Search strategy
PubMed, The Cochrane Library, Web of Science, and Embase databases were searched from the date of their inception to August 15, 2021. In addition, supplementary searches were conducted through the WHO International Clinical Trials Registry Platform (ICTRP) search portal and grey literature. The main search strategies were as follows: (smok* OR cigarette OR tobacco OR nicotine) AND (Alcohol* OR drink) AND (cessation OR quit* OR abstinence OR stop*) AND (drug OR medicine OR pharmaco*) AND (“random*” OR “blind*” OR “single-blind*” OR “double-blind*” OR “treble-blind*” OR “triple-blind*”).