Aquagenic urticaria (also known as water allergy) is a rare allergic reaction in the form of urticaria that develops soon after the skin contacts with the water.
It is a rare condition, a form of physical urticaria which usually affects women and occurs for the first time at the age of puberty. On the areas of the skin that came into contact with the water appear the pruritic follicular wheals. This kind of allergy is not connected with the temperature of the water or salts which it contains – people who suffer from aquagenic urticaria develop the same reaction with distilled water as well. The cases of aquagenic urticaria are mainly sporadic; also some family histories of the condition were reported.
Causes of aquagenic urticaria
There is no concrete data on the causes of the condition. There are several theories of the disease’s origin: 1) allergic theory – the symptoms of the urticaria are caused by the immune response (degranulation of the mast cells with the realization of histamine) triggered by the chemical substance dissolved in the water; 2) toxic theory – toxic elements present in the water lead to the occurrence of the hives. Some of the scientists suggest that a toxic can be produced during an interaction between the water and epidermis (the outer layer of the skin).
Urticaria usually affects women and is rare among men. For the first time the symptoms occur when a girl is at the age of puberty. The risk factors include the allergic reactions in the past, family history of allergic conditions etc.
It was reported that people who suffer from familial lactose intolerance – it be associated with the gene loci and that is a carrier of such disorder (Chromosome 2q21) and is responsible for the production of lactase enzyme that helps to digest lactose. Those females who have Bernard-Soulier syndrome or a sibling with such condition (mutation on Chromosome 3) are also known to develop aquagenic urticaria easily.
Symptoms of aquagenic urticaria can occur after bathing, swimming, or walking in the rain. In 15 minutes after the exposure erythema (redness) or hives appear on the skin. The hives are small (approximately 1–3 mm), red- or skin-colored welts (called wheals) with defined edges. The rash typically develops on the neck, upper trunk and arms, but it can occur anywhere on the body. The affected skin itches intensively, within the proceeding hours these lesions could become painful and even blister. Wheals generally disappear within 30 to 60 minutes, although sometimes the hives remain for hours after the exposure. In extreme cases it may become difficult to swallow or even breathe.
The diagnosis of aquagenic urticaria becomes obvious by the estimation of the clinical history of the patient. The doctor may administrate the water test during which the distilled water would be applied on the part of the skin (usually it is application of a 35℃ water compress to the upper body for 30 minute). Aquagenic urticaria is known to be accompanied by the other forms of urticaria that’s why other tests may be conducted to rule out other allergic reactions such as a pressure test, exercise test, and ice-cube test.
The condition should be distinguished from aquagenic pruritus, in which brief contact with water evokes intense itching without wheals or flushing.
There is no effective treatment for the condition, although some medications are known to lessen the symptoms of the disease and comfort affected people.
- Oral antihistamines (hydrochloride, terfenadine, cyproheptadine) may be used, although the response may vary from person to person;
- Topical corticosteroids;
- Phototherapy – Ultraviolet B (UVB) light treatments , such therapy thickens the epidermis and avoids the contact of water with the other tissues of the skin;
- PUVA-therapy – is an ultraviolet light therapy treatment using the sensitizing effects of the drug psoralen;
- Stanozolol (an anabolic steroid);
- Creams as a barrier between water and the skin – an oil in water solution or emulsion cream can be applied to the skin to protect it from water exposure;
- A low dose of a selective serotonin reuptake inhibitor, in combination with cyproheptadine and methscopolamine;
- Bath with sodium bicarbonate (0.1–0.5 kg/bath).