UNDERSTANDING AQUAGENIC URTICARIA (WATER ALLERGY): SYMPTOMS, CAUSES AND MANAGEMENT
Medically Reviewed by Dr. Rosmy Barrios
Aquagenic urticaria is a rare condition of an allergic reaction to water, sometimes referred to informally as “water allergy”. While it may seem unbelievable, this condition is real and can cause discomfort and distress to those who suffer from it.
This article closely examines aquagenic urticaria, exploring its prevalence, symptoms, triggers, diagnosis, and treatment options.
What is Aquagenic Urticaria?
Aquagenic urticaria (AU) is possibly the rarest form of physical urticaria, commonly known as hives. Hives refer to a skin rash that forms welts, swells, itches, and bleeds.
AU is a severe condition primarily triggered by contact with water, irrespective of the temperature or source.
How Common is Aquagenic Urticaria?
Aquagenic urticaria is a sporadic condition, with roughly 100 cases documented worldwide.[1] It is more commonly seen in women than men and typically develops during puberty or early adulthood.
Is Aquagenic Urticaria Contagious?
No, aquagenic urticaria is not contagious. It is a physical condition triggered by contact with water and cannot be passed from person to person.
How is Aquagenic Urticaria Different from Other Water-Related Conditions?
It is important to note that aquagenic urticaria differs from other water-related conditions, such as water intoxication, swimmer's itch, or irritant contact dermatitis.
Water intoxication is a potentially life-threatening condition that occurs when a person drinks too much water in a short period.[2] Swimmer's itch is a water parasite-induced skin rash that creates an allergic reaction,[3] while irritant contact dermatitis is a skin irritation caused by a variety of triggers, including frequent exposure to water that strips the skin of its protective barrier.[4]
One key difference between AU and these water-related disorders is that those with AU cannot make frequent contact with water without risking symptoms, whereas those with the above conditions can and do so on a very frequent basis.
Symptoms
The main symptom of aquagenic urticaria is the development of hives or welts on the skin within 20-30 minutes of contact with water. Allergic symptoms tend to subside within 30-60 minutes after water exposure ceases.[5]
Hives in AU can appear in any body area and may vary in size and shape. They can burn or sting, and appear red.
In addition to hives, some people with AU may also experience aquagenic pruritus, a severe itching sensation after contact with water. This can be highly uncomfortable and may lead to scratching, further irritating the skin.
Less commonly, people may also experience skin lesions, wheezing, difficulty swallowing, and shortness of breath.
This condition is very stressful over and above the physical symptoms, as contact with water is unavoidable. Some people with the condition resort to drinking milk and frequently visiting the hospital due to dehydration.
What Causes Water Allergy?
The cause of AU is still unknown. In ordinary allergic reactions,[6] hives respond to histamine and similar compounds released by mast cells and basophils in the skin. These substances induce blood vessel dilation and rapid swelling, leading to urticaria. This process occurs in some people with AU,[7] yet not all.
Several proposed theories exist on how water can trigger an allergic reaction. Scientists have suggested as early as the 1960s that the condition is caused by:[8]
- Water reacting with sebum to form a toxic substance, leading to histamine release.
- Osmotic pressure changes around hair follicles that lead to excess water diffusion, indirectly triggering urticaria through rapid fluid displacement.
- Water-soluble antigens in the epidermis dissolve and diffuse, thereby releasing histamine.
Since there are very few reported cases worldwide to date, the condition is very difficult to study.
Researchers have identified two types of AU: familial (inherited) and acquired (sporadic). One review suggests a higher prevalence of the familial type in those affected, suggesting that it may have genetic origins.[9] However, it is important to note that research is limited, and no definitive genetic cause has been confirmed.
In conventional hives, many underlying mechanisms can contribute,[10] suggesting that AU can have complex multi-factorial causes that lead back to autoimmune disease, genetic disorders, immune and nervous system dysfunction, infections, and problems with coagulation (blood clotting) pathways.
A few cases of AU may share a link with severe light sensitivity[11] (Familial polymorphous light eruption) and HIV infection.[12]
Aquagenic Urticaria Triggers
The main trigger for aquagenic urticaria is contact with water, regardless of its temperature or source. This means that those with the condition can react to all types of water, including rain, seawater, tears, and sweat.
