Hives (Urticaria)

Home » Skin Conditions » Hives (Urticaria)

Urticaria (hives)

Urticaria, also known as hives, is a common allergic reaction that shows up as red, often itchy, welts. These wheals can vary in size and location and last from minutes to weeks or more. Common triggers are foods or drugs that a person is allergic to.

Hives are produced by blood plasma leaking through tiny gaps between the cells lining small blood vessels in the skin. Histamine is a chemical released from cells in the skin called “mast cells,” which lie along blood vessels. When hives form around the eyes, lips or genitals, the tissue may swell excessively. Although frightening, the swelling usually goes away in less than 24 hours. Severe cases of hives may cause difficulty in breathing or swallowing and emergency room care is required.

Acute Urticaria lasts less than six weeks, and often the cause can be easily identified. Common causes are foods, drugs, infections, insect bites, internal diseases, pressure, cold or sunlight.

Chronic urticaria lasts more than six weeks. The cause of chronic urticaria is more difficult to identify and is found only in a small percentage of patients. The dermatologist reviews a patient’s medical history, asks extensive questions, and conducts a thorough physical examination. Testing, such as blood work or a biopsy, may be necessary.

Causes of Urticaria

• Foods: Nuts, chocolate, shellfish, tomatoes, eggs, berries and milk are common foods  that cause urticaria.
• Drugs: Almost any medication — prescription or over-the-counter — can cause hives. It is important to inform the dermatologist of ALL prescription and over-the-counter medications being used to help find the cause of the hives.
• Infections: Many infections can cause urticaria. Viral upper-respiratory tract infections (colds) are a common cause in children. Other viruses, including hepatitis and a number of bacterial and fungal infections, may cause urticaria.
• Physical urticarias may be caused by sunlight, heat, cold, water, pressure, vibration, or exercise. Solar urticaria forms within minutes of sun exposure and typically fades within one to two hours. Cold urticaria appears when the skin is warmed after exposure to cold. Urticaria, which forms in response to the cold or the water when swimming, for example, can produce wheezing, flushing, generalized hives, and fainting.
• Dermatographic Urticaria (Dermatographism) forms after firmly stroking or scratching the skin, and can often occur with other forms of urticaria. It affects about five percent of the population. Most people with this condition are otherwise healthy. Dermatographism may last for months or even years.

Treatment

The best treatment for urticaria is to find and eliminate the cause whenever possible. Antihistamines are prescribed to provide relief and work best if taken on a regular schedule to prevent hives from forming. There are many antihistamines available. No one antihistamine works for everyone. The dermatologist may use combinations to control the urticaria. In severe cases, an injection of epinephrine (adrenalin) may be needed. Cortisone may also bring dramatic relief, but its use must be limited to short periods of time.