What is the difference between oral contraceptives?

Most birth control pills have a combination of estrogen and progesterone. The estrogen is the same in most pills and the progesterone accounts for difference in how the pill works and potential side effects or adverse reactions. The other major difference between oral contraceptives is that some pills have the same dose each day and others have a different dose weekly. All birth control pills provide contraception and relief from heavy, frequent or painful periods. If a patient has a problem with a certain pill, changing to a pill with a different progesterone or different dosing regime may resolve the issue.