Aquagenic Urticaria (Physical Urticarias)

Physical urticaria refers to a class of chronic urticaria, a hive or wheel type reaction, to a physical stimulus. The literature seems to indicate that for some patients the specific physical trigger results in hives, but in others the stimulus is the only common factor in the otherwise idiopathic condition. A large group of physical stimuli have been characterised and used as diagnostic criteria (1), which include: dermographism, delayed pressure urticarias/ angioedema, cholinergic urticaria, local heat induced urticaria, exercise induced urticaria, solar urticaria, vibrational angioedema, and aquagenic urticaria.

Though fewer than 50 cases of aquagenic urticaria have been documented in medical journals, relatively recent online tabloids and blogs have written articles about the condition (2,3). The clinical features of the condition include small perifollicular wheels on any skin region after contact with water (distilled, tap, or saline). For some patients characteristics of the water effected the condition, salinity, pH, and others factors (4,5). Many patients suffering from aquagenic urticaria have also been diagnosed with cholinergic urticaria or dermographism (6,7).

From the known mechanism of the immune system we have learned about this year it seems unlikely that water itself could be recognized by the immune system. However, a few hypothesis for the mechanism of the condition have been proposed. It is possible that the water acts to carry an antigen (possibly sebum) through from the epidermis to the dermis where it is recognized by mast cells causing the localized reaction (8). Further studies with this hypothesis demonstrated that organic solvents increased sensitivity to the reaction, and removal of the stratum corneum layer of the skin produced similar results. Another theory suggested cholinergic activation resulted in the reaction, scopolamine was shown to decrease reactions in two patients, but pre-treatment with atropine did not suppress reactions. The injection of methacholine, which usually elucidates cholinergic reactions for diagnostics was negative when tested on aquagenic urticaria patients (9). It may also be possible that the activation or involvement of the sensory neurons, perhaps presenting antigens from a latent virus could provide a possible mechanism, though no research has been done in this vein. Similarly, it is possible that ions in the water change an already present molecule of self into a recognizable antigen.

Elucidating a mechanism, or further understanding of aquagenic urticaria and other types of physical urticaria may provide immunologists new insights into antigen presentation, and inflammation.


1. Kontou-Fili, K, Borici-Mazi, R, Kapp, A, et al. Physical urticaria: classification and diagnostic guidelines. An EAACI position paper. Allergy 1997; 52:504.
2. http://www.dailymail.co.uk/news/article-520329/The-teenage-girl-allergic-WATER.html
3. http://abcnews.go.com/Health/AllergiesNews/story?id=7401149&page=2
4. Gallo, R, Cacciapuoti, M, Cozzani, E, Guarrera, M. Localized aquagenic urticaria dependent on saline concentration. Contact Dermatitis 2001; 44:110
5. Tkach, JR. Aquagenic urticaria. Cutis 1981; 28:454
6. Parker RK, Crowe MJ, Guin JD. Aquagenic urticaria. Cutis. 1992 Oct;50(4):283-4
7. Luong KV; Nguyen LT. Aquagenic urticaria: report of a case and review of the literature. Ann Allergy Asthma Immunol. 1998 Jun;80(6):483-5.
8. SHELLEY, WB, RAWNSLEY, HM. AQUAGENIC URTICARIA. CONTACT SENSITIVITY REACTION TO WATER. JAMA 1964; 189:895
9. utdol.com