Yes, you can take Plan B (levonorgestrel) while you're on birth control pills, and the CDC says you can keep taking your pills right away, with no pause. The CDC says there is no concern that taking them together makes either your pill or Plan B less effective. You do need to avoid sex or use condoms for the next 7 days. The other morning-after pill, ella (ulipristal), works differently: its label says to wait 5 days before going back to hormonal birth control.
When does Plan B make sense if I'm on the pill?
If you take your pill correctly, you are already protected and you don't need Plan B. It comes up when pills are missed or late and you had sex without a condom.
The CDC's missed pill guidance (the US SPR) sets out when emergency contraception is worth it. It depends on how many pills you missed, and when in the pack.
- Combined pill, 1 pill late or missed (less than 48 hours): take it as soon as you can and keep going. The CDC says emergency contraception is not usually needed, but may be considered if pills were missed earlier in the cycle or in the last week of the previous pack.
- Combined pill, 2 or more in a row missed (48 hours or more): the CDC says emergency contraception should be considered if the missed pills were in the first week of the pack and you had unprotected sex in the previous 5 days.
- Progestin-only pill (norethindrone or norgestrel), more than 3 hours late: the CDC says emergency contraception should be considered if you had unprotected sex.
- Drospirenone progestin-only pill (Slynd), 2 or more in a row missed: same as the combined pill, consider it if the misses were in the first week and you had unprotected sex in the previous 5 days.
- Vomiting or severe diarrhea for 48 hours or more on the combined pill counts like missed pills. The CDC says to consider emergency contraception if this happened in the first week of a new pack and you had unprotected sex in the previous 5 days.
Do I keep taking my pill after Plan B?
Yes. The CDC says any regular birth control method may be started or resumed immediately after levonorgestrel emergency contraception. Take your next pill at your usual time.
Follow your missed pill instructions as you normally would. For example, after 2 or more missed combined pills, the CDC says to take only the most recent missed pill, throw away the other missed ones, and finish the pack on schedule, even if that means 2 pills in 1 day.
The CDC also says there is no concern that taking levonorgestrel with hormonal birth control lowers the effectiveness of either one.
Do I need condoms after taking Plan B?
Yes. Plan B is for sex that already happened. Its label says it is not for regular birth control.
The CDC says to avoid sex or use a barrier method, like condoms, for 7 days after taking levonorgestrel.
Your missed pill rules may ask for backup too, for example 7 days of pills in a row after 2 or more missed combined pills. If both apply, follow whichever lasts longer.
Is ella different if I'm on the pill?
Yes, and this is the part that trips people up. Ella (ulipristal acetate) is a prescription morning-after pill that can be taken up to 120 hours (5 days) after sex. It works on the body's progesterone signals, and the pill contains a progestin, so they can work against each other.
The ella label says progestin-containing birth control may impair ella's ability to delay ovulation. It says to start or resume hormonal birth control no sooner than 5 days after taking ella, and to use a reliable barrier method until your next period.
This is also why the CDC's missed pill guidance for pill users names emergency contraception "with the exception of UPA" (ulipristal). If you want to keep taking your pill straight through, Plan B fits that plan. If you already took ella, don't restart your pill for 5 days, and use condoms until your next period.
- Plan B (levonorgestrel): over the counter, take within 72 hours, keep taking your pill right away, backup for 7 days.
- Ella (ulipristal): prescription, take within 120 hours, wait 5 days before your pill, backup until your next period.
How do I take Plan B, and what can stop it working?
The Plan B One-Step label says to take 1 tablet as soon as possible within 72 hours (3 days) after unprotected sex. The sooner you take it, the better it works. It is not for regular birth control and does not protect against STIs.
If you vomit within 2 hours of taking it, the label says to call a healthcare professional to find out if you should repeat the dose. The CDC's guidance for clinicians uses a 3 hour window and says another dose should be taken as soon as possible, so call a pharmacist or clinician if you vomit within 3 hours.
The label says efavirenz (an HIV medicine), rifampin (a tuberculosis medicine), and seizure medicines may make levonorgestrel less effective. Ask a pharmacist before you take it if you use any of these.
The CDC also notes levonorgestrel might be less effective than ella in people with obesity. If that applies to you, ask a pharmacist or clinician which option fits best.
When should you get care?
In an emergency, call 911Get care the same day if you have lower belly or pelvic pain or unusual vaginal bleeding after emergency contraception, especially if you could be pregnant. MedlinePlus lists these as reasons to contact a provider about possible ectopic pregnancy.
Talk to a clinician or pharmacist soon if you vomited within 3 hours of Plan B, or if you have no bleed within 3 weeks and need help with a pregnancy test result.
Call 911 if you have severe, sharp, sudden pain in your lower belly, feel faint or pass out, or have shoulder pain with belly pain. MedlinePlus lists these as signs a ruptured ectopic pregnancy may need emergency help.
How our AI doctor decides when to send you to care ›What should I watch for afterward?
Plan B can change your next bleed. The label lists menstrual changes, nausea, tiredness, headache, breast pain, lower belly pain, and dizziness as possible effects.
The CDC says to take a pregnancy test if you don't have a withdrawal bleed within 3 weeks. If you are pregnant after emergency contraception, the ella label says to consider the possibility of ectopic pregnancy, a pregnancy outside the uterus that needs medical care.
Common questions
Can I take Plan B while on birth control?
Yes. The CDC says you can keep taking your pills right away after levonorgestrel, and that taking them together does not lower the effectiveness of either one. Avoid sex or use condoms for the next 7 days.
Will Plan B mess up my pill pack?
No. Keep taking your pills at your usual time and follow your normal missed pill rules. Your next bleed may come earlier or later than usual, since the Plan B label lists menstrual changes as a possible effect.
Can I take ella if I'm on the pill?
You can, but the timing changes. The ella label says to wait at least 5 days after ella before starting or resuming hormonal birth control, and to use a barrier method until your next period. The label says a progestin pill may make ella less able to delay ovulation.
I only missed 1 pill. Do I need Plan B?
Usually not for the combined pill. The CDC says emergency contraception is not usually needed after 1 late or missed combined pill, but it may be considered if pills were missed earlier in the cycle or in the last week of the previous pack. For a norethindrone or norgestrel progestin-only pill, being more than 3 hours late is enough for the CDC to say consider it.
Do I need a pregnancy test after Plan B on the pill?
The CDC says to take one if you don't have a withdrawal bleed within 3 weeks. Seek care sooner if you have belly pain or unusual bleeding.
Pymander is not a replacement for a physician and does not provide medical advice, diagnosis, or treatment. Always seek the advice of a qualified health provider with questions about a medical condition. If you think you may have a medical emergency, call 911.