Hives, medically known as urticaria, are a common skin reaction characterized by itchy welts. These raised bumps appear when the body releases histamine, a chemical that causes small blood vessels to leak fluid into the skin. Hives are not contagious and do not spread from person to person. Their appearance indicates an internal response rather than a transmissible infection. While the rash can spread across an individual’s body, it cannot be caught by someone else. The underlying triggers for hives are diverse, ranging from environmental factors to internal bodily reactions.
Understanding What Triggers Hives
Hives develop from various internal and external factors. The body’s immune system releases histamine in response to perceived threats or stimuli, leading to the characteristic skin reaction.
Allergic reactions are a frequent cause. Common allergens include specific foods like peanuts, eggs, nuts, shellfish, and milk, as well as certain medications such as antibiotics (especially penicillin and sulfa drugs), aspirin, and ibuprofen. Insect stings or bites, pet dander, pollen, and latex can also prompt this immune system reaction.
Physical stimuli can also induce hives, a condition known as physical urticaria. Pressure on the skin, such as from tight clothing, can cause these welts. Extreme temperatures, both hot and cold, sunlight exposure, and even exercise or sweating can trigger a histamine release.
Infections, both viral and bacterial, are another common cause of hives, particularly in children. Examples include the common cold, infectious mononucleosis, hepatitis, strep throat, and urinary tract infections.
Stress and anxiety can also be triggers for hives, sometimes referred to as stress urticaria. High levels of tension can cause the body to release histamine, leading to an outbreak.
Identifying Hives and When to Get Help
Hives appear as red or skin-colored, raised, itchy welts, also known as wheals. These welts can vary in size and shape, ranging from small bumps to large patches, and can appear anywhere on the body. When pressed, the center of a red hive will temporarily turn white, a phenomenon called blanching.
The rash can be localized to one area or spread across the body, often feeling itchy, stinging, or burning. Individual hives are transient, frequently changing shape, moving around, disappearing, and reappearing within hours. Most cases of hives resolve on their own within 24 to 48 hours, though some can persist for days or weeks.
Medical attention is necessary if hives are accompanied by more severe symptoms, which could indicate a serious allergic reaction called anaphylaxis. Seek immediate help for swelling around the eyes, cheeks, lips, inside the mouth, or in the throat. Difficulty breathing, wheezing, dizziness, hoarseness, severe coughing, difficulty swallowing, or slurred speech warrant emergency medical care.
You should also consult a healthcare professional if hives are persistent, lasting longer than a few days, or if they recur frequently over time. While most hives are harmless, a doctor can help identify underlying causes and recommend appropriate management or treatment options, such as antihistamines, or conduct further tests if needed.