Hives, medically known as urticaria, are raised, red, itchy welts that appear suddenly on the skin. They usually happen as an allergic reaction or response to irritants. These welts can be small or large and sometimes merge to form bigger patches. Although this condition is generally harmless, they can cause a lot of discomfort and distress—especially when they come back often or last a long time. The condition can be acute, clearing up within days or weeks, or chronic, lasting six weeks or more and sometimes continuing for years.
Hives affect people of all ages, races, and genders. However, some individuals—like those with allergies or autoimmune diseases—are more likely to get them. Welts commonly show up on the trunk, arms, legs, and face, but they can appear anywhere on the body. In severe cases, hives may also occur inside the mouth or throat. Episodes can last just a few hours or persist throughout the day, with new kinds of this condition appearing as older ones fade.
The redness and swelling of hives happen because the body releases histamine and other chemicals into the skin. These chemicals cause blood vessels to widen and leak fluid, producing the classic red, raised bumps. Often, the exact cause of hives is unknown, which can be frustrating for both patients and doctors. Still, knowing the different types of hives and how they work is key to effective treatment and prevention.
There are two main types of hives: acute and chronic. Acute hives come on suddenly and usually go away within six weeks. They are often triggered by food allergies, medications, insect stings, or infections. Chronic hives last longer than six weeks and may have no obvious cause. Sometimes, chronic hives are autoimmune, meaning the immune system mistakenly attacks healthy skin cells.
Another type is physical urticaria, where physical triggers like pressure, cold, heat, sun exposure, water, or exercise cause outbreaks. Each type has a different cause, so correctly identifying the subtype is important for treatment. Also, angioedema—which is deeper swelling under the skin—often happens with hives. This can affect the eyes, lips, or throat and may cause breathing problems.
While hives usually aren’t life-threatening, they can signal a serious allergic reaction called anaphylaxis, especially if symptoms include trouble breathing, dizziness, or throat swelling. These cases need emergency medical care. Otherwise, antihistamines are the first treatment choice. Additional treatments depend on how long and how often the hives appear, and what causes them.
In the following sections, we will discuss the causes of hives, the key symptoms to watch for, how hives are diagnosed, treatment options, possible complications, and the outlook for people with this often unpredictable skin condition. Understanding these topics can help patients and caregivers better manage hives and improve quality of life.
