Background The impact of COVID-induced stress on mental health and alcohol use has been demonstrated in recent research. However, there is a lack of longitudinal data since most studies reported on cross-sectional data. It remains unclear how alcohol use develops under the dynamic changes of the pandemic. Therefore, the present study aims to investigate the general development of alcohol use and the impact of COVID related stress on drinking behavior in a German population-based sample during the pandemic in 2020. Methods In the longitudinal design with three measurements (baseline [T1] and two follow-ups [T2, T3]) an online survey was administered. The survey included the Alcohol Use Disorder Identification Test (AUDIT) as well as the assessment of the drinking days in the last 30 days, the number of alcoholic beverages on each occasion and changes in alcohol use in the previous fourteen days. Further, COVID-19 related concerns, perceived stress, worries about friends and family and worries about the financial situation were also assessed and multiple linear regressions and confidence intervals (CI) were calculated. Results 1050 participants started the survey, 756 participants (71.4%), 317 (52.7%) participants completed the survey at all three measurements. Seventy six percent (n = 241) of the sample were female. An increase in alcohol use in the previous 14 days was reported by 10.9% at T1, 3.9% at T2 and 3.6% at T3. Moreover, a decrease in alcohol use in the previous 14 days was reported by 8.7% at T1, 6.5% at T2 and 4.1% at T3. The number of drinking days was significantly higher at T2 than at baseline (p < .001; F = - 2.06, [CI - 3.10, - 1.02]). COVID-19 related concerns and stress were associated with a higher number of drinking days and average number of drinks at a typical occasion. AUDIT score at baseline positively predicted number of drinking days as well as average number of drinks. Conclusions The significant increases in alcohol use is a public health issue during COVID-19 pandemic. The findings show that especially people who drink more hazardously previously tend to drink more under pandemic conditions. Those individuals are particularly at risk for developing substance-related problems.
