Are there any vitamins that affect or decrease the effectiveness of the birth control pill?

Vits and BC pills: Certain medications can interfere with birth control pills and decrease their effectiveness, and certain vitamins may do the same. The birth control pills might interfere with vitamin absorption, as well. In general though, Vitamins are fine to take while on BC. Pills prevent Preg, but do not prevent STI's-so use condoms too. Always tell your doctor about any vitamins you take before starting birth control pills.