Major
duloxetine × venlafaxine
SNRI×SNRI (serotonin-norepinephrine reuptake inhibitor)
Mechanism
Dual SNRI – doubling the same pharmacological effect without therapeutic benefit. Risk of serotonin syndrome, hypertension, and tachycardia.
Symptoms
Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia. Autonomic features: sweating, tachycardia, hypertension, fever. First signs appear within hours of co-administration.
Management
The combination is not prescribed. Choose one: venlafaxine for depression or generalised anxiety disorder, duloxetine for pain syndromes (diabetic neuropathy, fibromyalgia). When switching, allow a 1-week washout.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.