The Most Common Side Effects of Plan B, According to MDs

Taking emergency contraception is intimidating. It's called Plan B for a reason — it's not something that was supposed to be on your radar, and being hit with an unexpected obstacle is never easy. Luckily, modern medicine gives us the chance to overcome that sudden hiccup. Whether you had unprotected sex, missed a birth control pill, were sexually assaulted, or your method of birth control failed, you have the option to take emergency contraception within a few days. (Plan B One-Step or its generics should be taken less than 72 hours after unprotected sex, and Ella should be taken less than 120 hours, or five days, after unprotected sex.)

And while it's possible you'll face a few unpleasant side effects from taking Plan B or another type of emergency contraception, the benefits of the medication likely outweigh a nagging headache or upset stomach. In fact, experts say unwanted side effects don't commonly accompany the pill, and if they do, there's usually nothing to worry about.

Still, everyone is different, and though there's no way to predict exactly how your body will react to emergency contraception, you can put your mind at ease by knowing what's normal. Keep reading to learn about the most common side effects of Plan B, according to doctors, and everything else you should know before taking it — including, for example, whether or not you can take ibuprofen with Plan B.

The most common side effects of Plan B One-Step, Ella, or generic versions of emergency contraception are nausea, vomiting, headache, painful menstruation, cramps, dizziness, breast tenderness, and irregular bleeding, according to the Mayo Clinic.

Though it's possible the pill will leave you feeling sick, it isn't very common, Sophia Yen, MD, MPH, co-founder of Pandia Health, tells POPSUGAR. Prudence Hall, MD, founder and medical director of The Hall Center, agrees. Both doctors say that, in their own experience, most of their patients haven't felt ill after taking emergency contraception. "They have maybe very mild symptoms, maybe a little bit of fatigue, but they feel OK," Hall says.

One study on the side effects of emergency contraception found that, among people who took levonorgestrel (the drug found in Plan B One-Step and its generics), 23 percent experienced nausea, 18 percent experienced abdominal pain, 17 percent experienced fatigue or headache, and only 6 percent experienced vomiting. And, FWIW, 58 percent of people who took emergency contraception got their period within a few days of the day they expected it to come, according to their cycle.

If you do fall into the category of people who face these possible unpleasant side effects, Yen says there's no need to worry. "The beautiful thing about Plan B is it's over-the-counter," she says. "We wouldn't let anything go over the counter if it could do something horrible to you." People who are prone to headaches, nausea, and other possible side effects of Plan B are more likely to experience them after taking the medication, Yen adds.

If you experience irregular bleeding as a side effect of taking emergency contraception, don't stress. "A lot of people worry if they have spotting or bleeding after they take it that there's something wrong, but that's actually normal," Hall says. If you don't get your period within three to four weeks of taking the morning-after pill, however, you should take a pregnancy test, according to the Mayo Clinic, because you could be pregnant.

If you have bleeding or spotting that lasts longer than a week or you develop severe lower abdominal pain three to five weeks after taking the morning-after pill, you should contact your doctor, according to the Mayo Clinic. These can indicate a miscarriage or that you may be experiencing an ectopic pregnancy.

Since emergency contraception can cause cramping, many people wonder if it's OK to take ibuprofen with Plan B. Good news: It's perfectly safe to take Advil (aka ibuprofen), Tylenol (acetaminophen), aspirin, or other pain killers to decrease any discomfort you feel after taking emergency contraception, Yen says.

However, if you vomit within one hour after taking the medication, it's important that you take it again, she adds. When taking the pill a second time, Yen recommends taking diphenhydramine, or Benadryl, immediately after to fight nausea.

Yen has another recommendation to prevent yourself from vomiting up the pill: "The other alternative that most people don't know is that you can take the pill via your vagina . . . It may decrease nausea and vomiting, but the more important thing is even if you get nausea and vomiting, you can't vomit up the medicine, so that at least the medicine will work." That said, it's crucial that you talk to your doctor before trying this strategy, to make sure that it's appropriate for your situation and that you're taking a correct dose; you don't want to experiment with your health, especially when trying to prevent an unplanned pregnancy.

With Plan B and its generics, you can go ahead and keep taking your hormonal birth control pills, Yen says. However, if you're taking Ella, you need to wait five days before resuming your birth control pill usage. "Ella is an anti-progesterone, so if you throw on [i.e. take] progesterone, which is in all birth control pills, the patch, the ring, and IUDs with hormones, you defeat the whole point of your emergency contraception," she explains.

That said, if you're consistently taking your birth control pills, there's no need for emergency contraception, Hall says. "As long as you're on the birth control pill, it's better than Plan B," she says. But if you've missed a few days or haven't been constant with your doses, she recommends taking Plan B, Ella, or generic versions, if needed.

Using emergency contraception repeatedly can result in increased side effects, such as irregular bleeding, although using multiple times poses no known health risks, according to the World Health Organization. "You can take emergency contraception as many times as you need to," Yen says, "but the reason we don't recommend it is because it's jarring on your system." When you take the medication, you're essentially telling your body it's pregnant in order to prevent ovulation, Yen explains. Since your body thinks it's already pregnant, it won't waste time and energy releasing any eggs, causing you to later have a period and "reset your clock," she added.

"[Emergency contraception] has no long-term side effects, no effect on your fertility, and no effect if you are already pregnant," Yen says. (That's right: This is not the same as the abortion pill.)

The only reason you might want to avoid emergency contraception is if it makes you feel extremely ill to the point of being unable to go about your normal life, Hall says. Otherwise, rest assured that you will be OK. If you find yourself taking emergency contraception often, consider talking to your doctor about a form of contraception that might work better for you.

—Additional reporting by Lauren Mazzo