Can you take Mounjaro while breastfeeding? Here is what you need to know

If you’re breastfeeding and considering Mounjaro, it’s natural to wonder how safe it is for you and your baby. The reality is, Mounjaro is a relatively new medication, and as you'll soon find out, research on its effects during breastfeeding is still limited.

In this article, we break down what we do know, what the current evidence suggests, and what to consider before making a decision.

Whether you’re already on Mounjaro or just weighing up your options, understanding the facts can help you navigate this important choice with confidence.

What is Mounjaro?

Containing the active ingredient tirzepatide, Mounjaro is a dual-action weight loss medication, delivered by subcutaneous injection once a week.

It mimics GIP and GLP-1 hormones, both of which work to reduce cravings and help you feel fuller for longer. By doing so, Mounjaro can help decrease appetite, improve blood glucose levels, and influence the pathways that lead to fat loss.

The result? An average weight loss of up to 20% in just 12 months, making Mounjaro the most effective weight loss treatment currently available [1].

Can you breastfeed on Mounjaro?

Research on the use of Mounjaro, breastfeeding, and pregnancy in general is still sparse. We'll dive into what we know in just a bit, but at this stage, the answer to "Can you breastfeed on Mounjaro?" is: it's not recommended.

Healthcare providers generally advise against it, and this goes back to the lack of data around the topic.

Researchers aren't quite sure if Mounjaro can transfer into breast milk in significant amounts, whether a breastfed infant can absorb it, and, if so, what effects it may have.

It's best to err on the side of caution, and the medication itself comes with a precautionary note advising against the use of Mounjaro while breastfeeding [2].

How long does Mounjaro stay in your system?

Mounjaro typically stays in your system for 25-30 days [3], although exact timelines vary from person to person, depending on factors like your age, metabolism, and kidney function, as well as the dosage you're on and how long you've been on Mounjaro.

If you’re planning to get pregnant—or are already pregnant and looking ahead to breastfeeding—make sure to talk to your doctor.

They can guide you as you discontinue the medication and, once the right time comes, help you get back on it safely.

Limited research on GLP-1 medications and breastfeeding

Since Mounjaro is a relatively new medication, research studies on its potential effects on new mums and breastfed infants are still limited and emerging.

Here's what the evidence suggests so far [4]:

• Tirzepatide is a large molecule, so it's improbable that it can transfer into breast milk in significant amounts.
• Even if it does, it likely breaks down in the infant’s gastrointestinal tract. It has a very low oral bioavailability, making absorption unlikely (except in premature infants).
• There are no clinical studies that specifically measure tirzepatide levels in human milk or its effects on babies.

The truth is, we’ll need more research to be able to answer important questions like this.

Until we have it, the best course of action is to work closely with your healthcare providers to understand what being on Mounjaro could mean for you and your baby, and whether it is time to take a break.

This is where personalised, ongoing support—like what Juniper offers—can make all the difference.

With our Weight Reset Programme, you can access the latest weight loss medication, as well as unlimited follow-ups with your prescribers.

Whether you’re navigating life changes or planning for pregnancy, our team of clinicians and health coaches is here to answer all your breastfeeding questions and support you on your weight loss journey, every step of the way.

Making an evidence-based decision

At the end of that day, whether or not you take Mounjaro while breastfeeding is up to you and your doctor.

They can help you make an informed decision based on factors like the age of your baby, the volume of breast milk they drink per day, and your need for treatment [5].

Guidelines for using weight loss injections while breastfeeding

If you choose to take Mounjaro while breastfeeding, make sure to:

• Monitor your baby for any unusual symptoms
• Stay in regular touch with your provider

Alternatives to Mounjaro while breastfeeding

If you're managing type 2 diabetes, your doctor will likely recommend an alternative treatment, such as insulin or metformin, before you start breastfeeding.

These options are better studied for safety during breastfeeding and are effective at managing pregnancy and glucose levels [6][7].

Plus, both help improve blood sugar control without harming the baby, making them preferred choices during this time.

If, on the other hand, you're considering Mounjaro for weight management, your best bet is to focus on lifestyle changes and adopt habits like:

• Giving your body the nutrients it needs to recover during postpartum by eating a diet rich in protein, vegetables, whole grains, fruits, nuts, and seeds.
• Engaging in gentle exercise (emphasis on gentle) like yoga, swimming, or even just walking. Remember that your body is still healing, so you don't want to push it too hard.

Most importantly, avoid losing weight too quickly during the postpartum period. Although your body may have changed—and that can be hard to get used to—this is a time to be kind to yourself and focus on healing, rest, and nourishment.

When your healthcare provider gives you the green light, you can start (or restart) your Mounjaro journey and take a steadier approach to reaching your weight loss goals.

Is Mounjaro safe during pregnancy?

Research is limited, but Mounjaro is generally not recommended during pregnancy.

Animal studies have shown potential pregnancy complications and adverse effects on foetal development, including reduced foetal growth, low birth weight, certain birth defects, and a higher risk of miscarriage [8].

Does Mounjaro affect fertility?

Data is, once again, limited. The only study that exists was performed on male animals. And while there were no changes in male fertility reported, this doesn’t provide much clarity for women, and it’s far from conclusive.

Having said that, we know that the link between weight and fertility is complex and can vary significantly from person to person.

Being overweight (and dealing with related complications like elevated blood glucose and hormonal imbalances) can impact your ability to conceive. So, by promoting weight loss and improving metabolic health, a treatment like Mounjaro can indirectly improve fertility outcomes.

It's also worth mentioning that tirzepatide can change the way your body absorbs the birth control pill, particularly during the first 4 weeks.

That's why the product label recommends women using oral contraceptives switch to a non-oral birth control method or barrier method to prevent pregnancy when initiating treatment.

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