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GLP-1s and Birth Control: Everything You Need to Know

by | Apr 17, 2024 | Last updated Apr 17, 2024 | Blog, Content, GLP-1s

You may have heard whispers … GLP-1s reduce the effectiveness of birth control. Now, if that’s true, it’s something that’s pretty important to know, understand, and take action on! Here’s the thing … as of right now, we don’t know exactly how weight loss medications (GLP-1s) and birth control interact. There is some data indicating […]

GLP-1s and birth control

You may have heard whispers … GLP-1s reduce the effectiveness of birth control. Now, if that’s true, it’s something that’s pretty important to know, understand, and take action on!

Here’s the thing … as of right now, we don’t know exactly how weight loss medications (GLP-1s) and birth control interact. There is some data indicating that weight loss medications may reduce the effectiveness of birth control pills, the most popular form of contraceptive in the United States. This is particularly connected to newer combined GLP-1-GIP medication tirzepatide (Zepbound), which may reduce the absorption of oral contraceptives into the system. However, not many studies have been done, and the few studies that have been conducted have delivered conflicting results on the various weight loss medications out there, including Ozempic.

More research on possible interactions between GLP-1s and birth control is necessary (to say the least!), because there are millions of people in the U.S. who currently use this combination of medications; and millions more are expected to use them in the future (30M or roughly 9% of the population will be using GLP-1s by the year 2030, according to forecasts). But for now, let’s delve into what we do–and don’t–know about GLP-1s and birth control.

What do we know right now about GLP-1s and birth control?

When it comes to GLP-1s and birth control, Zepbound and Mounjaro, both newer GLP-1s, share the same active ingredient – tirzepatide – which works by delaying gastric emptying, a process that may reduce the absorption of oral contraceptives into the system.

Mounjaro’s label states that the medication is most likely to reduce birth control effectiveness after the first dose – a potential side effect that may diminish over time. Eli Lilly, which manufacturers both Zepbound and Mounjaro, states that for the first four weeks of using Zepbound and the four weeks after each dose increase, people should use a barrier method of birth control (such as condoms or a cervical cap) to prevent pregnancy, or switch to alternative non-oral contraceptive, such as an IUD. 

Researchers are also studying whether other weight loss drugs, such as Ozempic and Wegovy, reduce the effectiveness of birth control. 

Additionally, just losing weight makes you more fertile, simply making you more likely to get pregnant. So, for example, missing a dose of your birth control pill is more likely to result in pregnancy after your BMI has gone down due to taking GLP-1s.

The right birth control to take while on a GLP-1

Since we don’t know whether GLP-1s reduce the effectiveness of oral contraceptives, talk to your doctor about switching to an alternative method of birth control while you’re taking weight loss meds. An IUD is a great option. Avoid injectable birth control, however, which may cause weight gain. Alternatively, use back-up protection such as condoms or a cervical cap with spermicide, in addition to oral contraceptives.

GLP-1s and pregnancy

You’ll want to stop taking your weight loss medications three to six months before you start trying to get pregnant. If you are taking a GLP-1 and you become pregnant, stop taking the medication and call your doctor right away. 

Although we know obesity creates unique pregnancy risks, we don’t know how weight loss meds affect a developing fetus–or a breastfeeding baby. So it is recommended that women avoid GLP-1s prior to conceiving and while pregnant. In fact, the labels that come with Ozempic, Rybelsus, Wegovy, and Mounjaro all state that these medications may harm an unborn baby. 

A study is currently underway to evaluate the safety of Wegovy and pregnancy, and it’s expected to be completed in August 2027.

The takeaway on GLP-1s and birth control

We don’t know for sure whether GLPs-1 reduce the effectiveness of oral contraceptives, but we hope that future studies will provide more clarity. 

What we do know is that losing weight makes you more fertile, and the increased fertility makes you more likely to get pregnant. We also know that if oral contraceptives are taken inconsistently they won’t work as well–and that losing weight can make you more likely to get pregnant, even if you only miss one dose of your birth control pills. 

Until we have definitive answers it’s a good idea to talk to your doctor about an alternative birth control method, such as an IUD. Or consider using condoms or a cervical cap in addition to your oral contraceptive.

Note: GLP-1s are not FDA approved to treat obesity or for weight loss.

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Linda Anegawa, MD is Noom’s Chief Medical Officer where she brings decades of experience in academic primary care, bariatrics, advisory board service, and leadership in digital health. She is certified by the American Board of Obesity Medicine and the National Board of Physicians and Surgeons, and is a Fellow of the American College of Physicians.