Why can prozac (fluoxetine) cause weight gain?always been skinny until i started it for panic/gad. now on 40 a day it causes extreme weight gain & fail to lose it.

Discuss with doctor: Hi, it isn't always clear if this is due to the medication, the nature of the illness, or if people eat more when they begin to feel better. If the benefits of taking the medication outweigh the weight gain, then consider making lifestyle changes (e.g., increased exercise and dietary management) to offset the side effect. Adjusting dose or changing meds might help. Hope this is helpful. Take care