Hi. I have been on Lamictal just for a short time and definitely have the sore muscles...however, I luckily haven't gained any weight. I was on Effexor a number of years ago and gained 40 pounds within 2 months - even though I worked out and ate normally. Maybe it's your Effexor and not the Lamictal. I'm now on Wellbutrin and have done ok so far.
lesser of the evils sore muscles anti depressants therapeutic dose weight gain bipolar rash acne lamictal effexor wellbutrin short time