As with other contraceptive methods, it is not foolproof, but when used properly and consistently it is 79 to 95 percent effective in preventing pregnancy. (advocatesaz.org)
Please, talk to your physician (MD, DO, ND) about other contraceptive options or ways to minimize the adverse affects of the pill on your health (I think ND's can be the most helpful here). (elixiawellness.com)
The Pill, Condoms and You has a detailed explanation about two of the most popular forms of birth control while Natural Birth Control will provide you with valuable information about other contraceptive methods. (pregnancy-info.net)