Hives, also known as urticaria, are raised red bumps or splotches on the skin that are usually caused by an allergic reaction to something in the environment or something that was eaten. However, hives can also be caused by other factors such as stress, tight clothes, exercise, illnesses, infections, excessive exposure to hot or cold temperatures, or irritation due to excessive sweating. The actual cause of hives may not be identifiable in some cases.

Some of the most common causes of hives include:

• Foods (such as nuts, milk, eggs, shellfish, and others)
• Medications (such as antibiotics, aspirin, and ibuprofen)
• Insect bites or stings
• Physical triggers (such as pressure, cold, heat, or vibration)
• Emotional stress
• Infections (such as strep throat, urinary tract infections, and others)
• Environmental factors (such as pollen, dust mites, chemicals, and others)
• Scratching or pressing on the skin (such as wearing itchy or tight clothing)
• Problems with the immune system

Hives are usually not life-threatening, but any swelling in the throat or any other symptom that restricts breathing requires immediate emergency care. Treatment for hives may include antihistamines or steroids. If you develop hives, it is important to try to identify the cause to avoid them in the future.