Allergic to Water?

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Q: My eldest son, who is 15, seems to be allergic to water. This has just come on within the last year. When he takes a shower his chest itches really badly. He also gets this way when he swims. We took him to the dermatologist’s office and saw a physician’s assistant who said it just must be the soap, and to change the soap and things will be fine. It’s been frustrating for him; it isn’t the soap or laundry detergent because my family is a sensitive family and we use All Free and Clear for the laundry and Dove sensitive skin soap. I happen to have cold urticaria (a form of hives that’s caused by cold exposure). Do you have any idea what this might be? Could this be a form of cold urticaria? Do you know what we can do for him?

A: There are some clues in your question that may help lead to a diagnosis. The first is that your son’s itching occurs in the shower and when he goes swimming. This leads me to think it is not the soap or laundry detergent. The next hint is that it only happens after exposure to water and is not reactive to changes in air temperature. Given this information, I suspect your son may have a rare condition known as aquagenic pruritis, not cold urticaria. There are some similarities between the two, but they are really very different.

Aquagenic pruritis is a condition that results after exposure to water of any temperature. Symptoms develop within minutes and may include itching, burning or even a prickly sensation. Most times there are no skin changes, although a faint, bumpy, itchy red rash may occur. The symptoms last from 10 minutes to several hours, and usually are experienced on one or more of the following skin surfaces: Chest, back, arms or legs. While the exact cause of this condition is uncertain, some investigators suggest it is a result of extreme skin sensitivity (but not allergy) to an added ingredient (chlorine, fluoride, others) or mineral present in the water.

Regarding treatment, use of capsaicin cream applied two to three times per day has provided many individuals with effective relief. Other medical options include ultraviolet B phototherapy, leukotriene-receptor antagonists (requires a prescription), antihistamines and beta-blockers (medications used for cardiovascular disease).

While cold urticaria also produces itching in affected individuals, it differs in that it often causes redness, pain and swelling of the unprotected skin after exposure to cold air or water. Even holding a cold drink may lead to swelling of that particular hand. In fact, we often diagnose this condition by applying an ice cube against the skin of the forearm for three to five minutes. In unaffected individuals this would cause redness, but in those with cold urticaria a red, itchy and swollen area may appear within minutes after removal of the ice cube.

The most common type of cold urticaria is by contact with the cold substance. However, there are additional conditions (paroxysmal cold hemoglobinuria, familial cold urticaria, others) that can result in similar, or even life threatening (irregular heartbeat, drop in blood pressure) reactions. This makes it especially important to undergo a thorough evaluation by a physician skilled in the diagnosis and treatment of these conditions.

I also need to mention the blood disorder known as polycythemia vera. While it is rare in people under the age of 40, it can lead to itching within 15 to 30 minutes after exposure to water, especially when it’s warm.

Because your son’s condition is rare and difficult to diagnose, I would strongly encourage a visit with a pediatrician, pediatric dermatologist and/or pediatric allergist/immunologist.

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Robert Danoff, D.O., M.S., is a family physician and program director of The Family Practice Residency, as well as the combined Family Practice/Emergency Medicine Residency programs at Frankford Hospitals, Jefferson Health System, Philadelphia, Pa. He is the medical correspondent for CN8, The Comcast Network, a regular contributor to Discovery Health Online and a contributing writer to The New York Times Special Features. (Read his full bio.)