There is no medical limit on how many times you can take Plan B. You can use it as many times as you need it, including more than once in the same menstrual cycle. The American College of Obstetricians and Gynecologists confirms that oral emergency contraception may be used repeatedly, even within a single cycle. That said, frequent use comes with some practical downsides worth understanding.
No Maximum Number Exists
Plan B contains 1.5 mg of levonorgestrel, a synthetic hormone also found in daily birth control pills (just at a much lower dose). There is no cap set by the FDA or any major medical organization on how many times you can take it in a year or over your lifetime. Each dose works independently by delaying ovulation, so if you have unprotected sex again after taking it, you would need another dose for that new exposure.
The prescription alternative, ella (ulipristal acetate), is a different story. Less is known about using ella multiple times in the same cycle, and if you’ve already taken ella, the most effective backup options are a copper IUD or a hormonal IUD rather than another pill.
Why It’s Not Ideal as a Regular Method
Plan B is safe to repeat, but it’s not as effective as regular birth control. It works best when taken as soon as possible after unprotected sex and only prevents pregnancy from that single encounter. It does nothing to protect you going forward. If you find yourself reaching for it frequently, switching to an ongoing method will give you better pregnancy prevention at a lower cost. A single Plan B pill typically runs $30 to $50, which adds up quickly compared to most monthly or long-acting options.
Using emergency contraception often can also make your periods irregular or unpredictable. That creates a stressful cycle of its own, since a late period after taking Plan B can be hard to interpret. Is it a side effect or a sign of pregnancy? The general guidance is to take a pregnancy test if your period is more than a week late after using Plan B.
Side Effects With Repeat Use
Common side effects from a single dose include headache, nausea, dizziness, and breast tenderness. These are usually mild and resolve within a day or two. Plan B can also cause spotting between periods or make your next period heavier than usual. It may delay your period by up to a week.
Taking Plan B multiple times doesn’t introduce new or more dangerous side effects, but the cycle disruption tends to stack. Repeated doses in a short window can make it genuinely difficult to track where you are in your menstrual cycle, which ironically makes it harder to know when you’re at risk of pregnancy in the first place.
It Does Not Affect Future Fertility
Repeated use of Plan B does not reduce your ability to get pregnant later. Planned Parenthood states clearly that using emergency contraception more than once does not affect fertility and will not prevent someone from becoming pregnant in the future. The hormone clears your system quickly, and there is no cumulative effect on your reproductive health.
Starting Regular Contraception After Plan B
If you’ve just taken Plan B and want to start a regular birth control method, you can begin most hormonal options immediately. That includes the pill, the implant, the patch, or the shot. There’s no required waiting period after levonorgestrel-based emergency contraception. If you took ella instead, you need to wait five days before starting hormonal birth control, because the two can interfere with each other.
A copper IUD is worth knowing about for two reasons: it’s the most effective form of emergency contraception when placed within five days of unprotected sex, and it doubles as long-term birth control for up to 10 years. If you’re in a situation where you’re using Plan B repeatedly, asking a provider about an IUD or implant can solve the problem in a single visit.