Hives and Angioedema

Hives is an allergic skin reaction that comes on suddenly. The hives themselves are slightly raised, smooth, flat-topped bumps called wheals (look like mosquito bites) and welts that are usually more red in color than the surrounding skin and cause severe itching.

Angioedema is like hives, only the welts are larger and form at a deeper layer in the skin. This causes severe swelling, usually in the face, near the eyes and mouth. The swelling can also occur in the inside of the throat, which is a dangerous situation because it can close off the passage of air into the lungs.

Hives and angioedema can occur together, but they usually do not. Hives is the most common rash for which people seek emergency medical care. One of every 5 people will have hives at some time in their lives. Angioedema is less common. Hives and angioedema can happen at any age.

Medical professionals refer to hives as urticaria.

This article does not refer to an uncommon and more serious condition, hereditary angioedema. Hereditary angioedema involves swelling over the entire body, including some internal organs.

Hives and angioedema are reactions of the skin to the release of histamine or other chemicals into the blood. This is often, although not always, due to an allergic reaction.

• There are many causes of hives and angioedema. At least half the time, the specific cause cannot be determined.



• Some of the more common triggers are the following:
  
  
  • Infections such as viral illnesses, especially in children
  
  
  
  • Allergies to food, medications, cosmetics, soaps, and detergents
  
  
  
  • Insect stings and bites
  
  
  
  • Transfusions of blood or blood products
  
  
  
  • Emotional and physical stress
  
  
  
  • Physical agents such as sunlight, heat, cold, water, or pressure


• Chronic hives is a case of hives that lasts longer than 6 weeks. This can happen to anyone, but it is most common in women aged 40-60 years. Chronic hives can last for months or even years, but this is unusual.



• Risk factors for hives and angioedema include the following:
  
  
  • A previous case of hives or angioedema
  
  
  
  • A previous allergic reaction
  
  
  
  • Family members who have hives or angioedema

• Hives is a rash of smooth, raised, pink or reddish bumps of different sizes called wheals that comes on suddenly. The wheals look something like mosquito bites. They may cover all or part of the body and are usually very itchy.
  
  
  • Hives usually appear first on the covered areas of the skin such as the trunk and upper parts of the arms and legs.
  
  
  
  • Wheals appear in batches. Each wheal may last from a few minutes to 6 hours. As wheals disappear, new ones form. A case of hives usually lasts at most a few days.
  
  
  
  • Hives are usually patchy at first, but the patches may run together until the hives cover most of the body.
  
  
  
  • The patches can be small or large. They are usually irregular in shape. Often, the patches have clearing of the redness in the center with a red halo or flare at the edges.
  
  
  
  • The itching is often very intense.


• Angioedema is related to hives but has a different appearance. Angioedema describes marked swelling, usually around the eyes and mouth. It may also involve the throat, tongue, hands, feet, and/or genitals.
  
  
  • The skin may appear normal, without hives or other rash.
  
  
  
  • The eyes may appear swollen shut.
  
  
  
  • The swellings usually do not itch, but may be painful or burning.
  
  
  
  • The swellings may not be symmetrical (the same on both sides of the body).
  
  
  
  • Like hives, the swelling of angioedema can go away on its own.



• Other, more severe allergic reactions may occur with hives or angioedema. A reaction may start with hives or angioedema and then progress rapidly to more serious symptoms. The most serious reactions, which can be life-threatening emergencies, are called anaphylactic reactions. The symptoms of an anaphylactic reaction include the following:
  
  
  • Swelling of the face, tongue, or throat
  
  
  
  • Wheezing, a raspy sound when you breathe
  
  
  
  • Difficulty breathing
  
  
  
  • Difficulty swallowing
  
  
  
  • Tightness in the throat or chest
  
  
  
  • Rapid or irregular heart beat
  
  
  
  • Dizziness or faintness
  
  
  
  • Loss of consciousness



• The dizziness, faintness, and loss of consciousness are caused by dangerously low blood pressure, also called shock.

Contact your health care provider if you have hives or angioedema. After hearing your symptoms, he or she may want to see you for an office visit.

If you are having any of these symptoms along with hives or angioedema, you may be having an anaphylactic reaction. Go immediately to a hospital emergency department.

