What Are Hives and Angioedema?
- Hives are slightly raised, smooth, flat-topped bumps that are usually slightly more reddish in color than the surrounding skin and cause severe itching.
- Hives come on suddenly due to an allergic reaction.
- One of every five people will have hives at some time in their lives.
- The medical term for hives is urticaria.
- Angioedema is an allergic reaction like hives, only the welts are larger and form in a deeper layer of the skin. Angioedema causes severe swelling, usually in the face, near the eyes and mouth.
- The swelling of angioedema can also occur in the inside of the throat, which is a dangerous situation because it can impair breathing by closing off the passage of air into the lungs.
- Hives and angioedema can occur together, but they usually do not.
- The most common rash for which people seek emergency medical care is hives.
- Hives and angioedema can happen at any age, in children or adults.
- Many different things can be triggers for hives and angioedema, including infections, stress, exercise, changes in the environment, and insect bites and stings. In up to half of cases, no specific trigger can be identified.
What Are Causes of Hives and Angioedema?
Hives and angioedema are reactions of the skin to histamine and other chemicals such as bradykinin, leukotriene C4, and prostaglandin D2. These chemicals act on blood vessels and other tissues to produce the clinical signs of hives and angioedema. This process 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. When the cause of a medical condition is not known, it is termed idiopathic. Idiopathic hives and angioedema are very common.
Some of the more common triggers of hives and angioedema include the following:
- Infections such as viral illnesses, especially in children
- Allergies to food, medications, cosmetics, soaps, and detergents
- Insect bites and stings
- Transfusions of blood or blood products
- Emotional and physical stress
- Physical agents such as sunlight, heat, cold, water, or pressure
- Allergies to animals, such as pet dander
Chronic hives are hives that lasts longer than six weeks. This can happen to anyone, but it is most common in women who are 40-60 years of age. Chronic hives can last for months or even years, but this is unusual. Although anyone can get hives, some people are at greater risk.
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
Allergies can best be described as:
What Are Symptoms and Signs of Hives and Angioedema?
Hives is a rash of smooth, raised, pink or reddish bumps of different sizes, called wheals. Hives appear suddenly. The wheals look somewhat like mosquito bites. They may cover all or part of the body and are usually very itchy.
- Hives usually break out 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 six 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.
- Hives are characterized by blanching, which means that the redness goes away and the area turns pale when pressure is applied.
- Dermographism may be present. Dermographism refers to the appearance of reddened areas like hives that appear after light scratching of the skin.
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 allergic reactions, which can be life-threatening emergencies, are called anaphylactic reactions. The symptoms and signs 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 heartbeat
- Dizziness or faintness
- Loss of consciousness
- Respiratory stridor, to and fro breathing that is strained in the throat
- The dizziness, faintness, and loss of consciousness are caused by dangerously low blood pressure, also called shock.
When Should Someone Seek Medical Care for Hives or Angioedema?
Contact a health care professional 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 the following symptoms along with hives or angioedema, you may be having an anaphylactic reaction. Go immediately to a hospital emergency department.
Other reasons to go to the emergency department include the following:
- Your hives or swelling do not improve after two to three days.
- You continue getting new hives after two days.
- Your symptoms do not get better with the treatment recommended by a health care professional.
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.
What Types of Doctors Treat Hives and Angioedema?
Primary-care specialists, including pediatricians, internists, and family practice specialists, may treat hives and angioedema. If a severe reaction occurs, an emergency-medicine specialist may treat hives and angioedema. For diagnosis and treatment of allergies over the long-term, an allergist-immunologist is typically involved.
How Do Health Care Professionals Diagnose Hives and Angioedema?
A health care professional 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, hair dyes, or 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, lupus, rheumatoid arthritis, liver disease, or kidney disease
- If there is the possibility you are pregnant
If a health care professional 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 is often not possible to identify the trigger of hives.
What Are Home Remedies for Hives and Angioedema?
- Stop any food, medicine, cosmetic, or other substance 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 a health care professional, until symptoms subside. These can be effective for mild episodes. Sedating antihistamines such as diphenhydramine may make one 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 with home remedies 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 one or two 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 such as an EpiPen, 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.
What Is the Medical Treatment for Hives and Angioedema?
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.
Could I Be Allergic? Discover Your Allergy Triggers
Are There Medications for Hives and Angioedema?
- 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 six to 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 loratadine (Claritin) and cetirizine (Zyrtec), are also available without a prescription. They need to be taken only every 12-24 hours and usually do not cause disruptive sleepiness.
- Prescription antihistamines may also be recommended by a doctor. These include hydroxyzine (Atarax, Vistaril) and cyproheptadine, both of which tend to cause drowsiness. Levocetirizine (Xyzal) is an antihistamine available by prescription that cause less drowsiness.
- 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 U.S. Food and Drug Administration (FDA) has not approved treating hives or angioedema with these drugs, but most physicians feel this is an appropriate use. Type H1 and H2 antihistamines may also be given together if necessary.
- Corticosteroids may be given over the short term in some situations. 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 many physicians feel this is an appropriate use.
- In March 2014, the U.S. FDA approved the monoclonal antibody omalizumab (Xolair) for treatment of chronic idiopathic urticaria (CIU) in adults and children aged 12 years or older for whom H1 antihistamine treatment does not relieve symptoms. It is a monoclonal antibody that selectively binds to immunoglobulin E (IgE) on mast cells and basophils, preventing other substances from binding to the IgE receptors on these cells and thereby inhibiting the allergic response. Omalizumab is administered as a subcutaneous injection once per month.
- For some patients who do not have relief with antihistamines or oral medications, topical medications like 5% doxepin cream (Zonalon) or capsaicin may be used.
Severe hives and most cases of angioedema may require more intense treatment.
- Epinephrine is a prescription drug, usually injected or given intravenously, 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.
What Follow-up Is Needed After Treatment of Hives and Angioedema?
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 a health care professional or return to the hospital if you have any of the following:
- Rash or swelling returns or gets worse
- Difficulty or severe side effects 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
Is It Possible to Prevent Hives and Angioedema?
It is not always possible to prevent hives and angioedema, but you can minimize your risk. Avoid exposure to any food, medicine, animals, 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.
What Is the Prognosis for Hives and Angioedema?
- 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 six weeks but is rare.
Where Can People Find Support Groups and Counseling for Hives and Angioedema?
Asthma and Allergy Foundation of America
1233 20th St NW, Suite 402
Washington, DC 20036
Where Can People Get More Information on Hives and Angioedema?
American Academy of Allergy, Asthma & Immunology
555 East Wells Street, Suite 1100
Milwaukee, WI 53202-3823
National Institute of Allergy and Infectious Diseases
6610 Rockledge Drive, MSC 6612
Bethesda, MD 20892-6612