Switching From Ozempic^® to Mounjaro^®

Reviewed by Claudia Berty, MBChB MRCGP DFSRH PGDipENT

Written by Our Editorial Team

Key takeaways:

• Switching from Ozempic® to Mounjaro® should be done under the guidance of your GP or a private medical provider.

• Both weekly injections support type 2 diabetes and weight management, but they have different active ingredients.

• Your provider may start you on a low dose of Mounjaro® and increase it gradually, regardless of your previous Ozempic® dose.

• Shortages have affected both drugs, so availability may impact whether switching is possible through the NHS or private care.

If you’ve been on Ozempic® (semaglutide) but are considering a change, you might wonder if switching to Mounjaro® (tirzepatide) could offer better results.

Maybe you haven’t met your weight loss goals, your blood sugar levels are still not where they should be, or you’re struggling with Ozempic® side effects. In some cases, switching from semaglutide to tirzepatide might help you get out of a weight loss plateau.

Whatever your reason, here’s everything to know about making the switch, including doses, side effects, clinical trials, National Health Service (NHS) guidance, and what to expect during the transition.

Can You Switch From Ozempic® to Mounjaro® in the U.K.?

Yes, you can switch from Ozempic® to Mounjaro®. But changing medicines must be done under medical supervision.

Your general practitioner (GP) or private healthcare provider will look at your:

• Medical conditions, like obesity, type 2 diabetes, high blood pressure (hypertension), or heart disease

• Response to your current medication

• Side effects experienced so far

• Overall weight loss treatment plan and goals

Never take both medications at the same time. While they work slightly differently, they have similar effects, and doubling up can increase safety risks without boosting effectiveness.

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What to Know Before Switching from Ozempic® to Mounjaro®

Ozempic® and Mounjaro® are both glucagon-like peptide-1 receptor agonists, also known as GLP-1 receptor agonists.

Although they belong to the same family of injectable weight loss treatments, there are important differences:

• Class. Both are GLP-1 receptor agonists. But Mounjaro® is also a glucose-dependent insulinotropic polypeptide (GIP) receptor agonist. This dual action is one reason clinical trials suggest Mounjaro® may have more substantial weight loss effects.

• Active ingredient. Ozempic® contains semaglutide, and Mounjaro® contains tirzepatide.

• Approved uses in the United Kingdom. Ozempic® is licensed for type 2 diabetes in the U.K. Mounjaro® is licensed for type 2 diabetes and has also been approved for weight management in people with weight-related conditions.

• Off-license use. Through private care, some people may be prescribed these drugs off-license for weight management outside official NHS criteria.

• Administration. Both are weekly weight loss injections delivered via pre-filled pens.

• Price. Ozempic® and Mounjaro® are priced differently. The cost is subject to change, so it’s hard to say which is cheaper.

• NHS availability. Wegovy®, Ozempic®, and Mounjaro® are available on the NHS under strict eligibility rules. Supply issues can also make accessing them harder.

Both semaglutide and tirzepatide may support weight loss, improve blood sugar levels, and reduce the risk of heart disease. There’s some evidence that tirzepatide might be more effective for weight loss.

Ozempic® vs. Mounjaro® Comparison Chart

Mounjaro® vs. Ozempic®: Which Is More Effective?

Head-to-head clinical trials suggest Mounjaro® may be more effective than Ozempic® for blood sugar control and weight loss results.

Here’s what the research says:

• A cohort study looked at adults with overweight or obesity. It concluded that tirzepatide results in significantly greater weight loss than semaglutide.

• A 2021 study compared semaglutide and tirzepatide. It found that tirzepatide reduced HbA1c (glycated haemoglobin, a marker of average blood sugar levels) more significantly.

• In the 2021 study, participants also lost more body weight on Mounjaro® than Ozempic®.

• A 2024 study sponsored by Eli Lilly looked at people who switched from semaglutide or dulaglutide to tirzepatide. These patients had better HbA1c control and reached their body weight targets on their new medication.  

Still, how well each weight loss drug works varies from person to person. Your response to either medicine can depend on your treatment plan, body mass index (BMI), and other health conditions you have.

How to Switch From Ozempic® to Mounjaro®

When switching medications, most medical providers recommend starting Mounjaro® the week after your last Ozempic® injection.

Ozempic® to Mounjaro® Dosing Schedule

Even if you were on a higher dose of Ozempic®, your provider will likely start you on the lowest dose of Mounjaro® — a 2.5-mg (milligram) weekly injection.

