There is a similar condition, called angioedema, in which the swelling is below the surface of the skin, forming large, thick, firm welts. They may be accompanied by swollen eyes and mouth, swelling of the hands, feet, and throat, difficulty breathing, stomach cramping, and chemosis, swelling of the lining of the eyes. The affected areas may be painful and feel warm to the touch. It can be life-threatening and requires emergency medical attention.
There are two types of hives: acute, which are present for six weeks or less, and chronic, lasting six weeks or longer. The causes are very different.
Hives, both acute and chronic, are treated with antihistamines, oral and topical. Less commonly, oral corticosteroids may be used for more severe, persistent cases. Recurrent cases may be evaluated by an allergist. The most effective management is to identify what triggered the hives, then avoid or eliminate the trigger(s). In most chronic cases, the triggers cannot be identified.
Acute urticaria has virtually countless causes, including:
- Allergies to foods, especially peanuts, eggs, nuts, and shellfish
- Insect stings or bites
- Medications, such as aspirin and antibiotics (sulfa, penicillin)
- Heat, and/or cold
- Infections, including the common cold, urinary tract infection, strep throat, infectious mononucleosis, hepatitis, and other viral infections
- Allergens which are present as particles in the air or that touch your skin
The cause of chronic urticaria often cannot be identified. It is thought to be related to a persons own immune system about 50% of the time. These cases are called idiopathic urticaria. Some types of chronic urticaria are associated with:
- Changes in temperature
- Emotional stress
- Alcoholic drinks
- Menstrual periods
- Pressure hives people sitting on their buttocks all day, or wearing a belt too tightly.
- Sun exposure