• Difficulty with breathing or swallowing

• Wheezing

• Abdominal pain, vomiting, or diarrhea

• General weakness

• Feeling dizzy, light-headed, or faint

Other reasons to go to the emergency department:

• Your hives or swelling do not improve after 2-3 days.

• You continue getting new hives after 2 days.

• Your symptoms do not get better with the treatment recommended by your health care provider.

Do not drive yourself; if no one is available to take you right away, call 911 for emergency transport. While waiting for the ambulance to arrive, begin self-treatment.

Your health care provider will examine you and ask questions about how the hives or angioedema started. Tell him or her about the following:

• Any medicines (prescription and nonprescription) you have been taking even if you stopped them in the past few days

• Any dietary supplement or herbs you take, even if only sometimes, and the last time you took them

• Any new or unusual foods, soaps, detergents, and cosmetics

• Any allergies that you know about

• Any recent illnesses you have had such as sore throat, cough, runny nose, vomiting, or diarrhea

• Any chronic illnesses such as diabetes, liver disease, or kidney disease

• If there is the possibility you are pregnant

If your health care provider cannot tell what triggered your hives or angioedema, he or she may recommend that you see an allergy specialist (allergist). Even using special skin tests, however, it may not be possible to identify the trigger.

|Self-Care at Home|

• Stop any food or medicine identified as the cause of the hives or angioedema.



• In very mild cases, no treatment at all may be required.



• If symptoms are making you uncomfortable, take a nonprescription antihistamine, such as diphenhydramine (Benadryl), by mouth, per the package instructions or as directed by your health care provider, until symptoms subside. These can be effective for mild episodes. CAUTION: Antihistamines may make you too drowsy to drive or operate machinery safely.



• Cool compresses or baths may help with the discomfort.



• Avoid hot baths or showers.



• Avoid direct sunlight.



• Wear light, loose-fitting clothing.



• Avoid strenuous activity or anything that might cause sweating.



• Try to relax and reduce stress.

Severe reactions: Do not attempt to treat severe reactions or to wait it out at home. Go immediately to the nearest emergency department or call an ambulance. Here are some things you can do while waiting for the ambulance:

• Try to stay calm.



• If you can identify the cause of the reaction, prevent further exposure.



• Take an antihistamine, such as 1-2 tablets or capsules of diphenhydramine (Benadryl), if you can swallow without difficulty. The liquid form of diphenhydramine (Benadryl) can also be used at 2-4 teaspoons (10-20 mL) per dose.



• If you are wheezing or having difficulty breathing, use an inhaled bronchodilator, such as albuterol (Proventil), if one is available. These inhaled medications dilate the airway.



• If you are feeling light-headed or faint, lie down and raise your legs higher than your head to help blood flow to your brain.



• If you have been given an epinephrine kit, inject yourself as you have been instructed. The kit provides a premeasured dose of epinephrine, a prescription drug that rapidly reverses the most serious symptoms (see Follow-up).



• Bystanders should administer CPR to a person who becomes unconscious and stops breathing or does not have a pulse.



• If at all possible, you or your companion should be prepared to tell medical personnel what medications you take and your allergy history.

|Medical Treatment|

The treatment of hives depends on the severity of the symptoms. For mild to moderately severe localized symptoms, a nonprescription antihistamine by mouth is usually adequate, along with skin care measures for comfort. For more severe cases, an injection or short course of a corticosteroid may be needed to rapidly reduce swelling and itching.

|Medications|

• Short-acting type H1 antihistamines: These medications, including diphenhydramine (Benadryl), are the primary treatment of mild cases of hives and angioedema. These are available without a prescription and are inexpensive. However, they must be taken every 6-12 hours and cause sleepiness, which can interfere with normal activity.



• Long-acting H1 antihistamines: These may also be used for mild cases of hives and angioedema. These drugs, which include fexofenadine (Allegra) and cetirizine (Zyrtec), are available by prescription. They are more expensive than nonprescription antihistamines but need to be taken only every 12-24 hours and usually do not cause disruptive sleepiness. The long-acting and nonsedating H1 antihistamine loratadine (Claritin) is now available without a prescription and one 10 mg tablet per day may be an alternative for some patients.



