How unsafe is it to mix effexor (venlafaxine) with recreational drugs?

Yes: The scariest possibility is that the propensity of Effexor (venlafaxine) to elevate blood pressure without the presence of recreational drugs would be potentiated in the presence of any substance with a capacity for elevating blood pressure to the point of producing a catastrophic event such as a cerebrovascular hemorrhage. Also there is serotonin syndrome and hyponatremia in addition to severe behavior change.