How to Use the Morning-After Pill

Choosing, Using, and Timing Emergency Contraceptive Pills

Morning-After Pills in plastic

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Emergency contraceptive pills can be taken when you have unprotected sex or you suspect the birth control method you used may have failed. For instance, maybe you and your partner used a condom and it broke, you forgot to take several of your birth control pills, or you were late getting your birth control injection. Here's what you need to know about taking emergency contraceptive pills.


Though most people know them as the "morning-after" pill, this isn't an accurate name since you can use emergency contraceptive pills for up to five days after unprotected sex. There are two types: over-the-counter and prescription.


Over-the-counter emergency contraceptive pills include the brand name Plan B One-Step, as well as a variety of generics like Next Choice One Dose, Take Action, and My Way. Each consists of one pill that contains 1.5 milligrams of levonorgestrel, a synthetic version of the hormone progesterone that has been used in many types of birth control pills for years. Levonorgestrel needs to be taken within three days of having sex.


The only emergency contraceptive pill that you can get with a prescription is called ella. This pill contains a substance called ulipristal acetate and you can take it up to five days after having sex.

One last option if you're already on a combination birth control pill (and depending on the pill you're on) is to take a certain number of them, usually four to five, in two doses within 12 hours of each other. However, using this method may not be as effective as Plan B or ella and it may also cause worse side effects. You'll need to talk to your doctor before using this option to make sure it'll work with your prescription.

How They Work

Though it's unclear exactly how emergency contraceptive pills work, evidence shows that they primarily prevent, or at least delay, ovulation so that there's no egg released to be fertilized for several days. They may also prevent sperm, which can live for up to five days in your body, from fertilizing an egg that has already been released. Lastly, they may change the lining of your uterus so that even if an egg does get fertilized, it won't be able to implant in your uterus, a source of major controversy over these pills.

That said, the jury is still out regarding whether or not emergency contraceptive pills, particularly Plan B, actually prevent implantation. Much of the research so far shows that Plan B and its generic equivalents don't have any effect on your uterine lining at all, so they wouldn't prevent a fertilized egg from implanting.

Similarly, other studies have shown that while Plan B is very effective when it's taken before ovulation, it's virtually ineffective when it's taken on the day you ovulate or after. This is further evidence that it probably doesn't affect anything that happens if fertilization occurs.

One thing is certain: Neither type of emergency contraceptive pill will affect an existing pregnancy, medically defined as beginning with implantation. They primarily work to stop or delay ovulation and/or prevent fertilization from happening at all.

This isn't the case if you use your combination birth control pills as emergency contraception—their main function is to prevent implantation of a fertilized egg, though they may also delay ovulation.


Plan B prevents pregnancy in around 7 out of 8 women, but timing is important. It's the most effective within 48 hours, and you should use it within three days after having unprotected sex. It may still be somewhat effective for up to five days afterward, depending on where you are in your menstrual cycle.

On the other hand, ella maintains its efficacy at a steady rate and it's approved for use up to five days after sex. It's about as effective as Plan B for the first 72 hours, but within that three- to five-day window afterward, ella is more effective.

Combination birth control pills are considered the least effective method of the three when they're used as emergency contraception. However, they may be a good option if you don't have access to anything else.

Whether emergency contraceptive pills work for you or not depends in part on two factors:

  • The amount of time that has gone by since you had sex: The sooner you take the pill, the more likely it is to keep you from getting pregnant.
  • The point in your cycle when you had sex: The closer you are to ovulation, the less effective the morning-after pill will be. If you've already ovulated, emergency contraceptive pills won't help.

How to Use

If you find yourself in need of emergency contraception, choosing and using over-the-counter levonorgestrel is easy. Generic versions are just as safe and effective as Plan B but do check the expiration date before buying it.

You can take the pill at any time of day. Again, the sooner after you've had sex, the better. In fact, it may be a good idea to have a package of the morning-after pill on hand so you can use it as quickly as possible if the need arises, rather than take time to go to the store. To make sure it will be effective, store it at room temperature and if you don't use it before it expires, toss it and replace it with a new one.

If it has been close to three days since you had unprotected sex or birth control failure, you may want to consider talking to your doctor about getting a prescription for ella instead.

Do read the directions and package insert first, especially so you know how you may feel after taking this emergency contraceptive. Thousands of women have taken the morning-after pill with no serious complications, though there are some common minor side effects.

Potential Side Effects

You may experience some common side effects of emergency contraceptive pills such as:

  • Nausea or vomiting (you may be able to avoid this by taking an over-the-counter nausea drug an hour before you take the pill)
  • Breast tenderness
  • Headache
  • Pain in the lower part of your abdomen
  • Fatigue
  • Dizziness

Taking the morning-after pill may affect your menstrual cycle, causing you to spot or have irregular bleeding before your next period, for example. It can also delay your period or cause it to come sooner than expected, although it will likely be within a week of your usual time. You may also have a heavier or lighter flow.

If any other adverse reactions occur after using the morning-after pill, you should call your doctor. You may also want to consult with your doctor if your scheduled period is more than seven days late, as this could indicate that you're pregnant.

If you develop severe abdominal pain three to five weeks after using the morning-after pill, you may have an ectopic pregnancy, in which a fertilized egg implants somewhere other than your uterus. This can have serious complications, so see your doctor right away.

How Long They Last

If an emergency contraceptive pill prevented you from getting pregnant, it has done its job. But remember that the pill won't continue to be effective. After you use it, your fertility will return, so don't take a chance and have unprotected sex. And remember that emergency contraceptive pills don't protect you from sexually transmitted diseases (STDs).

You can use Plan B more than once during the same month, but you should only use ella once per menstrual cycle; otherwise, its effectiveness can be decreased.

A Word From Verywell

Don't treat emergency contraceptive pills as a regular form of birth control. For one thing, they're not as reliable as other options. For another, your periods could become irregular and unpredictable and you may have more unpleasant side effects since you're exposing yourself to higher hormone levels. These pills can also end up being a lot more expensive than regular birth control. Talk to your doctor about the best birth control option for you.

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