I had the unfortunate experience of taking Zyprexa and gaining about 40 pounds. By the time I figured out why I was gaining so much weight I had put on 40 pounds. I'm not sure how common this side effect is but I do know several people who have had a similar experience. I would definitely speak with your doctor and let him or her know you are concerned about this drug. There are other meds in the same class that may be a better option. For example, I switched from Zyprexa to Seroquel and things have worked out well.