Prenatal Multivitamins - I've been taking prenatal vitamins for about 6 weeks and notices the following symptoms: shorthness of breath, nasal cavity becomes swollen and rashes on my face. Been to the different doctors and none were able to help me. I'm just doing a trail and error to see if I'm allergic to the prenatal vitamins. I've been off of them for about a week now and still see no side of improvement. I was wondering how long does it take an allergic reacation to go away?