Smoking rate seems to be higher among patients with schizophrenia, comparing to other psychiatric entities, mainly in those who are on typical antipsychotics. Tobacco is known to have enzyme inducer properties, due to cytochrome P450 complex activity: CYP1A1, CYP1A2, CYP2E1 and CYP2D6. CYP2D6 and CYP1A2 play an important role in antipsychotics metabolism, mainly in the first generation ones, like haloperidol, despite its importance in risperidone metabolism.

To analyze the importance of tobacco smoking in patients taking long-action injections.

To investigate how sexual dysfunction varies with tobacco smoking, in patients taking long-action injections.

Individuals from both sexes, from 18 to 55 years old, taking antipsychotic long-action injections, answered the Arizona Sexual Experience Scale (ASEX).

In the studied population (n = 44), there were 20 individuals on haloperidol and 24 individuals on risperidone. In a total of 18 (40.9%) positive results for sexual dysfunction, 6 were on haloperidol (30%), 12 (50%) were on risperidone. Seventeen individuals of the 20 who were on haloperidol were smokers, but only 4 were considered to have sexual dysfunction, 35.3%; 12 of the 24 individuals who were on risperidone were smokers, but only 5 were considered to have sexual dysfunction, 41.7%.

Patients treated with haloperidol smoke more, comparing to risperidone. Sexual dysfunction is more frequent in patients taking risperidone than in patients taking haloperidol. This data supports that CYP2D6-CYP1A2 induction by tobacco, mainly interacts with haloperidol, which may be helpful for patients to try less side effects.

The authors have not supplied their declaration of competing interest.