Can you take Plan B on birth control?
Very few of us, if any, will get through life without encountering one of those urgent, OMG moments. Of course, this extends to those times when a condom breaks or you get caught up in a romance-novel moment—or any other circumstance, really, that may lead to an unplanned pregnancy.
Plan B was designed specifically for these times. So then how long does Plan B stay in your system and how effective is it? The emergency contraceptive (or EC, as we like to call them) can reduce the chance of pregnancy by 75 to 89% if it’s taken within 72 hours of an unprotected sexual encounter. Despite Plan B’s safety, efficacy, and overall transparency, questions about ECs can come with a bunch of questions, including:
Can I take Plan B if I’m already on birth control? And does Plan B affect birth control?
The short answer: Yes to the first question, and no to the second.
Plan B 101
Plan B is the brand name of levonorgestrel, a class of progestin medications that have been used in several forms of oral contraceptives for several decades. Progestin, in short, mimics progesterone–a hormone you naturally produce that’s key to ovulation. With Plan B, much higher doses of progestins are employed to prevent an unintentional pregnancy.
Plan B is a one-and-done pill intended to prevent an unplanned pregnancy when other birth control methods don’t work.
However, if you’re on the birth control pill, you can still take Plan B when you need it.
Rather, Plan B emergency contraception pill is used (yes, even by those who are on oral contraceptives) when:
You missed a single or more dose of your oral contraceptive. The chances of getting pregnant after a single missed dose are low; however, it increases with each missed pill.
You missed going in for your Depo shot (or another contraceptive injection).
The condom you were using broke, slipped off, or, you just happened to notice post-coital, was wayyyyy past its expiration date. (Yep, this happens–and more often than you might think.)
You forgot your diaphragm or other form of birth control at home or misplaced it.
You miscalculated your window of ovulation.
(This is by no means an exhaustive list, but it ought to give you an idea of why and when Plan B replaces, well, Plan A.)
Read on to gain a better understanding of Plan B, how it interacts with oral contraceptives, and alternative forms of emergency contraceptives for those OMG moments.
Does Plan B interact with birth control?
Plan B and oral contraceptives have a similar mechanism of action: They inhibit or delay ovulation.
As we mentioned, Plan B emergency contraceptive pill works by flooding the body with a much higher amount of progestin than what’s found in birth control pills to either:
Prevent the release of an egg
Thicken the cervix to obstruct the passage of sperm and hinder fertilization
Halt implantation by thinning the uterine wall
If you’re consistent with your birth control pills—taking them daily, and roughly at the same time—it isn’t necessary to take Plan B unless you’ve missed a dose or more of your regular oral contraceptives.
At the same time, Plan B doesn’t impact the effectiveness of your birth control pills, or vice versa.
In other words, one doesn’t cancel the other out.
After taking Plan B, you should resume your birth control pills right away. You may also want to use an additional form of birth control, such as condoms, to ward off an unintentional pregnancy until you’re back in the swing of taking your oral contraceptives routinely or until you’ve taken your birth control pill for seven consecutive days.
However, if, after unprotected sex, you called upon ella–a prescription-only antiprogestin form of emergency contraception we’ll discuss later on in this article–keep in mind that the CDC recommends waiting five days to resume taking your birth control.
A few words of caution
It’s vital to note here that, while there are no restrictions on how often you can take Plan B EC pills, it shouldn’t be used as your primary form of birth control. It was created to prevent pregnancies after a single act of unprotected sex. That’s why it gained its status as an emergency contraceptive.
What’s more, oral contraceptives are 99% effective at preventing pregnancy, while Plan B is 95% effective when taken in the first 24 hours of unprotected sex—and that percentage goes down the longer you wait to take it.