• Type H2 antihistamines: Drugs such as ranitidine (Zantac), cimetidine (Tagamet), and famotidine (Pepcid) have also been found to improve the rash and swelling when given with the type H1 antihistamines. Type H2 antihistamines were developed to treat ulcers. The US Food and Drug Administration (FDA) has not approved treating hives or angioedema with these drugs, but most physicians feel this is an appropriate use.



• Corticosteroids: These drugs suppress the allergic response of the immune system. They may be given by injection or by mouth. Examples are prednisone (Deltasone), methylprednisolone (Medrol), and dexamethasone (Decadron). They reduce the chance of the rash coming back. They also relieve symptoms, such as swelling and inflammation, but may take a few hours to work. For severe situations, corticosteroids may be given by an injection or infused through an IV line.



• H1- and H2-blocking drugs: Hives that do not respond to type H1 and H2 antihistamines may be treated with another type of drug. An example is doxepin (Sinequan). These drugs are intended as antidepressants, but they also have strong antihistamine effects, blocking both H1 and H2 histamine reactions. They can be very sedating. The FDA has not approved treating hives with these drugs, but most physicians feel this is an appropriate use.

Severe hives and most cases of angioedema may require more intense treatment.

• Epinephrine is a prescription drug, usually injected or given through an IV line, that rapidly reverses the most severe allergic reactions, including anaphylactic shock.



• IV fluids, usually saline solution, are given to increase blood pressure.



• Oxygen may be given through a tube in the nose or via face mask in case of breathing trouble.



• Other medications may be given as needed to reverse symptoms or raise blood pressure.



• People who have angioedema usually need hospitalization as the recurrence risk is high, even with improvement after the initial treatment. Some cases of severe hives may also require hospitalization.

|Follow-up|

Take all prescribed medicines as directed except for those drugs you are instructed to take only as needed. This will reduce the possibility of the hives or swelling coming back.

Contact your health care provider or return to the hospital if you have any of the following:

• Rash or swelling returns or gets worse

• Difficulty with your medicines

• New symptoms

• Sores or swelling of the mouth, tongue, or throat

• Fever or chills

• Difficulty with breathing or swallowing

• Vomiting or diarrhea

|Prevention|

Avoid exposure to any food, medicine, or physical agent that has been identified to cause your hives or angioedema.

Reducing emotional and physical stress may help. In rare cases, you may need to take antihistamines or other medicines for an extended time to prevent further hives or swelling.

|Outlook|

• Hives and angioedema may be very uncomfortable but will not cause serious harm.
  
  
• The hives will not leave scars.
  
  
• Most people do well with treatment.
  
  
• Hives and angioedema usually will last only a few hours to a few days. Chronic hives lasts longer than 6 weeks but is rare.

|Support Groups and Counseling|

Asthma and Allergy Foundation of America
1233 20th St NW, Suite 402
Washington, DC 20036
(202) 466-7643

American Academy of Allergy, Asthma & Immunology
555 East Wells Street, Suite 1100
Milwaukee, WI 53202-3823
(800) 822-2762

National Institute of Allergy and Infectious Diseases
6610 Rockledge Drive, MSC 6612
Bethesda, MD 20892-6612

|Web Links|

American Academy of Allergy Asthma & Immunology, Tips to Remember: Allergic Skin Conditions

MedlinePlus, Hives

MedlinePlus, Angioedema

MayoClinic, Hives and angioedema

hives and angioedema, allergic reaction, allergy, allergic skin reaction, facial swelling, nettle rash, skin allergy, urticaria, wheals, welts, hives, angioedema, anaphylactic reaction, swelling in the throat, food allergies, medication allergies, stress, chronic hives

Author: Richard E Daily, MD, FAAEM, Staff Physician, Department of Emergency Medicine, Skagg's Community Health Center.

Editors: Scott H Plantz, MD, FAAEM, Research Director, Assistant Professor, Department of Emergency Medicine, Mount Sinai School of Medicine; Mary L Windle, Pharm D, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Pharmacy Editor, .com, Inc; Ron Fuerst, MD, Clinical Assistant Professor, Department of Pediatrics, University of South Carolina College of Medicine; Director, Children's Emergency Center, Children's Hospital of Richland Memorial Hospital.