Reviews and ratings for effexor xr. For Social Anxiety Disorder "Worked great for Social anxiety and anxiety, the downsides for me are loss of appetite and sexual dysfunction Had no luck ejaculating when I'm on it. Before that I was taking all sorts, up to 5 different ones at a time including Seroquel which put in weight. 5 Answers - Posted in: effexor, obesity, weight - Answer: Hello, Loss of appetite and weight loss are common side effects of this I was on effexor and while taking it, had no weight gain, and very little if any weight loss. I really stayed much Effexor XR - does effexor have a big weight gain.