A Systematic Review of Aquagenic Urticaria - Subgroups and Treatment Options

Background: Aquagenic urticaria (AquaU) is a rare variant of chronic inducible urticaria where wheals occur after skin contact with water. Information on clinical manifestations and treatment outcomes is limited, which makes the management of AquaU challenging. Objective: To systematically review disease features and relevant triggers of AquaU and patients’ response to treatment. Methods: Related articles were searched by use of the terms “aquagenic urticaria” and “aquagenic angioedema” until June 2021 and reviewed according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis recommendations. Results: A total of 77 patients with AquaU were investigated in 59 studies including 47 case reports and 12 case series. AquaU predominantly presented in women (47 patients, 61%), and the mean age of onset of the disease was 19.6 ± 10.8 years (range: 0-54 years). Wheals commonly occurred in localized areas and regardless of the water temperature. Based on the reviewed evidence, AquaU can be classified as familial AquaU (FAquaU, 18.2%) and acquired AquaU (AAquaU, 81.8%). Although many treatments were used in both subtypes of AquaU, the use of second-generation H1 antihistamines (2ndAH1) was reported most often to achieve marked improvement in both subtypes. The use of topical therapies in AquaU, which most commonly use hydrophobic vehicles, is poorly documented and of controversial efficiency. Conclusions: AquaU is proposed to be classified into 2 subtypes, FAquaU and the more common AAquaU. Treatment with a 2ndAH1 is recommended as the first-line treatment for both types of AquaU. Further studies are required to fill knowledge gaps.