What's the likelihood that hypertension could be caused by venlafaxine?

Possible: HTN is listed as one of the drugs SIDE effects.

None: This drug has no significant effect on BP. The common variety Hypertension is called essential Hypertension, in other words its cause is unknown, perhaps it is due to stress of modern life as it effects most people sometime during their life time.

It's possible: Hypertension is a known side effect of venlafaxine and it's risk increases with higher doses and is thought to be due to the norepinephrine (noradrenaline) effects of the medication. It's helpful to take blood pressure readings over many days to see if it stays elevated There are many causes of hypertension, so it's good to speak with a GP or psychiatrist in case further investigation is needed.