Like "Some have a lot of trouble with metformin...Something like 1 out of every 20 people cant take it...I would express this to your Doctor for sure.. 500mg i think is a normal starting dose for they must wonder if your sensitive to it if they're bringin it that far down?...I think breathing issues is the most severe side effect from it, that and vomiting...if you have those effects you should let them know a.s.a.p. and come off it... "