How long do vitamins take to digest?

I ask because usually mornings are my best time of day - I don't have any problems keeping food down. Not today. I had two pieces of toast and a sip of water to take my vitamins and within 20 minutes it all came back up. I take One-A-Day prenatal vitamins. There are two - one regular prenatal vitamin and a dha supplement. The dha is in capsule form and I did notice that in the toilet after I threw up (just the shell though). I didn't notice the pink vitamin or have any pink vomit (sorry - hope no one's tummy is queasy this morning!). I'm not too worried about the dha, I just want to make sure the vitamin stayed down. Is 20 minutes or so enough time for it to digest? Should I take another one (it will have to be later because now my stomach is empty)?