What is the effectiveness of birth control? after i start taking the pill, how long before it will be effective?

At : At least 1 week of taking the active pills in the pack to be effective. However, given that you are likely taking the pills to prevent pregnancy, i would use alternative contraception(condoms, etc.) for one month, until you start your second pack of pills to be extra safe. Also, remember that birth control pills help prevent pregnancy, but do not protect against sexually transmitted infections.

Excellent, but...: With no missed pills, "perfect use", the failure rate is 0.3%->99% effective.In typical use, because taking a pill every d without ever missing is hard, about 9/100 couples will get pregnant/year.Effective after 7 days.If you have a hard time remembering daily meds, ask your doctor about long-acting reversible contraception(larc)--iuds or an implant under the skin-easy, very effective, lasts 3-10 yrs.