Emergency contraceptives like Plan B, also known as the morning-after pill, are a safe and effective way to prevent pregnancy after unprotected sex. They are legal nationwide, though they can be easier to access in some states than in others.
How does it work?
There are two main types of oral emergency contraception.
One is a pill that contains levonorgestrel, a type of synthetic hormone. It is perhaps best-known by the brand name Plan B One-Step, but other types of emergency contraceptives with levonorgestrel include AfterPill, My Way, Next Choice One Dose and Take Action.
These types of pills work primarily by stopping the ovaries from releasing an egg, said Dr. Alison Edelman, a professor of obstetrics and gynecology at Oregon Health & Science University in Portland. They should be taken within 72 hours after having unprotected sex.
Another type of pill, known by the brand name Ella, contains the drug ulipristal acetate. It works primarily by delaying the release of an egg from the ovaries, Dr. Edelman said. It can be taken up to 5 days after having unprotected sex.
Both these types of emergency contraceptive pills have been shown to reduce the risk of pregnancy, though Ella is more effective than Plan B. In clinical trials for Ella, pregnancy rates for users ranged from 0.9 percent to 2.1 percent, while pregnancy rates for levonorgestrel-based options ranged from 0.6 to 3.1 percent.
The sooner you take an emergency contraceptive after unprotected sex, the more effective it is likely to be, said Dr. Monica Woll Rosen, an obstetrician-gynecologist at the University of Michigan Medical School.
“It stops those normal cyclic changes from happening,” she said.
The Food and Drug Administration has said there is no evidence that Plan B prevents an egg that has already been fertilized from being implanted in the uterus or that it disrupts pregnancy.
How do you obtain the morning-after pill?
Plan B and other levonorgestrel-based emergency contraceptives are available over the counter at pharmacies, drugstores and grocery stores. The pills can also be purchased from Amazon and other online retailers.
If you’re buying it at one of these locations, the cost of a dose of Plan B One-Step or generic versions of it can range from about $15 to $50, said Megan Kavanaugh, a principal research scientist at the Guttmacher Institute, a reproductive health research organization. Community health clinics like Planned Parenthood may offer discounted rates. Or, if you have insurance, getting a prescription can cut the cost entirely.
Ella requires a prescription and typically costs about $50 out of pocket, according to Planned Parenthood. Under the Affordable Care Act, most insurance plans cover prescriptions for F.D.A. approved contraceptives, including birth control and morning-after pills, at no cost.
Can you get them in advance?
Dr. Edelman advised that anyone who is sexually active and of reproductive age keep a dose of Plan B or Ella on hand.
“I liken it to any other emergency equipment or medications that you might have on hand — like a fire extinguisher,” Dr. Edelman said. “You want it there in case of emergency.”
The shelf life for emergency contraceptive pills is three to four years, though you should check the expiration date to be sure. They are best stored in non-humid environments with a steady temperature, Dr. Edelman said. So if you want to hold on to them for the longer term, the bathroom medicine cabinet may not be the best place.
Is there a weight limit to use these products?
Studies have shown that Plan B and other oral contraceptives with levonorgestrel can be less effective in people who are above a certain weight, starting at around 154 pounds, or who have a body mass index over 25, but there is not a weight limit to use the pills.
Doctors tend to recommend Ella for people in these categories, Dr. Edelman said. Her own recent research showed that a standard dose of Ella was sufficient to delay ovulation regardless of B.M.I. or weight.
But Dr. Edelman said that if someone has easier access to Plan B, she would “absolutely recommend taking Plan B over taking nothing at all.”
Are there side effects?
It’s normal to bleed within a few days after taking an emergency contraceptive pill, Dr. Rosen said, which surprises some patients. And taking the pill might shift the timing of your menstrual period earlier or later. People can also feel nauseated and experience vomiting after taking oral emergency contraceptives. Overall, though, these medications are very safe.
“There’s nothing dangerous about taking Plan B,” said Dr. Colleen Denny, director of family planning at NYU Langone Hospital-Brooklyn.
Should I take it if I’m on birth control?
If you are already on oral birth control and consistent about taking it, you do not need to use emergency contraception, Dr. Edelman said. If you miss a day, follow the instructions in your pill pack on how to adjust your dosing.
If you already have any type of IUD, you do not need to use emergency contraception either.
Dr. Edelman added that it is a myth that one dose of emergency contraception will work for your entire cycle. If you have unprotected sex again, you would also need to take an emergency contraceptive pill again to reduce your chances of pregnancy.
What are other options for emergency contraception?
The copper IUD, known in the United States by the brand name Paragard, is the most effective form of emergency contraception, according to the American College of Obstetricians and Gynecologists.
Getting it, though, requires a prescription and a visit to a health care provider to have it inserted, a process which can take longer than the roughly five day window during which it needs to be placed in order to prevent pregnancy after unprotected sex.
A copper IUD can protect against pregnancy for up to 10 years or more. Its efficacy is not affected by weight.
With copper IUDs, “not only are you getting your emergency contraception on board but you’re also getting your longer term method at the same time,” Dr. Edelman said.
Some recent research has also shown that hormonal IUDs can be an effective form of emergency contraception.
Could the morning-after pill become illegal?
It isn’t clear right now. President-elect Donald J. Trump has said alternately that he is open to supporting regulations on contraception and that he does not support a ban on contraception.
But reproductive rights activists say that some states’ actions and legislators’ rhetoric have sparked concerns about future access. “We’ve had a really solid road map over the past couple of years of just how much access to all forms of contraception, including emergency contraception, are under attack,” Dr. Kavanaugh said.
