Alcohol-Induced Hypersensitivity: A Clinical and Mechanistic Overview.

Patients with reactions to alcohol pose a diagnostic challenge for allergists, since such symptoms can represent true hypersensitivity, alcohol as a cofactor for other allergens, or entirely separate mimicking conditions. The literature on this topic is limited, with much of the current understanding drawn from case reports, small case series, and mechanistic studies rather than large scale trials. Although the underlying mechanism is not fully understood, several pathways have been proposed to explain this cofactor effect, which this review will discuss in detail. Alcohol has also been identified as a direct trigger of IgE-mediated, non-IgE-mediated, and delayed hypersensitivity reactions, and can exacerbate pre-existing atopic and mast cell-related conditions, including aspirin-exacerbated disease, mastocytosis and urticaria. This review provides a comprehensive overview of these mechanisms and the clinical spectrum of alcohol-related reactions, highlights key mimickers relevant to the allergist, and provides a practical framework for diagnostic evaluation.