At what dose does effexor (venlafaxine) become an snri and is high blood pressure common with its use?

At least 150mg: One usually needs to get up to at least 150 mg to start to see the effects of the 2 neurotransmitter( serotonin plus norepinephrine ), and one needs to get to at least 225 before you may see the effect of the 3rd ( dopamine) come into play. Yes Effexor (venlafaxine) can affect BP; it should be monitored.

Usually 150 mg: The 5HT and Noradrengergic action can elevate BP. Best to check it before and after dose changes. High blood pressure is common in 49 year old American men without the use of Effexor (venlafaxine). At high doses > 300 mg Doapminergic effects may be seen. With serotonergic syndrome BP can be quite labile. This often occure when combined with other agents including Bupropron, triptans and MAO inhibitors.