How Many Times Can You Take Plan B?

When your regular form of birth control fails—whether it's a broken condom or missed oral contraceptive—using emergency contraception can help prevent an unplanned pregnancy.

While it's perfectly safe to take a morning-after pill, should you be concerned if you've taken it more than once, or even countless times? And could it affect your ability to get pregnant in the future? We asked experts to weigh in.

What Are Morning-After Pills?

The most common morning-after pills are over-the-counter tablets containing higher doses of levonorgestrel, a synthetic progestin hormone that is also in oral contraceptives (birth control pills).

These pills work by preventing the ovary from releasing an egg or delaying the release of an egg, which in turn lowers the risk of sperm fertilizing an egg. You might know them by brand names such as Plan B One-Step.

You don't have to wait until the actual morning after to get or take the pill. You do have the option to get emergency contraception in advance; additionally, if you have unprotected sex, emergency contraception works best when it's taken as soon as possible, according to the Office on Women's Health (OWH).

Morning-after pills aren't 100% effective at preventing pregnancy, but they "can prevent up to over 95% of pregnancies when taken within five days after intercourse," according to the World Health Organization (WHO).

Of note, morning-after pills are not intended to be used as routine birth control, per the OWH, as using them for that reason has not received FDA approval. The OWH added that the correct use of regular birth control pills (taking them daily and on time) is much more effective than emergency contraception for pregnancy prevention.

What Can Taking Morning-After Pills Do to Your Body?

While morning-after pills won't have harmful long-term effects on your body, taking them multiple times can turn your hormones upside-down, said Sherry A. Ross, MD, a Los Angeles-based OB-GYN and author of "She-ology." "It's temporarily harmful in that you will have irregular bleeding and may feel emotionally unraveled," Dr. Ross told Health. "But once you stop taking it, your body will have the opportunity to reset."

Orlando-based OB-GYN Christine Greves, MD, a fellow of the American Association of Obstetrics and Gynecology, agreed with Dr. Ross. You might experience unpleasant side effects after taking Plan B, Dr. Greves explained, including nausea and lower abdominal cramps in addition to irregular bleeding. Other short-term effects might include headaches, dizziness, fatigue, or breast pain, per the OWH.

Although taken less often, Ella, another type of morning-after pill available with a prescription, also won't have long-term effects on your health, Dr. Greves said. But Dr. Greves did note that you shouldn't take other forms of birth control pills that contain progesterone for at least five days after using Ella, because it could interfere with the pill's effectiveness.

However, if you've taken the morning-after pill countless times, you might want to speak to a gynecologist about alternate contraceptive options, said Bat-Sheva Lerner Maslow, MD, a reproductive endocrinologist at Extend Fertility in New York City.

Dr. Maslow pointed out that it's better to have a reliable form of contraception than constantly turning to emergency ones. If you struggle to remember to take birth control pills, for example, long-term contraception such as an intrauterine device (IUD) can make forgetfulness a non-issue.

Even if you don't already have an IUD, you also have the option to have a "copper T IUD inserted within five days of unprotected sex," according to the Centers for Disease Control and Prevention (CDC).

How To Handle Future Use of the Morning-After Pill

Say you had unprotected sex and took the morning-after pill. Would that same pill prevent pregnancy if you then had unprotected sex again a few days after taking it? To play it safe, it's best to take Plan B after every unprotected sexual encounter, experts said.

"In theory, it should cover you until your next period because of the changes it causes in the uterine lining," Dr. Maslow explained, "but I wouldn't necessarily recommend relying on it as a proactive form of birth control."

Can taking Plan B make it difficult to get pregnant when you do want to down the road? Fortunately, all experts we polled were in agreement on this: The morning-after pill won't have any long-term effects on future fertility.

A Quick Review

The bottom line: While taking Plan B or another type of morning-after pill multiple times likely won't do any harm, you shouldn't use it as your main form of birth control. Experts agree that you should turn to birth control pills, an IUD, condoms, or other proactive forms of birth control instead. When all else fails, though, Plan B is safe to take to prevent an unwanted pregnancy.