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Feedback, In this issue, Issue 7/2026
Is it possible to be allergic to water?
Aug
This year, from June 21 to 27, we celebrated World Allergy Week. This prompted me to find out if it’s possible to be allergic to water. The answer may come as a surprise—it turns out that you can. Although it doesn’t necessarily take the typical form.
The immune system fights—but not always on the right side
Immune systems are complex systems designed to combat various threats—both known and unknown. When the immune system identifies a new factor as dangerous, each time it appears, it triggers defensive processes. When this factor is a substance produced by pathogens (it is not the viruses or bacteria themselves that are recognized by the immune system, but only their antigens, which can vary in each individual case), the situation is the most straightforward and normal. If it is a substance produced by the body’s own cells, the reaction becomes an autoimmune disease. A fairly common scenario, however, is when an inert or nutrient substance is mistaken for a pathogen—in which case the reaction may take the form of an allergy.
It is impossible to predict what the immune system will identify as a threat. Most often, these are markers of viruses, bacteria, or fungi. Certain compounds, such as proteins found in nuts or the venom of hymenopteran insects, trigger allergies more often than others, but this phenomenon can affect any substance. Doctors who use epinephrine to treat the most severe form of allergy—anaphylactic shock—claim that it is the only substance that cannot trigger it. Perhaps this isn’t true, but such a complication would likely manifest during fetal development and probably result in a miscarriage.
Hives and Itching: An Allergy
So how can water—which is ubiquitous in the bodies of all animals, including humans—trigger an allergy? This remains a mystery that medicine has yet to solve. First, the term “water allergy” refers to several sets of symptoms, primarily aquagenic urticaria and aquagenic pruritus. These are skin conditions that appear after contact with an external allergen. Second, this reaction does not usually result in anaphylactic shock—at least not in the cases that have been described. It would likely never occur to anyone to attribute a cause of death to drinking water.
Ultimately, therefore, approximately 100 cases that can be described as allergic reactions to water, manifesting as aquagenic urticaria or aquagenic pruritus, have been reported in the medical literature to date [1]. The first case was reported in 1964 [2]. This is such a small sample size that it is difficult to draw statistical conclusions; however, the condition was found slightly more often (about 60 percent) in women. It often first manifests during puberty. It has been reported only once in identical twins. The condition is more likely to occur when the stratum corneum is thinner, such as after hair removal or contact with solvents.
When Water Is the Allergen
Hives can be triggered by various factors, including heat, cold, or sunlight. Therefore, before identifying water as the cause, it is necessary to rule out more common causes. As a rule, placing a wet gauze pad on the skin is sufficient for diagnosis. However, there have been cases reported where this test did not trigger any symptoms, and the allergic reaction did not appear until after immersion in water. Sometimes, the discomfort was caused by the person’s own tears and sweat.
Symptoms usually appear after 20, sometimes 30 minutes of contact with water. It takes a little longer for them to subside—30–60 minutes. For a condition to be considered hives, redness and a rash must be present. It may be accompanied by other symptoms, such as swelling, and sometimes even a headache, stomachache, or nausea. In some cases, itching replaces the entire set of symptoms.
The mechanism behind the development of allergic symptoms is unknown. Allergists have put forward various hypotheses. One attributes it to changes in osmotic pressure in the hair follicles—due to a certain similarity to the symptoms of folliculitis. Since water circulating in the body does not cause allergies, it is presumed that water itself is not the issue, but rather its role as a carrier of allergens that have previously come into contact with the skin. There are also theories that water reacts chemically with components of sebum, which ultimately triggers allergic reactions.
Some cases were associated only with saltwater, while others were associated only with fresh water. Furthermore, it is not even known what role histamine—the main factor responsible for inflammation and allergic reactions—plays in all of this. According to some studies, histamine levels do not change during the course of symptoms, suggesting that histamine is inactive. On the other hand, antihistamines are often effective in relieving symptoms, and their use is currently considered standard therapy [3], [4].
Thus, water in contact with the skin can trigger allergic symptoms—itching and a rash—but the number of reported cases is still so small that it is difficult to conduct systematic studies, and subsequent, rare cases provide new information about the conditions associated with them. It seems one would have to be exceptionally unlucky to suffer from this condition, although it cannot be ruled out that its prevalence is underestimated.
Main photo: Thượng Hy/Pexels
While writing this article, I used:
[1] Arturo Robles-Tenorio, Victor Manuel Tarango-Martinez, Georgina Sierra-Silva. Aquagenic urticaria: Water, friend, or foe? Clin Case Rep 2020 ;8(11):2121-2124. doi: 10.1002/ccr3.2880
[2] Walter B. Shelley, Howard M. Rawnsley. Aquagenic Urticaria: Contact Sensitivity Reaction to Water. JAMA. 1964;189(12):895–898. doi:10.1001/jama.1964.03070120017003
[3] Robert Rothbaum, Jean S. McGee. “Aquagenic urticaria: diagnostic and management challenges,” J Asthma Allergy. 2016;9:209-213 https://doi.org/10.2147/JAA.S91505
[4] Howard Steinman, Malcolm Greaves. Aquagenic pruritus. Journal of the American Academy of Dermatology, 1985; 13, 91-96
