A recently published Cochrane review1 explores how various levels of alcohol consumption affect blood pressure and heart rate on the short term. Results show that within hours, a low amount of alcohol does not affect blood pressure, but a moderate amount of alcohol lowers blood pressure. Both low and moderate amounts slightly increase heart rate on the short-term.
What is already known? The long-term effects of alcohol consumption on blood pressure and risk of hypertension are extensively studied by observational studies, showing that heavy alcohol consumption is related to an increased blood pressure2,3. The effect of low to moderate alcohol consumption is less clear and seems to differ per gender and race3. The acute effects of alcohol could help explain these relations. A review from 2005 found that alcohol decreases blood pressure in the hours after drinking, but that the blood pressure increases the next day4.
What is new? For the first time, this review systematically looks at the short-term effects (<24 hours) of different amounts of alcohol on blood pressure and heart rate.
High quality review
Cochrane reviews are always very extensive and are internationally recognized as the highest standard in evidence-based health care. This current study looks at 32 randomized controlled trials (RCTs), with over 750 participants. RCTs are studies that can prove a causal relationship, meaning that it is quite certain that the alcohol is responsible for the changes in blood pressure or heart rate.
Short-term effects of alcohol
The researchers found that low amounts of alcohol (<14 gram, about 1.5 drinks) increase heart rate, but not blood pressure, within the first 6 hours. A moderate amount (14-30-gram) slightly lowers systolic blood pressure by ± 5,6 mm Hg, diastolic pressure by 4 mm Hg, and increases heart rate by five beats per minute. The effects were only present within the first 6 hours. The effect of low-to-medium alcohol consumption on blood pressure or heart rate after 7 hours is not yet clear because not enough studies are conducted.
It is important to note that these are very short-term effects. As the previously mentioned review4 showed, blood pressure tends to decrease the day of drinking, but increase the day after. This Cochrane study only looks at the first 24 hours after drinking.
- Only RCT’s included
- Effect measured for different alcohol dosages and multiple time spans
- Assessment of publication bias and sensitivity analysis
- Study population limited to healthy, relatively young males
- Methodological differences in assessment of blood pressure
- Evidence varied greatly between dosages
2. Roerecke, M., Tobe, S. W., Kaczorowski, J., Bacon, S. L., Vafaei, A., Hasan, O. S., … & Rehm, J. (2018). Sex‐specific associations between alcohol consumption and incidence of hypertension: a systematic review and meta‐analysis of cohort studies. Journal of the American Heart Association, 7(13), e008202.
3. Liu, F. et al. (2020). Race- and sex-specific association between alcohol consumption and hypertension in 22 cohort studies: A systematic review and meta-analysis. Nutrition, Metabolism and Cardiovascular Diseases, Volume 30, Issue 8, 1249 – 1259