Hives are raised red bumps (welts) or splotches on the skin. They are a type of swelling on the surface of your skin. They happen when your body has an allergic reaction to an allergen, a substance that’s harmless to most people. But can also occur in autoimmune conditions or systemic conditions, if hives last for a prolonged period of time.
Hives may be itchy, or you might feel them burning or stinging. They can be as small as a pinprick or as big as a dinner plate. The medical name for hives is urticaria.
Sometimes, the welts from hives join together to form larger areas called plaques. Hives tend to fade within 24 hours, although they may be noticeable for several days or longer.
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| Hives (urticaria) |
What is swelling (angioedema)?
Angioedema is a kind of swelling that can be related to hives, but can be an isolated event. It most often causes swelling in deep layers of tissue around the eyes, lips and face. Your hands, feet, throat, intestines and genitals may also swell.
People who get hives may get angioedema at the same time. Sometimes people have angioedema without hives.
Swelling from angioedema can be itchy, and can sometimes be painful. It usually goes away in a day or two. In extreme situations, your throat, airway and digestive tract might swell. These reactions can be life-threatening.
How common are hives and angioedema?
About 20% of people will develop hives at least once. Angioedema by itself occurs less often.
Who’s most likely to get hives (urticaria) or angioedema?
Anyone can get hives or angioedema. Hives are more common than angioedema. People who react to many different types of allergens may get hives frequently. Some people get hives just once or only a few times in their lives.
What are the types of hives (urticaria) and angioedema?
There are different types of hives (urticaria) and angioedema, including:
- Acute: Hives or swelling that last for less than six weeks are considered acute, meaning they come on suddenly. Allergic reactions to certain foods or medications often cause acute hives and swelling.
- Chronic: When hives linger for more than six weeks, the condition is chronic. In 95% of chronic conditions, nobody knows what causes them, though it is thought to be autoimmune in nature.
- Physical: Some people develop hives and swelling in specific situations. Hives might pop up when you’re in the cold, heat or sun. Some people react to vibrations or pressure, or exercise and sweating. Physical hives usually appear within an hour after exposure.
What causes hives (urticaria) and swelling (angioedema)?
Allergens can causes these reactions. An allergen is a substance your body doesn’t like, and your body’s immune system reacts by releasing chemicals called histamines. Histamines are a chemical made by allergy cells (mast cell) and other immune cells (eosinophils, basophils, etc) that goes into overdrive to get rid of the allergen. But your body may respond to the flood of histamines by having an allergic reaction that causes hives and swelling.
People get hives and angioedema from all kinds of things, including:
- Airborne allergens like tree and grass pollen, mold spores and pet dander.
- Bacterial infections, such as strep throat and urinary tract infections.
- Food allergies to milk, peanuts and tree nuts, eggs, fish and shellfish.
- Insect stings.
- Medication allergies, including non-steroidal anti-inflammatory drugs (NSAIDs), codeine and blood pressure medicine, especially ACE inhibitors.
- Quick changes in body temperature due to heat, cold or physical activity.
- Viral infections, such as the common cold or mononucleosis.
- Allergies to other materials, like latex or detergents.
- Hormonal issues, like changes in your body because of pregnancy, menopause or thyroid disease.
- Autoimmune conditions.
What are the symptoms of hives (urticaria)?
Hives look different depending on the person and the situation. They can show up anywhere on your body. Signs of hives include:
- Red, raised welts or bumps on the skin.
- Blanching (the center of the hive turns white when pressed).
- Itchy skin.
- Swelling (angioedema).
What are the symptoms of swelling (angioedema)?
Signs of angioedema include:
- Puffy or swollen face, especially the eyes and mouth.
- Digestive problems, such as abdominal pain, diarrhea or nausea and vomiting.
- Swollen hands, feet or genitals.
- Swelling in the mouth, throat or airway that may make it harder to breathe.
How are hives (urticaria) and swelling (angioedema) diagnosed?
Your doctor can diagnose hives and swelling by looking at your skin. Allergy tests can help identify what’s triggering a reaction. Knowing the cause can help you avoid allergens, hives and swelling. Allergy tests include:
- Skin tests: During this test, healthcare providers test different allergens on your skin. If your skin turns red or swells, it means you’re allergic to that substance. This type of allergy test is also called a skin prick or scratch test. Skin testing is not commonly done if hives are chronic in nature.
- Blood tests: A blood test checks for specific antibodies in your blood. Your body makes antibodies to fight off allergens. The process is part of your immune system — but if your body makes too many, it can cause hives and swelling.
How are hives (urticaria) and swelling (angioedema) managed or treated?
Most of the time, hives and swelling go away without treatment. Your healthcare provider might recommend medications and at-home care to help you feel better and lower your chances of having hives again. Treatments include:
- Allergy medications: Medicines called antihistamines block histamine’s effects on your body. Antihistamines relieve itching from hives and prevent allergic reactions. Some antihistamines react fast, like diphenhydramine (Benadryl®). Depending how severe the hives are, your healthcare provider may recommend daily over-the-counter (OTC) or prescription allergy medications, like loratadine (Claritin®). fexofenadine (Allegra®), cetirizine (Zyrtec®) or levocetirizine (Xyzal®).
- Allergy shots: For hard-to-treat chronic hives, your healthcare provider may recommend a monthly injection of a drug called omalizumab (Xolair®). This medication blocks the body’s allergy antibody, immunoglobin E (IgE), from causing allergy reactions. People with severe allergies can make too much IgE, leading to problems like hives and asthma.
- At-home treatments: To relieve hives, you can take a cool bath or shower, wear loose-fitting clothing and apply cold compresses. An OTC hydrocortisone cream, such as Cortizone®, can relieve itching and swelling.
- Epinephrine: Severe allergic reactions and swelling can lead to a life-threatening condition called anaphylaxis. Symptoms include hives, swelling, shortness of breath, wheezing, vomiting and low blood pressure. People experiencing anaphylaxis need an immediate epinephrine injection (EpiPen®) to open a swollen airway.
- Oral steroids: Corticosteroids, such as prednisone, can relieve hive symptoms that don’t respond to antihistamines.
What are the complications of hives (urticaria) and swelling (angioedema)?
Anyone who has a severe allergic reaction could have life-threatening swelling (angioedema) of the airways — your throat and lungs. This condition is known as anaphylaxis. It can potentially close off the airways, resulting in death.
Anaphylaxis is often triggered by a severe allergic reaction to a certain food, like peanuts and tree nuts, or a bee sting. People having anaphylaxis need an immediate shot of epinephrine, such as injectable epinephrine (EpiPen® or AUVI-Q®). Epinephrine opens airways, raises blood pressure and reduces hives and swelling. If epinephrine is used outside of the medical setting, a trip to the ER is warranted, since symptoms can return if epinephrine wears off.
How can I prevent hives (urticaria) and swelling (angioedema)?
Allergy tests can help your healthcare provider figure out which substances bring on hives and swelling. Once you know your triggers, you can avoid them. You may want to:
- Cut certain foods or liquids out of your diet.
- Reduce exposure to airborne allergens.
- Switch to detergents and soaps without scents or dyes.
- Avoid extreme changes in temperature.
- Relax and take a break when you’re stressed or overworked.
- Wear loose-fitting, lightweight clothing.
What is the prognosis (outlook) for people with hives and swelling?
For most people, hives don’t cause serious problems. Children often outgrow allergies that cause hives.
For some people, angioedema can cause anaphylaxis — severe swelling of the airways and lungs. People with this life-threatening condition should carry injectable epinephrine (EpiPen®) to treat severe allergic reactions.
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