I've been taking them maybe 10 days now.. my AF always messes with my tummys nerves acting up my irritable bowel syndrome.. ibs).. I'm used to it. But I'm like 5 days past AF and wondering if my vitamins are messing with my belly issues. I can deal with it because I'm anemic to I actually should've been on vitamins for a while. With prenatles I felt like I was helping get some iron and everything else my body needs in a decent amount.