Hives are a common allergic condition of the skin. Hives are a symptom of the body's immune system reacting (or over-reacting) to something in the environment or in the body. Unfortunately, what is actually causing the hives is frequently not found.

When hives first appear, reactions to medications or foods are possible causes. Occasionally the hives are a result of the immune system's over-reaction to a recent infection, such as a cold or flu. Hives are rarely due to a reaction to something touching the skin, such as soaps, detergents or lotions, although these can cause different types of allergic skin reactions. These reactions tend to remain on the skin where contact was made, whereas hives come and go rapidly.

If your doctor suspects the cause to be a new medication, the doctor will discontinue the medication. Your doctor will tell you if you can start the medication again or if a substitute medicine is appropriate. Any suspected food should be eliminated from the diet. The most common food triggers are nuts, shellfish and seeds. In children, milk, eggs and soy are common offenders. If no improvement is seen within one week, the food can be re-introduced.

If the hives are present for more than one week, foods are less likely to be a cause, although they can sometimes make the hives worse. If hives are present for more than two months, your doctor may order tests to see if any other medical conditions may be the cause. Conditions in which the immune system attacks itself (auto-immune conditions) are occasionally found. New research suggests that chronic hives may actually be an attack of the immune system on the skin. Again, why this occurs is unclear.

Another reason for chronic hives may be an ongoing infection, especially low-grade infections, such as chronic sinus infections, athlete's foot, bladder infections or vaginal infections. Because of this, any other symptoms that you may have been experiencing should be reported to your doctor.

Once hives have started, they can be aggravated or perpetuated by a number of factors. The most common is scratching itself. Unless this scratching is controlled, it is very unlikely the hives will improve. Other triggers include heat, stress and pressure points, such as the belt or bra areas. Sometimes hives are brought on by "physical" factors, such as cold, sun-exposure, exercise and vibration. Exposure to rubber or latex can occasionally be associated with hives. Inhalants, such as pollens, dust, molds or animal proteins can also be triggers. If this is the case, there are usually nasal/sinus symptoms, too. Hives may be hormone related in women, flaring during different times of the menstrual cycle or during menopause.

In about one-fourth of the cases of chronic hives, foods may play a role in keeping the hives going, although they are rarely the cause. In this situation, food groups can be eliminated from the diet for 7-10 days, and reintroduced at that time. Allergy testing for foods is rarely helpful. Some studies show that food additives or preservatives are more likely to be offenders than the outright food itself. Some common preservatives include BHA/BHT, MSG (monosodium glutamate), yellow, red or blue food dyes, sulfites, parabens or sodium/potassium benzoate.

The treatment of choice for hives is antihistamines, either over-the counter (OTC) or by prescription (Rx). There are a number of antihistamines and they can be used together to control the itching and the hives. These medicines should work immediately, and if one does not work within two days, an alternative medicine should be tried. Occasionally, histamine (H2) blockers will be added to the other antihistamines. These usually take a few days to a few weeks to work.

If the hives are severe you may have swelling. This is called angioedema and is most likely to occur on the face, hands and feet. Sometimes, the facial swelling can be dramatic, especially around the lips and/or eyes. Fortunately, it is very uncommon for the hives to become severe enough to cause breathing or swallowing difficulties. Should this ever occur, however, please contact your doctor immediately.

An evaluation by an allergy specialist is recommended if the hives persist for more than two to three months. Remember, even with this specialist evaluation, the specific cause for the hives is unlikely to be found.

Medications	Notes
Non-sedating antihistamines OTC: Claritin, Alavert, Loratadine RX: Allegra, Zyrtec, Clarinex	Drowsiness is rare Recommended for daytime use
"Classic" antihistamines OTC Diphenhydramine (Benadryl) Chlorpheniramine (Chlortrimeton) Clemastine (Tavist-1) RX: Hydroxyzine (Atarax)	Recommended for nighttime use Can be used in addition to other medications at any time of day
H2 Blockers Cimetidine (Tagamet) Ranitidine (Zantac) Famotidine (Pepcid)	Take several days to several weeks to work Available OTC and by Rx
Cortisone pills or shots	Used in severe cases Not for long term use
Topical products (rubbed onto skin) OTC Cortisone cream Antihistamine cream (Benadryl) Anesthetic cream	Rarely give relief if condition is hives If helpful, suspect a reaction to something touching the skin