Ay, common yan! A few of us had the same problem, lalo na pag naulan or stressed kami that morning, mas masaya ang tummy pag may solid food muna bago vitamins, or try taking it with milk instead of just water. Since nabura mo agad within 20 minutes, most likely hindi na absorbed ng body kaya it's safer to take another one later, pero best check with your OB kung dapat double dose or if you should take it differently para hindi maulit, they might suggest taking it before bed or with a heavier snack.