I was wondering the same thing, I just started the patch, but I have been on birth control for over 4 years. I just recently bought multivitamins by olay( I didn't know they made vitamins) but I haven't taken them yet because they are huge and I don't think that I could swollow them, but also I don't know if they would interact? I think that other medicine's like prescriptions could interact with birth control and make it less effective, but I don't think vitamins would, but then again I am not a doctor, but next time I go there, I will ask.