The Sex-Dependent Effect of Alcohol Consumption on Physiological Responses and Perception to Acute Heat Stress

Introduction: Public health agencies caution alcohol consumption during periods of extreme heat as it may impair thermoregulatory responses and exacerbate dehydration. Despite a sparsity of data confirming these outcomes, our research team recently concluded from a systematic review that no study has explored the physiological and perceptual effects of alcohol consumption in females during heat stress. Hypothesis: We hypothesize that biological sex will not independently alter the physiological response and perception during heat exposure. Methods: Participants completed two trials on separate days in random order. Upon arrival, participants voided their bladder, were instrumented, and entered a room maintained at 40°C & 25%RH. After a 30-minute baseline, they consumed either i) an alcoholic beverage (ALC, orange juice and 80-proof gin) sufficient to target a blood alcohol concentration of ~0.08 mg/ml, or ii) a volume matched placebo (PLA, orange juice and tonic) over 30 minutes, and the rested for 120 minutes. Blood alcohol concentration, core and mean skin temperature, whole-body sweating, heart rate, and skin blood flow were assessed at baseline (pre-drink) and every 30 minutes thereafter. Urine volume output was calculated from the sum of micturition following beverage consumption and immediately after heat stress. Results: 19 participants (10 males: 23±4 y, 82.0±11.6 kg, 1.8±0.1 m; 9 females: 23±3 y, 70.4±15.5 kg, 1.7±0.1 m) participated in this study. Mean blood alcohol content during the ALC trial was similar between sexes (males: 0.092±0.017; females: 0.086±0.016, p=0.30). Relative to PLA, alcohol resulted in a higher heart rate during heat exposure (males: +9±7 BPM; females: +8±10 BPM; p<0.001), with no difference observed between sexes (p=0.97). Skin blood flow was higher with ALC compared to PLA (males: +5±16%; females: +11±17%; p<0.001), with no difference between sexes (p=0.91). Mean arterial blood pressure during heat stress was lower with ALC compared to PLA (males: -4±8mmHg; females: -4±10; p=0.001), however the effect was similar between sexes (p=0.19). Urine volume was higher with ALC (males: +243±357mL; females: +447±227mL; p<0.001), with no effect of sex (p=0.10). The change in core temperature was unaffected by ALC (males: +0.06±0.22°C; females:+0.01±0.32°C; p=0.94) and not different between sexes (p=0.99). Mean skin temperature was not affected by ALC (males: +0.13±0.38°C; females: -0.02±0.60°C; p=0.88) or sex (p=0.99). While whole-body sweat loss was lower in females (p=0.002), sex did not independently modulate the whole-body sweating response following ALC (males: -17±144 g; females: 41±149; p=0.32). Thermal comfort was not affected by ALC (male: -9±27 mm; female:, -1±26 mm; p=0.18) and was not independently modified by sex (p=0.36). While thermal sensation was lower in females (p=0.01), sex did not modulate thermal sensation following ALC compared to PLA (male: -4±17 mm; female:, -3±22 mm; p=0.65). Conclusion: Biological sex did not independently alter the physiological response and perception to heat stress following alcohol consumption compared to placebo. Nonetheless, alcohol results in a higher heart rate and skin blood flow, lower mean blood pressure, and a greater risk of dehydration mediated through increased urine output. Dr. Ravanelli’s Lakehead University Research Funding and the Natural Sciences and Engineering Research Council of Canada Discovery Grant (PIN#2022-05096) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.