A critical review of the effects of nicotine and alcohol co-administration in human laboratory studies

Simultaneous use of cigarettes and alcohol is common, and may be driven by nicotine increasing alcohol self-administration or vice versa. To better evaluate the causal nature of this relationship, we systematically reviewed human experimental laboratory studies that co-administered nicotine and alcohol with control conditions. Searches of PubMed/MEDLINE and PsycINFO databases and study bibliographies identified 30 studies that met our inclusion criteria. Research methodologies were critically reviewed. Effects of co-administration on drug self-administration and related factors such as craving, subjective response, motivation, and heart rate are reported. Results most strongly supported that alcohol increases nicotine and cigarette self-administration; whereas, depending on the context, nicotine increased, decreased, or had no effect on alcohol self-administration. Craving and subjective drug effects were also impacted by co-administration. Interaction effects of nicotine and alcohol on self-administration and subjective responses were reported infrequently. The effects may be moderated by a number of factors, including dose of administered drug and sex. Recommendations are made for future research and clinical and policy implications of findings are discussed.