The effects of fluoxetine, a relatively selective long-acting serotonin uptake inhibitor, on the consumption of alcoholic and nonalcoholic drinks, cigarette smoking, and body weight were assessed in 29 men who were early stage problem drinkers. After a 2-week baseline, subjects were randomly assigned to receive 40 mg/day fluoxetine (n = 8), 60 mg/day fluoxetine (n = 11), or placebo (n = 10) for 4 weeks. Fluoxetine 60 mg/day decreased mean daily alcoholic drinks from (X +/- SEM) 8.3 +/- 0.7 during baseline to 6.9 +/- 0.7 and decreased total drinks per 14 days from 115.8 +/- 9.3 to 96.5 +/- 9.5 (p less than 0.01; 17.3% decrease from baseline), with no significant increase in days of abstinence. Neither 40 mg/day fluoxetine nor placebo had effects on intake of alcohol. Fluoxetine 60 mg/day decreased total and mean daily alcoholic drinks compared with 40 mg/day fluoxetine (ANCOVA, both p less than 0.02), but neither dose of fluoxetine was different from placebo. Compared with placebo, both 40 mg/day fluoxetine and 60 mg/day fluoxetine no differences were detected between treatment groups, 60 mg/day fluoxetine increased mean daily nonalcoholic beverages from baseline (5.0 +/- 0.4 to 5.6 +/- 0.3, p less than 0.01) and increased daily cigarettes smoked (from 25.1 +/- 4.6 to 26.9 +/- 4.5, p less than 0.05), whereas no significant changes from baseline were observed with 40 mg/day fluoxetine or placebo.(ABSTRACT TRUNCATED AT 250 WORDS)