Hives (Urticaria) and Swelling (Angiodema)
What are hives (urticaria)?
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.
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.