In addition to water, some other triggers may worsen symptoms of aquagenic urticaria as they generate water or exacerbate dehydration. These include:
- Heat and humidity
- Exercise
- Emotional stress
- Certain medications
- Hormonal changes
Can Stress or Anxiety Trigger Aquagenic Urticaria?
Stress and anxiety are known to intensify allergic symptoms in some people and increase their vulnerability due to the way they interact with the nervous and immune systems.
Can I Drink Water if I Have Aquagenic Urticaria?
Whether those with AU can drink water or not depends on the severity of their condition. Some individuals find drinking water causes irritation in their throat and digestive system or their lips to swell. Instead, milk rich in calcium and magnesium may help these individuals attain optimal hydration levels. However, while rare, some individuals may have a familial susceptibility to lactose intolerance in addition to AU.[13]
It is important to note that switching to milk may not be essential (or effective) for all people with AU and should be done under medical supervision due to the potential risk of dehydration.
Others may drink water without symptoms if they take antihistamine medication daily.
It is important to note that switching to milk may not be essential (or effective) for all people with AU and should be done under medical supervision due to the potential risk of dehydration.
Others may drink water without symptoms if they take antihistamine medication daily.
How Can I Shower or Bathe with Aquagenic Urticaria?
Showering or bathing can be challenging for people with aquagenic urticaria, as it involves direct contact with water. However, some tips may help make this process more manageable:
- Use lukewarm water instead of hot or cold water
- Keep showers short and avoid soaking in the bath for long periods
- Use a gentle, fragrance-free soap
- Pat your skin dry. Rubbing it with a towel may exacerbate symptoms
- Apply a moisturizer after showering to help soothe theskin
Diagnosis of Aquagenic Urticaria
If you suspect that you may have aquagenic urticaria, it is vital to consult an experienced healthcare practitioner for an accurate diagnosis. Your doctor will conduct a medical evaluation, ask about your symptoms, and build a clear picture of your medical history.
In some cases, your doctor may also perform a water challenge test, where a damp cloth is applied to the skin for 20-30 minutes to see if it triggers a reaction. This test can help confirm the presence of aquagenic urticaria.[14]
Treatment and Management of Aquagenic Urticaria
Unfortunately, aquagenic urticaria has no cure. However, some treatment options can help manage symptoms and improve quality of life.
- Antihistamines are a standard treatment for hives and can effectively reduce the itching and swelling caused by aquagenic urticaria. They work by blocking the release of histamine, a chemical released during an allergic reaction. Second-generation H1 antihistamines can be taken daily with minimal side effects, such as daytime drowsiness.[15]
- Topical steroids, such as hydrocortisone cream, may help reduce inflammation and itching caused by hives. However, research about their efficacy for treating water allergy is limited, and they may not provide optimal relief, especially if they contain water. Oral steroid therapy helped improve AU in a person with HIV.
Other sources suggest that sunbathing for 5-15 minutes a day can enhance the thickness of the skin, potentially lowering water penetration.[16] Other studies reveal that phototherapy did not improve symptoms of AU after a year.[17]
Those with the condition ought to monitor their health and get frequent checkups to ensure they remain adequately hydrated and do not develop kidney problems.
Latest Advancements in Treating Aquagenic Urticaria
In recent years, there have been some advancements in the treatment of aquagenic urticaria. One promising treatment is omalizumab,[18] a medication typically used to treat asthma and allergic rhinitis by binding to free IgE. It was recently approved to treat food allergies. This medication is effective in reducing symptoms of aquagenic urticaria in some. Two older patients treated with two doses of omalizumab experienced complete remission from their water allergy within six months.[19] It is to be noted that while the treatment has shown potential, it is not yet confirmed as effective due to the limited sample size.
Conclusion
Aquagenic urticaria is a rare condition that causes an allergic reaction to water. Treatment options can effectively manage symptoms, allowing people with the condition to manage some water exposure and improve their quality of life. If you suspect you may have aquagenic urticaria, find a specialist who can provide an accurate diagnosis and discuss the best treatment plan. People with AU can still lead happy and fulfilling lives with proper management.
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