Venlafaxine Interactions

Venlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI). St. John's wort independently inhibits serotonin (and to a lesser extent norepinephrine and dopamine) reuptake. Combining them can drive synaptic serotonin higher and trigger serotonin syndrome, and St. John's wort can also reduce venlafaxine exposure by inducing drug-metabolizing enzymes such as CYP3A4.

Venlafaxine (Effexor) is an SNRI antidepressant, and alcohol is a central nervous system depressant. The FDA-approved label advises avoiding alcohol because the combination can add to drowsiness and dizziness and can worsen the mood or anxiety disorder being treated. The concern is about additive sedation, blood pressure, and undermined treatment rather than a dramatic pharmacokinetic clash, which is why it is rated moderate.