Most people get their next period around the date they expected it. Plan B can move it a few days either way, and Mayo Clinic says it can be up to a week late. If three weeks have passed since you took the pill and no period has come, take a pregnancy test.
This guide covers levonorgestrel morning-after pills. That includes Plan B One-Step, Take Action, My Way and, in the UK, Levonelle. They all contain the same dose and work the same way. Ella is a different pill, but the three-week test rule applies to it too.
When should I get my period after taking Plan B?
Start from the date your period was due anyway. The pill works mainly by delaying ovulation, so it can shift the cycle you took it in. Here’s what to do depending on how things go.
| Your period | What to do |
|---|---|
| Comes a few days early | Common, especially if you took the pill early in your cycle. If it looks like your usual period, nothing to do. |
| Comes on time | The most common result. Nothing to do. |
| Up to a week late | Within what Mayo Clinic says the pill can cause. Keep waiting. |
| More than a week late | Take a pregnancy test. |
| None 3 weeks after the pill | Take a test even if an earlier one was negative. Planned Parenthood and Mayo Clinic both draw the line at three weeks. |
Not sure when your period was due? The late period calculator counts it from the first day of your last period.
Does it matter when in my cycle I took it?
Yes, and it’s why some people bleed early while others wait. Three studies followed people’s periods after a levonorgestrel pill. They came out of Cameroon in 2006, Italy in 2008 and the US in 2006. They disagree on how big the effect is, but the direction matches.
| When you took it | What the next period did |
|---|---|
| Early, before you ovulated | Often early. One study saw cycles shortened by about a day, another by nearly 11 days. |
| Around ovulation | About on time on average, though any one person can still be a few days either way. |
| After you ovulated | On time or a couple of days late. The period itself may last a little longer than usual. |
You usually don’t know for sure which side of ovulation you were on. As a rough guide, it comes about 14 days before your next period. On a 28-day cycle, the first week and a half counts as early. The ovulation guide works it out for other cycle lengths.
Bleeding a few days after Plan B. Is that my period?
Usually it isn’t. Light bleeding or spotting in the days after the pill is a side effect. In the Cameroon study, about 1 in 7 people had bleeding between periods after taking it. It’s usually lighter and shorter than a period.
Don’t count it as your period. Keep waiting for a bleed that looks like your normal one. Mayo Clinic says to call a doctor if the spotting keeps going.
My period came after Plan B. Does that mean it worked?
If it came around the usual time with your usual flow, pregnancy is unlikely. What to watch for is a bleed that was much lighter or shorter than normal, because early pregnancy can cause light bleeding around the time a period is due. If that’s what you had, a test will tell you. Our guide to an early period goes through how to tell the two apart.
Late period after Plan B and a negative test
The test may have been too early. The NHS says most tests work from the first day of a missed period. If you don’t know when that is, test at least 21 days after sex. A negative result a few days after taking the pill doesn’t tell you anything yet. The pregnancy test calculator gives you the first day a result counts.
If you test at three weeks and it’s still negative but there’s no period, test again a few days later. A period that stays away after two negative tests is worth a call to your doctor or a sexual health clinic.
Heavy or painful period after Plan B
A heavier period can happen. Planned Parenthood says the next one may be heavier, lighter or more spotty than you’re used to. The NHS lists period-like pain and cramping among the common side effects.
Heavy bleeding with pain in your stomach is different. Mayo Clinic says to call a doctor if you have it, because it can be a sign of a miscarriage or of a pregnancy outside the uterus. Get help the same day if the pain is strong or one-sided, or if you feel faint.
Will my cycle go back to normal?
Almost always, and quickly. In the Cameroon and Italy studies, most of the changes were gone by the cycle after. Expect one odd period, then your usual pattern. If your periods are still off two cycles later, something else is more likely the cause. Our guide to late periods covers the usual reasons.
Keeping track in Plum
Plum, a period tracker app for iPhone, has no separate entry for the morning-after pill. You can log the day as unprotected sex, then log spotting on its own so it isn’t counted as a period. Pregnancy tests can be logged as negative, positive or unclear. With the day logged, you know exactly when the three weeks are up.
