#why does methadone make u gain weight?

It should not. Opinates/narcotics in general don't have weight-gain as a side effect. They actually can suppress appetite a bit and people may lose wt while on these meds. For some, taking Methadone may allow the person to return to normal functioning (ie the person was doing drugs) which may including working, socializing/eating more and thus wt gain. Consult doc as u may have thyroid problem now. Good luck.