Scoping review of the effects of antihistamines on physiological responses to alcohol among individuals with natural and induced alcohol flushing reactions.

Individuals with a genetically driven impairment in acetaldehyde metabolism have acute alcohol sensitivity and experience a range of heightened physiological responses, including skin flushing after consuming alcohol. Some individuals consume histamine receptor antagonists (antihistamines) to block the skin flushing response. However, our knowledge of the effects of antihistamines on the physiological responses of alcohol is poor. The purpose of this scoping review was to evaluate the current evidence of the effects of antihistamines on the physiological effects of alcohol among individuals with acute alcohol sensitivity and identify gaps in this literature. A scoping review was conducted to identify studies prior to March 2024 that administered alcohol and antihistamines to individuals with natural or induced alcohol sensitivity and examined the following physiological responses: skin flushing, heart rate, blood pressure, and skin temperature. Seven experimental studies were identified. Antihistamines showed some evidence in reducing alcohol-induced skin flushing, which was associated with a reduction in skin temperature. Antihistamines showed inconsistent effects on alcohol-associated changes in HR and BP. Antihistamines may attenuate alcohol skin flushing in alcohol-sensitive individuals with mixed and inconclusive effects on other physiological responses. Current evidence is limited by small sample sizes, inconsistent findings, and a lack of acetaldehyde measurement. These limitations highlight the urgent need for rigorous studies to clarify the health risks of alcohol-antihistamine co-use and to inform harm reduction strategies for vulnerable populations. Understanding these interactions is vital for public health to inform targeted education and interventions.