If the condom, the pill, or hey, no protection at all has failed your pregnancy prevention plans, you might resort to Plan B.
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?
Can Plan B delay your period?
Since emergency contraception can affect the length of your menstrual cycle, your period might come about a week later or earlier than usual after taking Plan B.
It’s unlikely Plan B would mess up your cycle for months. So if you haven’t had a period about 2 weeks after taking the morning after pill, you could be pregnant.
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.
All the deets on Plan B
- What is it? Plan B One-Step is a type of emergency contraception (EC) or “morning-after” pill. It’s used after unprotected sex to prevent pregnancy.
- How’s it work? It contains the hormone levonorgestrel, a progestin type that can stop ovulation.
- When can you take it? It should be taken within 72 hours after the deed, but the sooner, the better. (Unless you’re taking the brand ella, which contains a different medication and can be taken within 5 days — but ASAP is always ideal.)
- How effective is it? EC pills with levonorgestrel can reduce pregnancy chances by 95 percent if taken within 24 hours, or 88 percent if taken between 24 and 72 hours.
- Where can you get it? In the U.S., you can get most types of emergency contraception over the counter. If you can’t afford it (it’s usually $40 to $50 for name brands or $11 to $40 for generics), you can visit a low-cost family planning clinic like Planned Parenthood.
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
After EC, your period might come late, early — or right on time. Remember, on average, it’s no more than a week either way.
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.
Plan B can cause side effects like nausea, cramps, or headaches, but these symptoms should go away within 24 hours. If cramping persists, it’s likely just your period.
If you have a heavier period after taking Plan B, you might feel extra tired or lethargic.
Go-to period products to go with the flow
Typically there’s no need to get anything special after Plan B — your regular period products should cover it.
But if your period is extra heavy, you may want to consider an extra layer of protection. For instance, if you use tampons or a menstrual cup, you might want to layer up with a pad or leak-proof period underwear.
To make matters more bloody confusing, it’s normal to experience some spotting or light bleeding after Plan B that’s not actually your period. This is a normal side effect of those extra hormones.
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:
- stomach pain
- breast tenderness
PSA: In rare cases, spotting could also signal an early pregnancy, so track your cycle and take a pregnancy test if you feel unsure.
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 you take Plan B and your period is over a week late, there’s a slight chance that you might be pregnant. Take a pregnancy test to play it safe.
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.
If you’re not sure what stage of your cycle you’re at or you have irregular periods, Planned Parenthood recommends waiting 3 weeks after taking Plan B before you take a pregnancy test.
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.
If your period is still MIA 2 months after taking Plan B, you could be pregnant. It’s unlikely it’s the EC still messing with your cycle.
Take a pregnancy test and visit a doctor or midwife ASAP to know for sure.
Other things that can delay your period include:
- chronic illness
- anxiety and depression
- low body weight
- polycystic ovary syndrome (PCOS)
- thyroid issues
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.
By your second period post-Plan B, everything should return to normal. If you’re still experiencing irregular periods, talk with your doc.