is applied to the skin or the skin is scratched, raised lines appear on those areas due to histamine-based angioedema that leads to swelling beneath the skin.
In addition to these triggers, hives and angioedema sometimes occur in response to your body's production of antibodies. This may occur because of blood transfusions; immune system disorders, such as lupus or cancer; certain thyroid disorders; infections, such as hepatitis; or even a cold.
Hereditary angioedema is an inherited form of angioedema and is related to low levels or abnormal functioning of certain blood proteins (C1 inhibitors). These inhibitors play a role in regulating how your immune system functions.
Risk factors
You may be at greater risk of hives and angioedema if you:
- Have had hives or angioedema before
- Have had other allergic reactions
- Have a disorder associated with hives and angioedema, such as lupus, lymphoma or thyroid disease
- Have a family history of hives, angioedema or hereditary angioedema
Complications
Hives and angioedema can cause:
- Itching
- Discomfort
In more serious cases — such as when swelling occurs inside your mouth or throat — complications can include:
- Difficulty breathing
- Loss of consciousness
- Anaphylactic shock
Anaphylactic shock (anaphylaxis) is a serious allergic reaction involving your heart or lungs. Your bronchial tubes narrow, it's difficult to breathe, and your blood pressure drops, causing dizziness and perhaps loss of consciousness or even death. Anaphylactic shock occurs rapidly, and requires immediate medical care.
Preparing for your appointment
You're likely to start by first seeing your family doctor or primary care doctor. However, in some cases when you call to set up an appointment, you may be referred immediately to a skin disease specialist (dermatologist).
Because appointments can be brief and there's often a lot of ground to cover, it can help to be well prepared. Here are some tips to help you get ready for your appointment and what to expect from your doctor.
What you can do
Write down your signs and symptoms, when they occurred and how long they lasted. Also, make a list of all medications, including vitamins, herbs and over-the-counter drugs that you're taking. Even better, take the original bottles and a written list of the dosages and directions.
Write down questions that you want to ask your doctor. Don't be afraid to ask questions or to speak up when you don't understand something your doctor says. For hives and angioedema, questions you may want to ask include:
- What is likely causing my symptoms?
- Are tests needed 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 the welts look like when they first started?
- Have your symptoms changed over time?
- What, if anything, appears to worsen your symptoms?
- What at-home treatments have you used?
- What prescription and over-the-counter medications are you taking?
Tests and diagnosis
Your doctor will begin by asking you about your medical history. This may include asking you to create a detailed diary of exposure to possible irritants. It's important to tell your doctor about all medications you take, including over-the-counter (nonprescription) drugs and herbal remedies, even if you don't take them every day.
If the cause of your hives or angioedema isn't apparent or if your symptoms recur often, your doctor may recommend an allergy skin test.
- Puncture, prick or scratch test (percutaneous). In this test, which is the type of skin test most commonly performed, tiny drops of purified allergen extracts are pricked or scratched into your skin's surface. This test is usually performed to identify allergies to pollen, animal dander, foods, insect venom and penicillin.
- Intradermal test (intracutaneous). Purified allergen extracts are injected into the skin of your arm. This test is usually performed if your doctor suspects that you're allergic to insect venom or penicillin.
- Patch test (epicutaneous). An allergen is applied to a patch, which is then placed on your skin. This test can identify substances that cause a reaction when coming in contact with your skin. Tested substances may include latex or medications.
If your doctor suspects hereditary angioedema, he or she may ask for blood tests to check for levels and function of specific blood proteins.
Treatments and drugs
If your symptoms are mild, you may not need treatment. The standard treatment for hives and angioedema is antihistamines, which block the symptom-producing release of histamine. These include:
Nonprescription medications
- Diphenhydramine (Benadryl, others)
- Chlorpheniramine (Chlor-Trimeton, others)
- Loratadine (Alavert, Claritin)
- Cetirizine (Zyrtec)
Antihistamines such as diphenhydramine and chlorpheniramine may cause drowsiness. Loratadine usually doesn't cause drowsiness.
Prescription medications
- Desloratadine (Clarinex)
- Fexofenadine (Allegra)
- Hydroxyzine (Vistaril)
- Levocetirizine (Xyzal)
Occasionally for severe hives or angioedema, doctors may prescribe an oral corticosteroid drug — such as prednisone — which can help lessen swelling, redness and itching.
Treatment for hereditary angioedema
Although useful in treating hives and angioedema, these medications are often ineffective in treating hereditary angioedema. Medications used specifically to treat hereditary angioedema on a long-term basis include certain androgens, such as danazol, that help regulate levels of blood proteins. Additionally, clinical trials testing new medications to treat hereditary angioedema are ongoing.
Emergency situations
For a severe attack of hives or angioedema, you may need an emergency injection of adrenaline (epinephrine) and a trip to the emergency room. If you have repeated attacks, despite treatment, your doctor may prescribe — and instruct you how to use — adrenaline to carry with you for use in emergency situations.
Lifestyle and home remedies
If you're experiencing mild hives or angioedema, these tips may help relieve your symptoms:
- Try to identify and avoid substances that irritate your skin or that cause an allergic reaction. These can include foods, medications, pollen, pet dander, latex and insect stings.
- Use over-the-counter antihistamine. A nonprescription oral antihistamine, such as diphenhydramine (Benadryl, others) or loratadine (Claritin) may help relieve itching.
- Apply cool, wet compresses. Covering the affected area with bandages and dressings can help soothe the skin and prevent scratching.
- Take a comfortably cool bath. To relieve itching, sprinkle the bath water with baking soda, uncooked oatmeal or colloidal oatmeal — a finely ground oatmeal that is made for the bathtub (Aveeno, others).
- Wear loose, smooth-textured cotton clothing. Avoid clothing that's rough, tight, scratchy or made from wool. This will help you avoid irritation.
Prevention
To lower your likelihood of experiencing hives or angioedema, take the following precautions:
- Avoid known triggers. These may include certain foods or medications, or situations, such as temperature extremes, that have triggered past allergic attacks.
- Keep a diary. If you suspect foods are causing the problem, keep a food diary. Be aware that some foods may contain ingredients that are listed by less common names on the label.
- Urticaria — hives. American Academy of Dermatology. http://www.aad.org/public/publications/pamphlets/skin_urticaria.html. Accessed Oct. 22, 2008
- Allergic skin conditions. American Academy of Allergy, Asthma and Immunology. http://www.aaaai.org/patients/publicedmat/tips/allergicskinconditions.stm. Accessed Oct. 22, 2008.
- Habif TP. Urticaria and angioedema. In: Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 4th ed. Philadelphia, Pa.: Mosby Inc; 2004. http://www.mdconsult.com/das/book/body/108133988-3/0/1195/29.html#4-u1.0-B0-323-01319-8..50008-X--cesec5_428. Accessed Oct. 22, 2008.
- Bingham CO III. An overview of angioedema. http://www.uptodate.com/home/index.html. Accessed Oct. 22, 2008.
- Bingham CO III. Etiology and diagnosis of urticaria. http://www.uptodate.com/home/index.html. Accessed Oct. 22, 2008.
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- Simmons FER, et al. Anaphylaxis: Rapid recognition and treatment. http://www.uptodate.com/home/index.html. Accessed Oct. 30, 2008.
- Atkinson JP, et al. Pathogenesis and clinical manifestations of hereditary angioedema. http://www.uptodate.com/home/index.html. Accessed Oct. 30, 2008.