Other medications that can affect the effectiveness of Plan B
While Plan B emergency contraception pill has a proven track record of effectiveness, certain medications and herbal supplements can impact its efficacy by reducing the level of progestin in your body, among other interactions. These include:
Drugs used to treat HIV, including Nevirapine and Nelfinavir
Antibiotics typically prescribed to treat tuberculosis, such as Rifampin and Rifabutin
Anti-seizure medications, including barbiturates, Phenytoin, and Primidone
Antifungal medications, such as Griseofulvin
If you’re wondering if that old wives’ tale that antibiotics destroy birth control’s effectiveness is true, the answer is a resounding no.
Planned Parenthood confirms that antibiotics used to treat TB (those mentioned above) are the only ones that mess with your oral contraceptives.
Risk factors to keep in mind while taking Plan B
By and large, the Plan B pill is safe for most people who menstruate. In fact, there are no documented reports of serious risk factors or side effects of Plan B.
That said, we do know of two factors that may be either deleterious to your health or might impact Plan B’s effectiveness:
Allergies– Before taking Plan B, be sure to discuss your allergies with your pharmacist or healthcare professional. If you’re allergic to any of the ingredients in Plan B, they may steer you in another direction.
Weight– A great deal of controversy has surrounded Plan B’s effectiveness when used by those who have a high BMI. While we stand with the FDA’s insistence that emergency contraceptives are a viable option for people who menstruate no matter their weight, we would be remiss without bringing it up here.
Additionally, while Plan B will not interrupt the effectiveness of your birth control pills once you resume taking them, it’s important to keep in mind that the Plan B pill and many oral contraceptives have a powerful ingredient in common—progestin (specifically levonorgestrel). Meaning, if you experience side effects from your birth control that contains this progestin (and manydo), you may have side effects with Plan B as well.
Abdominal pain and cramping
Irregular vaginal bleeding
Rest assured these side effects tend to dissipate after the first week of taking Plan B, and, according to the Mayo Clinic, generally fade within a few days. It's still recommended to stay alert about these side effects as they can be similar to the signs that Plan B didn't work in some instances.
Plan B alternatives
Plan B may be the most well-known emergency contraceptive available (such a catchy, apt name, wouldn’t you agree?), but it certainly isn’t your only option.
ella – As we noted above, ella is what’s known as an antiprogestin, in that it doesn’t contain hormones like Plan B. Deemed the most effective form of emergency contraception after 72 hours (and up to 120 hours) of having unprotected sex, it’s 85% effective at reducing the chance of pregnancy. That said, unlike Plan B, which is an over-the-counter medication, ella requires a prescription.
As we also mentioned above, you must refrain from resuming your oral contraceptive regime for five days after you’ve taken ella. Why? In sum: They reduce the efficacy of each other.
Copper IUD – ParaGard, as you might know it as, is an intrauterine, non-hormonal copper T that, once inserted into the uterus, creates a toxic environment for sperm and thwarts fertilization. Statistics reveal that it’s 99% effective at preventing pregnancy, rendering it one of the leading choices overall for contraception.
Know in advance, though, that copper IUDs may be unsafe for those who have pelvic inflammatory disease, uterine fibroids, Wilson’s disease, and other health issues–all risk factors you can, of course, discuss with your medical professional.
Generic forms of Plan B – These include Option 2, One Dose, Take Action, My Way, and My Choice.
Find peace of mind with Favor
Plan B is precisely as its name suggests—plan B. It’s a fallback method to prevent the potential of a pregnancy if you practiced unguarded intercourse or your usual form of birth control was somehow…interrupted. (No shame there: We’re all human.)
In no way should Plan B replace your usual method of birth control, but it also doesn’t interfere with the effectiveness of your regular birth control pills, either. You may experience similar effects to those you had when you began taking oral contraceptives—side effects that, almost ironically, mirror the signs of pregnancy. However, because of the short amount of time Plan B stays in your system, they ought to dwindle within a few days.
But most of all? Plan B is safe, effective, and economical–and it doesn’t affect birth control. A win-win, we might very well say–and not an emergency in the least if, with Favor, you always have it within reach.
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