Metformin can cause nausea, particularly when initiated at high doses, but titration can mitigate this side effect.

“Little downside, typically worst side effect is a queasy stomach that is mitigated by food”

“of nausea for about two months and again some people if they just go straight to a high dose they do feel nauseous others usually when i put patients on it now we titrate them we go 500 at night then 500 bid a thousand at night 500 in the morning etc so that was my first beyond that i didn't even notice i was taking it so never a side effect again”