Hi. If you have gained 100 lbs, you should really discuss that with your doctor - it sounds like you might benefit from changing meds. I took effexor for about 2 years, but just stopped it about 2 months ago. Weaning off of it was hard, and I'm still looking for the right "replacement" med, but hopefully things will improve soon
I didn't experience any weight gain, but found I was exhausted all the time.