Signs and symptoms

Acute hives can last from less than a day to up to 6 weeks, whereas chronic hives last more than 6 weeks — sometimes occurring for months to years at a time. Often, angioedema and hives occur together.

Signs and symptoms of hives include:

• Raised, red, often itchy welts of various sizes that appear and disappear on your skin
  
  
• Wheals that commonly occur on areas of the body where clothes rub your skin
• Wheals that tend to occur in batches

Signs and symptoms of HAE include:

• Sudden and severe swelling of your 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 your airway

Causes

Hives and angioedema are triggered when certain cells (mast cells) — which line the blood vessels in your skin — 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 and milk are frequent offenders.
  
  
• Medications. Almost any medication may cause hives or angioedema, but more common culprits include penicillin, aspirin, ibuprofen (Advil, Motrin, others), angiotensin-converting enzyme (ACE) inhibitors, and antibiotics containing sulfa and opiates.
  
  
• Other allergens. Other substances that can cause hives and angioedema include pollen, animal dander, latex and substances injected into your skin from insect stings.

Additional triggers that may produce hives or angioedema include:

• Physical factors. Environmental elements also can result in the release of histamine with subsequent hives or angioedema in some individuals. Examples of these factors include elements such as heat, cold, sunlight, water, pressure on the skin, emotional stress and exercise.
  
  
• Dermatographism. The name of this rare condition literally means to "write on the skin." When pressure is applied to the skin or the skin is scratched, raised lines appear on those areas due to allergy-based angioedema that leads to swelling beneath the skin.

In addition to these triggers, hives and angioedema sometimes may occur in response to the body's production of antibodies. Some examples of situations in which this might occur include blood transfusions, immune system disorders, such as lupus or cancer, certain thyroid disorders and infections, such as hepatitis A or B, 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.

Food allergy Dermatographia (skin writing) Lupus

Risk factors

You may be at greater risk of hives and angioedema if:

• You've experienced hives or angioedema before.
  
  
• You've experienced other allergic reactions.
  
  
• You have a family history of hives or angioedema.
  
  
• You have a family history of hereditary angioedema.

When to seek medical advice

Mild hives and angioedema usually aren't life-threatening, and often you can treat hives and angioedema at home. However, seek emergency care if you feel lightheaded, have difficulty breathing, or if hives or swelling doesn't respond to treatment or continues to appear for more than a couple of days.

Screening and diagnosis

It's sometimes impossible to determine the cause of hives or angioedema. 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 over a period of 2 to 4 weeks. It's important to tell your doctor about all medications you take, including over-the-counter (OTC) drugs and herbal remedies, even if you don't take them every day. Your doctor may also want to conduct allergy tests, such as skin tests.

If your doctor suspects HAE, he or she may ask for blood tests to check for levels and function of specific blood proteins. If allergy to food, latex, animal dander, pollen or medication is suspected, your doctor may recommend allergy skin or blood tests.

Allergy skin tests: Diagnosing your allergies

Complications

Hives and angioedema can, at the least, cause itching and discomfort. In more serious cases — where swelling occurs inside your mouth or throat — complications can include difficulty breathing or loss of consciousness. 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 death. This occurs rapidly.

Anaphylaxis

Treatment

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)
  
  
• Clemastine (Tavist, others)
  
  
• Loratadine (Claritin, Alavert)

Antihistamines such as diphenhydramine, chlorpheniramine and clemastine may cause drowsiness. Loratadine usually doesn't cause drowsiness.

Prescription medications

• Fexofenadine (Allegra)
  
  
• Cetirizine (Zyrtec)
  
  
• Hydroxyzine (Hyzine)

Occasionally, for severe hives or angioedema, physicians may prescribe an oral corticosteroid drug — such as oral prednisone — which can help lessen swelling, redness and itching.

Although useful in treating hives and angioedema, these medications are often ineffective in treating hereditary angioedema. Medications used specifically to treat HAE on a long-term basis include certain androgens, such as stanozolol (Winstrol) and danazol (Danocrine), which help regulate levels of blood proteins.

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.

Complementary and alternative allergy treatments and tests

Prevention

To lower the likelihood of experiencing hives or angioedema, avoid substances, such as certain foods or medications, or situations, such as temperature extremes, that have triggered past allergic attacks. If you suspect foods of 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.

Self Care

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

• Avoid irritating affected areas.
  
  
• Take cool showers.
  
  
• Apply cool compresses.
  
  
• Wear loose, light clothing.
  
  
• Minimize vigorous activity, which can release more irritants into the skin.
  
  
• Use OTC antihistamines to help relieve the itching.

— May 5, 2003 —