A woman who has not recently given birth can start taking oral contraceptive (OC) pills any time, as long as she is reasonably sure she is not pregnant.

If the woman begins taking combined pills (COCs) during the first seven days after her menstrual period begins, or progestin-only pills (POPs) during the first five days, she does not need a back-up contraceptive method since the risk of conception is virtually nil.

If a woman starts COCs after the seventh day of onset of menses or POPs after the fifth day, she should use a back-up contraceptive during the first month.

If a woman is breastfeeding, she may begin COCs at six months postpartum or when she quits breastfeeding. COCs contain estrogen and may decrease breastmilk production. Breastfeeding women can safely start taking POPs six weeks after delivery, since they do not contain estrogen.

Postpartum women who are not breastfeeding may begin taking COCs three weeks after delivery. POPs can be taken immediately after delivery.

After abortion, women may begin oral contraceptives immediately. No back-up contraceptive is needed for COCs if the woman begins within the first seven days following abortion, or for POPs if she begins within five days.

Pills should be taken every day, even if the woman is not having sex daily. Pill users should have available a back-up contraceptive method, such as condoms, in case of missed pills.

If a woman misses one active (hormone-containing) COC, she is not likely to become pregnant. When this happens, she should take the missed pill as soon as she remembers, then take the next pill at the regular time even if this means she takes two pills in one day. No back-up contraceptive method is necessary when one pill is missed.

If a woman misses two or more active COC pills in a row, she should take an active pill daily for at least seven consecutive days. During this time, she should abstain from sex or use a back-up contraceptive.

If her pill pack has fewer than seven active pills remaining, she should finish the remaining active pills and start a new pack immediately (without using inactive pills of the old pack or taking a seven-day break from pill-taking). In this case, the woman will not have her menstrual bleeding at her regular time. If her pack has at least seven pills remaining, she should complete the pack and take her standard hormone-free break.

With POPs, a woman who misses one or more pills should take the most recently missed pill as soon as she remembers and the next pill at the regular time, even if that means taking two pills in one day. She should use a back-up contraceptive or abstain from sex for 48 hours.

Clients who often forget pills should discuss their pill-taking habits with providers, who can advise on how to take pills more effectively or suggest alternative contraceptive methods.

A woman can stop taking pills or switch to another method any time. She may do so without finishing a pill pack.

Fertility returns rapidly after pills are discontinued.

Women who discontinue OCs are likely to experience temporary spotting or bleeding.

Women who want to prevent pregnancy but want to stop taking pills should consider starting another contraceptive method before they discontinue OCs.

A woman who switches from COCs to POPs should begin POP use immediately after the last active COC pill.

A woman who switches to certain contraceptive methods may need a back-up contraceptive until the new method becomes effective. However, if the woman begins another hormonal method within seven days of taking her last active pill, she does not need a back-up method.