The effectiveness of birth control pills depends on the type of pill and when it is started during the menstrual cycle:
- Combination pills (containing estrogen and progestin) are effective immediately if taken within the first 5 days of the period starting. If started at any other time, they take 7 days to become effective.
- Progestin-only pills, also called the "mini-pill," can work immediately if taken within the first 5 days of the menstrual cycle. If started after day 5, they take 2 days to become effective.
- After childbirth or pregnancy termination, starting either pill within 5 days results in immediate effectiveness; otherwise, combination pills take 7 days and progestin-only pills take 2 days to be effective.
- It is recommended to use a backup birth control method during the initial waiting period.
In summary, birth control pills can take from immediately up to 7 days to be fully effective depending on the pill type and timing of initiation within the menstrual cycle.
