What causes hives (urticaria)?

October 28, 2003

What causes hives (urticaria)? Finding the source is sometimes difficult. Cold urticaria is one of the physical urticarias, and is caused by exposure to cold temperatures. But what prompts the body to respond to cold temperatures with an itchy rash?

Cold urticaria may not be as rare as you think. According to the American Academy of Allergy, Asthma & Immunology, 25% of the population will experience urticaria (hives) at least once in their lives. For about half of these people, the hives will last less than six weeks. The remaining 50% will develop chronic urticaria (urticaria lasting longer than six weeks.)

Estimates of the incidence of cold urticaria vary according to source. In one study, 2% of patients with chronic urticaria had cold urticaria. Another source reports that the physical urticarias (urticaria caused by stroking or pressure to the skin, exercise, cold, heat, sunlight, or skin contact with water) together comprise 15% of chronic urticaria.

The physical urticarias listed above are not IgE mediated. This means they are not a true allergic response. Urticaria caused by food, some drugs such as antibiotics, stinging insects, and skin contact with some agents such as latex is an IgE mediated (allergic) response. Urticaria produced by cold and other physical causes, aspirin and some other drugs, as well as contact urticaria caused by irritants is not a true allergic response.

Urticaria is not contageous. While a tendency to IgE mediated allergic responses does run in families, this is more commonly associated with the allergic triad of rhinitis, asthma, and eczema. It is not usually associated with the physical urticarias such as cold urticaria.

However, there is a rare condition called familial cold urticaria that is inherited. Familial cold urticaria is not a true urticaria. Patients with this condition experience a burning rash described as painful rather than itchy. This rash occurs 30 to 45 minutes after exposure to cold, and is accompanied by joint and muscle pain, thirst, fever and chills and headaches. Symptoms can last 48 hours.

Endocrine (hormonal) changes such as thyroid disease, pregnancy, menopause, and diabetes can precipitate urticaria.

Urticaria or conditions that resemble urticaria can be caused by lupus, hepatitis, infectious diseases, viral diseases, cryoglobulinemia (abnormal proteins in the blood), mastocytosis (too many mast cells in the body), autoimmune diseases, urticarial vasculitis, rheumatoid diseases, mononucleosis, scabies, and syphilis.

While syphilis can cause cold urticaria, having cold urticaria does not mean you have syphilis. The pap smear diagnoses abnormal cells that can lead to cancer. A negative pap smear does not mean you do not have syphilis. In the early stages of syphilis, there may be no physical symptoms evident to the person doing the pap smear. Your physician can do a blood test to check for syphilis.

If the urticaria is accompanied by swelling around your face or throat, or if you experience trouble breathing, you should seek emergency medical care immediately. If the urticaria lasts longer than 24 hours, it may be a sympom of a more serious condition, and you should contact your physician. Your physician is the one most qualified to advise you on treatment measures, what to avoid, and how to manage your urticaria.

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