Gabapentin lists a side effect as a weight gain. I've gained weight on both Gabapentin & Lyrica, which I found to be allergic to after taking it for 4 years.

I gained a lot of weight on it, I'm not taking it anymore.

No not at all. I take 1800 mg a day. You do get immune and have to go up in dosage.

I have been on Gabapentin for about a year now. I had a hip fracture last year that everyone thought was part of a fibro flare. I knew better as the pain was unlike any I had experienced previously and I have gone out on a forced disability retirement in 2010 due in large part to the fibro (and related migraines with all the pain causing me to go into adrenal crisis every month that year requiring hospitalization}. Anyway, until they could get the MRI results proving there was more going on I was willing to take the Gabapentin. My rheumatologist actually increased my bedtime dose to see if i might sleep. Problem is I have gained 70 pounds since going on the drug. My neurologist was shocked when he saw me but when he heard about the Gabapentin he said it is in the same family as Lyrica and even my cells were swollen.....if I could get off of it I might be able to lose some of the weight but it would take some time. The problem is i have had to take a lot of Prednisone over and above my daily maintenance dose and now have Cushing's Syndrome. Steroids save my life but area a bear on the scales! I see my rheumatologist next month and I am going to take with her about my meds. I have to lose this weight. right now I am nursing a broken foot on the same leg that I had the rod the length of my femur that touches my prosthesis of my knee replacement. Mobility is extremely limited. My traumatic ortho surgeon wants me to bear no weight to try to avoid surgery (which is the same approach we tried with my hip for 3 months until it was determined there was no healing and I had to have the surgery which totally set off a flare and put me into adrenal crisis). I will see him in 6 weeks to see if i have healed adequately. Given all the pain I am having and knowing pain can easily put me in the hospital, it seems vain that I am concerned about my weight but this is not about fitting in all my old clothes - this is about limiting the number of stress fractures and keeping the knee replacement as I cannot go through a recovery like that again....not that I could not do the hard work of rehab. I was ready for that. It was the 4-5 xs in the hospital in adrenal crisis because my body couldn't handle it.
I said all that to say that yes, Gabapentin has caused me to gain weight. Yes, Prednisone has not helped the situation, niether has Cymbalta. Unfortunately, my fibro pain is controlled rather well right now it is just the damage the weight is doing to the rest of me - and yes - emotionally as well in that I do feel like a manatee right now and would rather stay in my house than leave especially with this doggone boot on my left foot/leg!

I'm on Lyrica and hormones and have gained weight. Very upsetting because I had gastric bypass in 2002. Really don't want to be going backwards after all these years of holding my weight steady. Frustrates the hell out of me!