While Mounjaro is generally safe for most people, there’s some things you should bear in mind while using it. Like, for instance, that it might interact with other medicines—including your birth control pills.
Don’t worry, you can still protect against pregnancy while taking Mounjaro. But if you’re on the pill, you might need to take some extra precautions. We’ve explained everything you need to know about Mounjaro and contraception below.
How Mounjaro works in the body?
Before we get into it, let’s take a quick look at how Mounjaro works.
Mounjaro weight loss injections make you feel full, so you eat less. They do that by acting like two of the body’s natural hunger hormones, GLP-1 and GIP, to slow down your digestion and keep cravings at bay.
Can Mounjaro make my oral contraception less effective?
It might. Mounjaro slows down how your stomach empties, which can affect how well ooral medicines, like HRT and birth control pills, can be absorbed by your body. That means the pill might not work as reliably—especially when you're just starting Mounjaro or increasing your dose.
Because of this, it’s recommended to use a barrier method like condoms for the first four weeks after starting Mounjaro, and again for four weeks after each dose increase. Since Mounjaro is taken weekly and the dose can go up every month, some people might need to use condoms for longer stretches.
If you stay on the same dose for more than four weeks (like staying on 5 mg for two months), you don’t need extra protection beyond that initial four-week window—unless you increase the dose again.
So, to keep things simple and reliable, it might be easier to switch to a non-oral contraceptive like the coil, implant, or injection during treatment. Your GP can help you figure out the best option for you.
By the way: Mounjaro isn’t recommended if you’re pregnant or breastfeeding.
Vomiting, diarrhoea, and birth control pills
Mounjaro can also bring on side effects like nausea, being sick, or diarrhoea. These may affect over one in ten people on the medicine—and they might also prevent your birth control pills from being fully absorbed.
If you’re sick less than 3 hours after taking the combined pill, or up to 4 hours if you’re on Qlaira or Zoely, take your next pill asap. You can then take the next one at your usual time. But if your symptoms carry on after that, use another type of contraceptive as well as the pill until you’ve taken the pill for a week without being sick.
The same goes for diarrhoea. If you have it for over 24 hours, keep taking your pill as normal but use another contraceptive until your symptoms have been gone for a week.
What are your contraception options while using Mounjaro?
We’re glad you asked! If you’re taking Mounjaro and the pill, and you’re sexually active, you must use a barrier method (such as condoms) alongside your oral contraception for the first four weeks after starting Mounjaro or after each time your dose is increased.
Alternatively, you could switch to another method that isn’t taken as a pill, like the Mirena or copper coils, or the contraceptive patch. Your provider can walk you through your options and help you decide which is best.
Is Mounjaro right for you?
Not everyone should take Mounjaro. For example, it’s not recommended if you’re planning to get pregnant, are breastfeeding, or have ever had thyroid cancer. But if it is suitable for you, it can be a gamechanger.
Weight loss medication can be a great option if you’ve tried to lose weight another way but didn’t get the results you hoped for. Clinical research shows that people who take the injections lose up to 22.5% of their starting weight.
And we’re here to help you reach your goals. Through our weight loss programme, you’ll get medicine posted to you each month plus personalised support from our team of coaches and clinicians. We’ll be right there with you, cheering you on at every step of your journey.
Take our quiz to see if you’re eligible for the programme. Our clinicians will come back to you within minutes.
¹
