Hives, also known as urticaria, are itchy, raised welts that are found on the skin. They can be caused by an allergic reaction to something in your environment or something you ate, or they may sometimes happen because of an underlying health issue. Hives can appear anywhere on the body and may change shape, move around, disappear and reappear over short periods of time. They can be red or skin-colored "wheals" with clear edges and usually appear suddenly and go away just as quickly. The most noticeable symptom of hives is the welts that appear on the skin. Welts may be red but can also be the same color as your skin. They can be small and round, ring-shaped, or large and of random shape. Hives are itchy, and they tend to appear in batches on the affected part of the body. They can grow larger, change shape, and spread. Hives may disappear or reappear over the course of the outbreak. Individual hives welts can last anywhere from minutes to months – or even years.

Hives can be triggered by a variety of factors, including:

• Allergens, such as food, medications, pollen, pet dander, latex, and insect stings
• Environmental factors, such as heat, cold, sunlight, vibration, pressure on the skin, and exposure to chemicals
• Emotional stress
• Medical conditions, such as thyroid disease, infection, allergy, and cancer
• Physical factors, such as exercise, tight clothing, and excessive sweating

Treatment for hives may include antihistamines or steroids. If you experience hives, it is important to try to identify the trigger and avoid it in the future.