Plan B stays in your system for about 5–6 days, depending on the type. Although there isn’t a limit on taking it multiple times, extra doses won’t make it more effective, and they can cause some unpleasant side effects.

There are three types of emergency contraception (EC) or “morning after” pills:

  • levonorgestrel (Plan B), a progestin-only pill
  • ulipristal acetate (Ella), a pill that’s a selective progesterone receptor modulator, meaning that it blocks progesterone
  • estrogen-progestin pills (birth control pills)

There’s generally no limit to how often you can take the Plan B pill (levonorgestrel) or its generic forms, but this doesn’t apply to other EC pills.

Here’s what you need to know about how frequently you can take EC pills, potential side effects, common misconceptions, and more.

Correct. Frequent use of progestin-only Plan B pills isn’t associated with any long-term side effects or complications.

However, you shouldn’t take Plan B pills if you’ve taken Ella (ulipristal acetate) since your last period.

Given this, you might be wondering why Plan B pills aren’t recommended as birth control if they’re indeed safe.

It’s because they’re less effective than other forms of contraception, such as the pill or condoms, at preventing pregnancy.

In other words, the most significant risk of long-term Plan B use is actually pregnancy.

According to a 2019 review, people who use EC pills on a regular basis have a 20 to 35 percent chance of becoming pregnant within a year.

Unlike Plan B, Ella should only be taken once during a menstrual cycle. It’s not known whether it’s safe or effective to take this pill more frequently.

You also shouldn’t take other birth control pills that contain progestin for at least 5 days after taking Ella. Your birth control pills can interfere with Ella, and you could get pregnant.

Ella is available only by prescription from a healthcare provider. It’s more effective at preventing pregnancy than other EC pills.

While you should take Plan B as soon as possible within 72 hours of having sex without a condom or other barrier method, you can take Ella as soon as possible within 120 hours (5 days).

You shouldn’t take Plan B or Ella at the same time or within 5 days of each other, because they could counteract each other and be ineffective.

Yes, although this method isn’t as effective as Plan B or Ella. It may cause more side effects like nausea and vomiting, too.

Many birth control pills contain estrogen and progestin, and may be taken in higher-than-usual dosages as emergency contraception.

To do this, take one dose as soon as possible up to 5 days after you’ve had sex without a condom or other barrier method. Take the second dose 12 hours later.

The number of pills you need to take per dose depends on the brand of birth control pill.

Ella (ulipristal acetate) should only be taken one time during your menstrual cycle.

Plan B (levonorgestrel) pills can be taken as many times as necessary per menstrual cycle. But you shouldn’t take Plan B pills if you’ve taken Ella since your last period.

Menstrual irregularity is the most common side effect of EC pills.

Depending on which EC pill you take and when you take it, these irregularities can include:

  • a shorter cycle
  • a longer period
  • spotting between periods

Taking additional doses of an EC pill won’t make it more effective.

If you’ve already taken the required dose, you don’t need to take an additional dose on the same day or the day after.

However, if you have sex without a condom or other barrier method 2 days in a row, you should take Plan B both times to reduce your risk for pregnancy for each case, unless you’ve taken Ella since your last period.

There are some disadvantages to using EC on a regular basis.

Reduced effectiveness compared to other contraceptives

EC pills are less effective in preventing pregnancy than other forms of birth control.

Some more effective methods of birth control include:

Cost

One dose of Plan B or its generic forms generally costs between $25 and $60.

One dose of Ella costs about $50 or more. It isn’t currently available in a generic form.

That’s more than most other forms of contraception, including the pill and condoms.

Short-term side effects

EC pills are more likely to cause side effects than some other methods of birth control. The section below lists common side effects.

Short-term side effects include:

  • nausea
  • vomiting
  • headaches
  • fatigue
  • dizziness
  • lower abdominal pain or cramps
  • tender breasts
  • spotting between periods
  • irregular or heavy menstruation

Generally, Plan B and Ella pills have fewer side effects than EC pills that contain both progestin and estrogen.

If you’re worried about side effects, ask your healthcare provider or a pharmacist for a progestin-only pill.

Side effects like headaches and nausea should fade within a few days.

Your next period might be delayed by up to a week, or it might be heavier than usual. These changes should only affect the period right after you take the EC pill.

If you don’t get your period within a week of when it was expected, you should take a pregnancy test.

There are no long-term risks associated with using an EC pill.

EC pills don’t cause infertility. This is a common misconception.

EC pills work by delaying or preventing ovulation, the stage in the menstrual cycle when an egg is released from the ovaries.

Current research strongly suggests that once an egg is fertilized, EC pills no longer work.

In addition, they’re no longer effective once the egg has been implanted in the uterus.

So, if you’re already pregnant, they won’t work. EC pills aren’t the same as the abortion pill.

There are no known long-term complications associated with taking EC pills. Common short-term side effects include nausea, headaches, and fatigue.

If you have questions about the morning-after pill or contraception, talk to your healthcare provider or local pharmacist.