Venlafaxine can cause a marked increase in the antimuscarinic adverse effects of clomipramine, desipramine and nortriptyline. An isolated report describes seizures in a patient taking
venlafaxine with trimipramine, and
serotonin syndrome, developed in patients taking
venlafaxine and amitriptyline, with or without pethidine (meperidine).
Be alert for any evidence of increased antimuscarinic adverse effects. Although there appears to be only one report, the possibility of an increased risk of seizures with concurrent use should be borne in mind, especially in those already at risk of seizures. It may be necessary to withdraw one or other of the two drugs. The
reports of the
serotonin syndrome highlight the need for caution when one or more serotonergic drugs are given.