Aquagenic urticaria: diagnostic and management challenges

Aquagenic urticaria (AU) is a rare inducible form of physical urticaria, which occurs in response to cutaneous exposure to water, including sweat and tears. Patients present with characteristic 1-3 mm folliculocentric wheals with surrounding 1-3 cm erythematous flares within 20-30 minutes following skin contact with water. In rare cases, there are concomitant systemic symptoms, such as wheezing or shortness of breath. The pathogenesis of AU is poorly understood at this time, and it appears to be mediated in both a histamine-dependent and independent manner. Diagnosis is based on eliciting a thorough clinical history combined with a water challenge test. Some patients may need to undergo further testing to exclude other physical urticarias. Rarely, multiple physical urticarias can be present in one patient, which can complicate diagnosis and treatment. Currently, the first-line therapy for AU is an oral administration of nonsedating, second-generation H₁ antihistamines, but many patients may require further interventions to have adequate symptomatic control. In this review, we discuss the diagnostic and management challenges of AU. We review the key diagnostic features that differentiate AU from other physical urticarias. We additionally describe a therapeutic ladder for the treatment of AU and the rationale supporting these treatments.