I just had unprotected sex. What is emergency contraception? Is it the same as the “morning-after pill”?

It depends on what you mean by “just,” and it depends on what you mean by “sex.” If you had unprotected penile-vaginal sex in the last five days, you can take emergency contraception (EC)—also known as the “morning-after pill.” EC can be taken up to 120 hours (five days) after having unprotected penile-vaginal sex. EC should be taken as soon as possible though, as this increases the chance that it will prevent pregnancy. The sooner you take EC, the better. It can reduce the chance of a pregnancy by up to 89 percent.

EC is basically a high dose of certain types of birth control pills. Some of the current brand names for EC in the U.S. are Plan B One-Step, ella and Next Choice. Plan B One-Step and ella require that you take one pill. Next Choice requires you to take two pills, 12 hours apart. Read the instructions on the package to be sure you are taking the medication properly. Plan B One-Step emergency contraception may not be as effective at preventing pregnancy in people over 176 pounds. If you weigh over 176 pounds and need emergency contraception, you should speak to a health care provider about possibly using another emergency contraceptive pill or a copper IUD, which can be used as a form of EC.

EC is not an abortion; it works by preventing pregnancy before it happens. EC will not end a pregnancy that has already started. This is why it’s so important to take it as soon as possible after unprotected sex. Unprotected sex includes not using any method of birth control or condoms, being a survivor of rape or sexual assault or having a method fail (like a condom breaking).

You can get Plan B One-Step without a prescription over the counter at a local pharmacy. Next Choice One Dose, Take Action and other generic brands of Plan B One-Step are also approved for sale over the counter. ella is only available with a prescription regardless of age. If you need a prescription for EC, you can find a health care provider near you.

As with any birth control pills, there are some possible side effects to taking EC. Some people may experience side effects, but many don’t experience any at all. The most common side effects are nausea, pain in the lower abdomen, changes in the menstrual cycle, headache, fatigue and dizziness.

EC provides no protection against HIV or other sexually transmitted diseases (STDs). And if a couple had unprotected sex, either or both partners could be at risk for an STD. Anyone who has unprotected sex should get tested for STDs.

Find a clinic that provides EC, STD testing and other sexual health services.