After taking an emergency contraception (EC) — aka morning-after pill — like Plan B One-Step it’s normal to eagerly await a sign this backup method did its thing. For once, you can’t wait for your period to show up! But what if your flow is still on the fritz?
Here’s what to know about how EC can affect your period.
If you’re staring at the clock waiting for your period to show up, we feel you.
Even though EC can cause your period to come at any time from a week early to a week late, everyone’s different. It’s possible that it can take even longer for your flow to return. But after about 2 weeks, the chance you’re actually pregnant goes up.
What’s to blame for the delay? That extra-strong dose of levonorgestrel (a type of synthetic progesterone — aka progestin). Though some hormonal birth control pills also contain levonorgestrel to prevent pregnancy, the morning after pill has it in much higher quantities. This can do a number on your menstrual cycle, including delaying your period.
In a 2007 study, researchers found that about 15 percent of participants who took Plan B experienced significant changes in menstrual cycle length, period length, and menstrual appearance.
Here’s what might happen when you get your flow back.
Timing and delays
Research from 2006 suggests that the earlier in your cycle you take Plan B, the earlier your next period will be. But the research isn’t conclusive so we don’t know if this is 10/10 true for all EC users.
That same 2006 study found that taking EC can make your period last longer than normal. This was the case if the morning after pill was taken after ovulation. Your period length might also stay exactly the same.
Your post-Plan B period might be lighter or heavier than usual.
According to an FDA report, about 31 percent of women experience heavy flows after taking Plan B. Heavier bleeding is even more likely if you’ve taken the pill more than once in a month.
If you have a heavier period after taking Plan B, you might feel extra tired or lethargic.
Here’s how to *spot* the difference between your period and Plan B bleeding:
- Keep tabs on timing. Plan B bleeding usually starts flowing a few days after taking the pill.
- Pay close attention to duration. Plan B spotting usually only lasts a day or 2, but it’s possible that it could last a little longer.
- Super light bleeding. Spotting won’t look exactly like your usual period. It’s usually a much lighter color and it might only be a few drops of blood.
- Check out the signs and symptoms. It’s unlikely you’ll experience all of your regular period probs like serious cramps and mood swings. However, Plan B can come with other side effects that usually disappear after 24 hours like:
Most likely, your period will be business as usual by your second cycle after Plan B.
In a 2007 study, researchers found that the majority of participants who initially experienced menstrual changes from EC didn’t experience recurring symptoms in their second period.
Plan B is 95 percent effective if taken within a day after sex and 88 percent if taken between 3 days after. But there’s always a slim chance it won’t work.
If it’s been 2 weeks, your pregnancy odds are even greater and you should likewise take a test. If your pregnancy test is positive, visit a doctor or midwife to confirm your result and walk you through your options.
Pregnancy tests measure the hormone human chorionic gonadotropin (hCG), which the body starts to produce a few days after conception. So if you take a test too early, it could show a false-negative result.
Take a pregnancy test and visit a doctor or midwife ASAP to know for sure.
Other things that can delay your period include:
Plan B impacts everyone differently, so it’s tough to predict how it will affect your menstrual cycle.
If your first period after taking EC is a few days earlier or later than normal, it’s probably nothing to worry about. After a week, take a pregnancy test.