The Office on Women’s Health (OWH) recommends the following guidelines for optimal effectiveness: Take Plan B One-Step or a generic version of Plan B as soon as possible, within three days (72 hours) after unprotected sex. For the two-dose generic version of Plan B, which is called Next Choice, take one pill ASAP within three days and the second pill 12 hours afterward.
It’s important to note that emergency contraception is intended to protect against pregnancy after a single act of penetrative penis-in-vagina sex. That means if you have unprotected sex, take Plan B, and then have unprotected sex again, you will need to take Plan B again.
Does Plan B have side effects?
Plan B and other emergency contraceptive pills are safe ways to prevent pregnancy. “The progesterone-like hormone in these pills is something we’ve used for a long time, and when people have studied what happens in individuals who use several repeat doses, it’s been shown to be safe,” Jessica W. Kiley, MD, MPH, an associate professor of obstetrics and gynecology at Northwestern University’s Feinberg School of Medicine, tells SELF.
The potential short-term side effects associated with Plan B usually aren’t any more serious than you might experience during PMS or a stomach bug. Per the OWH, some people may experience headaches, abdominal pain, fatigue, dizziness, nausea, or breast pain. Plan B can also affect the timing of your next period. And, according to Planned Parenthood, “there have been no reports of serious problems out of the millions of people who’ve taken it.”
How do I know if Plan B worked?
Some spotting can happen after you take an emergency contraceptive pill, and your next period may be irregular. The timing of your next period after taking emergency contraception varies. Andrea Henkel, MD, an obstetrics and gynecology physician at Stanford Children’s Health, tells SELF it’s normal to get your period a bit earlier or later after you take emergency contraception, and that your period may be longer or shorter than normal. “With either, if you are more than a week late, you should take a pregnancy test, because this much of a delay may represent an early pregnancy,” Dr. Henkel says.
Can I take Plan B if I take birth control pills?
The short answer: yes. Many people use Plan B and other emergency contraception pills as backup forms of protection if they forget to take their daily pill—but you don’t need to double up. “If using your method as prescribed, there is no need to take emergency contraception as a ‘back up,’” Dr. Henkel says. (If you’re on birth control pills and forgot to take them consistently, it might be time to consider a long-acting reversible contraceptive method instead, like the birth control implant or an IUD.)
You can also continue using your preferred method of birth control as prescribed after using Plan B. (If you are using Ella, the prescription morning-after pill, then Dr. Henkel advises waiting five days prior to restarting a hormonal contraceptive method, like combination birth control pills, as they may interact with the emergency contraception.)
Will Plan B make it hard for me to get pregnant later on?
Some people worry that taking Plan B will decrease their chances of getting pregnant intentionally later on, but never fear: Before you google “can Plan B make you infertile,” the answer is definitely not. According to the World Health Organization, “Drugs used for emergency contraception do not harm future fertility,” and there’s also no delay in returning to fertility after using Plan B.
So take heart: There’s no need to panic if you’re facing the prospect of unintended pregnancy. Plan B or other emergency contraceptives are safe and effective—and can help you handle what happens next.