Hives, or urticaria, are “itchy, raised welts” that can sting or hurt. They are usually triggered by an allergic reaction to food, medication, or environmental irritants. Most cases are acute and “go away on their own,” but chronic hives or severe reactions are more serious.

Hives happen when the body releases histamines during an allergic reaction, causing “swelling, itching,” and welts. Common triggers include “pollen, medications, food, animal dander, and insect bites.” Stress, tight clothing, exercise, infections, and temperature extremes can also cause hives. Often, “the actual cause of hives can’t be determined.”

People with allergies are most at risk. Taking medication, exposure to allergens, or being ill can also make you more vulnerable.

Chronic hive symptoms include “batches of welts,” painful swelling around the face, intense itching, and symptoms that “persist for more than six weeks and recur often.”

Doctors usually diagnose hives through a physical exam and may use blood or skin tests. Mild cases can be treated with “antihistamines,” cool baths, and avoiding irritants. If you experience severe hives or symptoms of anaphylaxis, such as “trouble breathing” or “swelling of the tongue,” seek emergency care immediately.