Does Wegovy Affect Birth Control Pills?

Wegovy works by mimicking a hormone called glucagon-like peptide-1 (GLP-1), which plays a key role in appetite regulation. It slows down your digestion and reduces your appetite, so you feel fuller quicker and for longer.

So if you’re using Wegovy (semaglutide), you might wonder if this also affects your oral hormonal contraceptive pill. 

To help put your mind at rest, we break down the evidence on Wegovy’s effect on the contraceptive pill. And if you’re experiencing side effects like vomiting and diarrhoea, we explain when you might want to consider extra – or alternative – protection.

Can Wegovy Affect the Contraceptive Pill?

No. There is currently no evidence that semaglutide, the main ingredient in both Ozempic and Wegovy, interacts with the oral contraceptive pill. This means Wegovy itself does not change how the pills work in the body or make it less effective.

This is unlike Mounjaro (tirzepatide), another type of GLP-1 weight management medication. The UK’s medicines regulator (MHRA) recently warned that “Mounjaro may reduce the effectiveness of oral contraceptives in those who are overweight.”

Experts don’t know why Mounjaro makes the pill less effective. But it works slightly differently than Wegovy and other weight loss injections, including Saxenda. Wegovy, Saxenda and Mounjaro all mimic the hormone GLP-1 and delay gastric emptying. However, Mounjaro also mimics a second hormone, called gastric inhibitory polypeptide (GIP).

Do Vomiting and Diarrhoea Make the Contraceptive Pill Less Effective?

Yes. While Wegovy itself doesn’t affect the contraceptive pill, gastrointestinal (stomach-related) side effects like vomiting or diarrhoea can.

If you vomit within two to four hours of taking your pill, it can prevent your body from absorbing the hormones. So you’ll need to treat it as a missed pill. If you’re experiencing diarrhoea for longer than 24 hours, use extra protection, such as condoms.

Be especially cautious during the first few weeks of treatment or after a dose increase. This is when these side effects are more likely.

Should I Switch to a Different Contraceptive?

You don’t have to switch to a different contraceptive if you’re using Wegovy weight loss injections and taking oral contraceptives. But if you stay on the pill, consider using condoms during periods of vomiting or diarrhoea.

If you’re regularly feeling unwell, you might want a more dependable form of contraception. If you’re taking oral contraceptives, it might make sense to change to a non-oral method. The following methods are not affected by vomiting and diarrhoea:

• Hormonal IUD (e.g. Mirena, Jaydess, Kyleena)
• Copper IUD (non-hormonal birth control)
• Contraceptive implant (e.g. Nexplanon)
• Injection (e.g. Depo-Provera or Sayana Press)
• Vaginal ring or patch

Can I Use Emergency Contraception on Wegovy?

Yes, you can use emergency contraception while taking Wegovy. The Faculty of Sexual and Reproductive Healthcare (FSRH) has said there is no direct evidence that GLP-1 receptor agonists reduce the effectiveness of emergency contraception.

It’s still important to choose the most reliable option to prevent pregnancy. Some options are more effective than others and your weight can affect how well they work. 

Types of emergency contraception include:

• The Copper IUD: The copper coil (IUD) is the most effective method of emergency contraception. Your weight, vomiting or GLP-1 medicines won’t affect it. It can also be left in as long-term contraception.

• Levonorgestrel pill (LNG-EC): It’s also known as the morning-after pill and has the brand name Levonelle. It may be less effective if you weigh over 70 kg or have a BMI over 26. In these cases, the FSRH recommends taking a double dose.

• Ulipristal acetate (ellaOne): This option may work better if your weight is higher. But it does interfere with hormonal contraception. You’ll need to wait five days before restarting your pill and use condoms during that time.

If you vomit within three hours of taking an emergency pill, your body may not fully absorb it. Contact a pharmacist, GP or sexual health clinic. You may need a repeat dose or another method.

Can I Get Pregnant While on Wegovy?

If you don’t use contraceptives or the contraceptive you’re using fails, you could get pregnant on Wegovy. While semaglutide doesn’t directly affect your fertility, being overweight or obese can reduce fertility. So your fertility may increase if you lose weight while using weight loss drugs.

However, you should not take Wegovy or any other GLP-1 treatment during pregnancy. You also shouldn’t use them while trying to get pregnant or while breastfeeding. 

This is because there currently isn’t enough information on whether it could harm the baby or increase risks like pregnancy loss. Some animal studies have shown potential harm to the developing baby.

The MHRA advises anyone “who gets pregnant while using them should speak to their healthcare professional and stop the medicine as soon as possible.”

If you’re trying to get pregnant, stop using semaglutide at least two months before trying for a baby. The drug stays in your body for between five and seven weeks after your last injection. Tell your healthcare provider before stopping the medication.

When to Seek Support

Speak to a doctor, pharmacist or sexual health nurse if:

• You’ve vomited after taking the pill and aren’t sure what to do
• You’re experiencing regular or severe diarrhoea
• You’re worried your contraception might not be working
• You’re thinking about getting pregnant
• You think you might already be pregnant

If you’re a patient with Simple, remember we’re here for you throughout your weight loss journey. If you have any concerns about using contraceptives on Wegovy, call us on 0141 774 5023.

 

Key Takeaways

• Wegovy and Contraception: There’s no evidence that Wegovy affects oral contraceptives This makes it different from Mounjaro, which interacts with oral contraceptives. Both are types of drugs called GLP-1 receptor agonists. But Mounjaro works slightly differently.

• Watch for Side Effects. Vomiting or diarrhoea can affect how well the pill is absorbed. Use condoms alongside the pill during these times to stay protected. If you’re concerned about missed pills or absorption, consider longer-term options like the implant, coil or injection.

• Choose the Right Emergency Contraception. The copper coil is the most effective emergency option. Your weight, vomiting and GLP-1 medications won’t affect it. If using levonorgestrel, you may need a double dose if you weigh over 70kg.

• Plan for Pregnancy. Stop Wegovy two months before trying to conceive. Speak to a healthcare professional for personalised advice.

• Ask for Help: Not sure if your contraception is working as it should? Issues with your weight loss medication? Speak to your GP, pharmacist or sexual health clinic. They can guide you on the safest options.

References 

European Medicines Agency (EMA). (2024). Ozempic: EU Summary of Product Characteristics (SmPC). [online] Available at: https://www.ema.europa.eu/en/documents/product-information/ozempic-epar-product-information_en.pdf [Accessed 10 June. 2025]

Faculty of Sexual and Reproductive Healthcare (FSRH). (2024). Clinical Effectiveness Unit Statement: GLP-1 agonists and contraception. [online] Available at: https://fsrh.org/Common/Uploaded%20files/documents/CEU-statement-GLP-1-agonists-and-contraception.pdf [Accessed 10 June. 2025]

Muller, D.R.P., Stenvers, D.J., Malekzadeh, A., Holleman, F., Painter, R.C., Siegelaar, S.E., 2023. Effects of GLP-1 agonists and SGLT2 inhibitors during pregnancy and lactation on offspring outcomes: a systematic review of the evidence. Frontiers in Endocrinology (Lausanne) [online]. 14, Article 1215356. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC10597691/

Authorship