Learn about Effexor XR (Venlafaxine Hydrochloride Extended-Release) may treat, uses, dosage, side effects, drug interactions, warnings, patient labelingIf concomitant use of Effexor XR with other serotonergic drugs (e.g., triptans, tricyclic antidepressants, mirtazapine, fentanyl, lithium, tramadol...