Pre-natal vitamin side effects

Yon

I've been taking Rainbow Light Prenatal one for a couple weeks now and not sure if I'm paranoid they'll poison me (I read you're not supposed to take prenatals if you're not pregnant)... I have mild heart burn, mild nausea and mild stomach discomfort.... Should I just deal? Do ppl get used to this? Gummies don't seem to have all of the vitamins recommended so I'm not that inclined to switch