Aquagenic Urticaria aka Water Allergy

A Rare Medical Condition Known As Water Allergy

Woman taking a shower
Aquagenic urticaria or water allergy is a true reaction to water. What do you need to know about this rare condition?. Greg Kessler/Photolibrary/Getty Images

What is Water Urticaria (Aquagenic Urticaria)?

Water urticaria, also known as aquagenic urticaria (AU) or water allergy, is a rare medical condition in which hives develop rapidly on the skin as a result of contact with water (physical urticaria.)

Water urticaria may occur regardless of the source of water, it doesn't matter if the water is hot or cold, or if it has been chemically treated.

When Does Water Allergy Occur?

Since water urticaria may occur during any activity in which water comes in contact with your skin, this allergy can occur with bathing, swimming, or going out side in rainy weather.

Some patients with water urticaria experience a reaction if they come in contact with the water they drink.

In addition to external water sources, hives may occur in response to sweat and tears.

More women than men are affected with this condition which starts around the onset of puberty. Because the condition is so rare, there is no clear understanding of the cause or the effectiveness of treatment.

What is Physical Urticaria?

Water is only one of the physical factors that can lead to hives, and it's thought that six to 17 percent of hives classify as "physical urticaria." In addition to water, hives have been known to occur in response to cold, pressure, vibration, sunlight, exercise, changes in temperature, and heat. It appears that there is a distinct subtype of aquagenic urticaria in which hives only occur in response to salt water.

Symptoms of Water Urticaria

The hives (urticaria) that are associated with water urticaria are rather small and usually develop on your neck, upper trunk and arms, but can appear anywhere on your body.

Similar to other forms of urticaria, symptoms of water urticaria include:

  • Itching
  • Burning sensation
  • Elevated patches of skin (hives) - The hives are usually small, as noted, only 1 to 3 millimeters in diameter surrounded by a 1 to 3 centimeter diameter of redness (the flare)
  • Skin that has become flushed
  • Sometimes the hives are combined with body wide (systemic) symptoms such as wheezing or shortness of breath

After exposure to a substance that contains water, symptoms should appear quickly (within 30 minutes). After your skin is no longer in contact with water, symptoms should subside within 30 to 60 minutes.

Diagnosis of Water Urticaria

Water urticaria is generally diagnosed by your family doctor or internist who will refer you to dermatologist or allergist to confirm your condition. After taking a complete medical history, your doctor will most likely perform a “water challenge test” where water will be placed on your skin to see if there is a reaction.

Your doctor will perform a careful exam and blood tests to rule out other conditions or diseases. Some people may develop hives for a number of different reasons which can ;make the diagnosis more difficult.

Underlying Cause - Pathophysiology

It's not certain exactly what the mechanism is which causes water allergy. It appears that part of the response is related to the release of histamine (as with nasal allergies, for example) but there are other mechanisms at work as well.

There may be a genetic aspect to the condition, and in some cases it has been found to run in families.

Treatment of Water Urticaria

There is no cure for water urticaria but there are some treatments that may provide you with relief. Some of the treatments include:

Medications - While first generation antihistamines such as Vistaril (hydroxyzine) and  Benadryl (diphenhydramine) may be helpful, they can be very sedating. The treatment of choice, therefore, is second generation antihistamines such as Zyrtec (cetirizine) and Xyzal (levocetirizine) which are less likely to be sedating. That said, these medications alone are usually not effective enough to control all of the symptoms.

The medication Xolair (omalizumab) used for asthma has also been found to be effective for some people.

Other treatments - There is evidence that using a petrolium-containing cream as a barrier between your skin and water may be effective when symptoms are not controlled by antihistamine therapy. Other treatments which have been tried include phototherapy, anabolic steroids, bathing in sodium bicarbonate solutions, and beta blockers.

You and your doctor will have to try various treatment plans to find the right one for you.  In addition to the above treatments, there are currently clinical trials (medical research studies) in progress investigating newer and better treatments.

Support for People with Aquagenic Urticaria

There are support groups, Facebook groups, and a free national research registry dedicated to rare medical disorders. Many studies are looking for people with specific illnesses to help researchers come up with more effective treatments.


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Gallo, R., Goncalo, M., Cinotti, E., Cecchi, F., and A. Parodi. Localized Salt-Dependent Aquagenic Urticaria: A Subtype of Aquagenic Urticaria?. Clinical and Experimental Dermatology. 2013. 38(7):754-7.

Rorie, A., and S. Gierer. A Case of Aquagenic Urticaria Successfully Treated with Omalizumab. Journal of Allergy and Clinical Immunology in Practice. 2016. 4(3):547-8.

Rothbaum, R., and J. McGee. Aquagenic Urticaria: Diagnostic and Management Challenges. Journal of Asthma and Allergy. 2016. 9:209-213.