Here’s how the dosing schedules usually work with Ozempic® and Mounjaro®:

• Ozempic®. Ozempic® typically starts at 0.25 mg. The dose generally increases every four weeks, up to a maximum dose of 2 mg weekly.

• Mounjaro®. Mounjaro® typically starts at 2.5 mg. The dose generally increases every four weeks, up to a maximum dose of 15 mg weekly.

This gradual dose escalation helps manage common side effects like nausea, diarrhoea, and constipation.

Timing the Switch From Ozempic® to Mounjaro®

Usually, you’ll start Mounjaro® the week after your last Ozempic® injection. But follow the exact dosing schedule your GP or private provider gives you.

Dosage Ozempic® to Mounjaro® Conversion Chart

There isn’t an official Ozempic® to Mounjaro® conversion chart.

The medicines have different active ingredients (semaglutide vs. tirzepatide) and mechanisms (GLP-1 vs. GLP-1 and GIP). So they aren’t interchangeable milligram-for-milligram. Your provider will tailor your maintenance dosage based on your unique health profile and response to your medication.

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Side Effects of Mounjaro® vs. Ozempic®

Mounjaro® and Ozempic® have similar side effects, but they might differ in intensity.

Both weight loss medications share common side effects, including:

• Nausea

• Vomiting

• Diarrhoea

• Constipation

• Abdominal pain

• Indigestion

• Injection site reactions

They also both carry serious, but rare risks, including:

• Inflammation of the pancreas (acute pancreatitis)

• Gallbladder problems, including gallstones

• Kidney issues, sometimes linked to dehydration from vomiting

• Diabetic retinopathy complications (in those with type 2 diabetes)

• Increased heart rate

• Dangerously low blood sugar (hypoglycaemia), mainly if used with other diabetes medications

• Thyroid tumours (seen in rodent studies, not observed in humans)

Since Mounjaro® acts on both GLP-1 and GIP receptors, some people may experience more significant weight loss effects. But because of this dual action, the side effects of Mounjaro® might also be stronger, especially at higher doses.

Other Considerations of Switching From Ozempic® to Mounjaro®

Here’s what to bear in mind if you’re thinking of switching from Ozempic® to Mounjaro®:

• Drug shortages. Both medicines have faced availability issues in the U.K., which may influence access on the NHS or through a private prescription. Always check the gov.uk site for official updates.

• Eligibility. NHS prescribing criteria usually include a BMI of 35 or higher with a related health condition (like high blood pressure or heart disease). Sometimes, it might be prescribed to folks with a lower BMI — private providers may have broader criteria.

• Cost and access. Neither medication is available without a prescription. Costs are subject to change and vary depending on how you access the medicine.

If neither semaglutide nor tirzepatide suits you, ask your GP whether another option — like liraglutide (Saxenda®) or orlistat — might work for you.

In Summary: Switching From Ozempic® to Mounjaro®

Switching from Ozempic® to Mounjaro® is possible, but it’s not a straightforward swap. They’re different injectable medications with unique dosing schedules, active ingredients, and side effect profiles.

Your GP or private healthcare provider will help determine if switching makes sense for your weight loss goals or blood sugar control. They can guide you through your new treatment plan and adjust your maintenance dose as needed.

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FAQs

See answers to commonly asked questions about switching from Ozempic® to Mounjaro®.

Can you switch from Ozempic® to Mounjaro®?

Yes, you can switch from Ozempic® to Mounjaro®. But you should only do so under the supervision of a healthcare professional, like your GP or a private medical provider.

How long to wait when switching from Ozempic® to Mounjaro®?

Typically, you’ll start Mounjaro® the week after your last Ozempic® injection. Follow your provider’s exact instructions when making the switch.

Is there an Ozempic® to Mounjaro® conversion chart?

No, there isn’t a direct conversion chart for switching from Ozempic® to Mounjaro®. The two drugs have different active ingredients and mechanisms, so dosing must be individualised.

Is Mounjaro® better than Ozempic® for weight loss?

Some studies suggest Mounjaro® produces greater weight loss effects. But individual results vary, and both drugs have been shown to support substantial weight loss.

What are the side effects of switching to Mounjaro®?

Common side effects of switching to Mounjaro® (or increasing the dose) include nausea, diarrhoea, and constipation. Serious but rare risks include pancreatitis and gallbladder issues.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your GP about the risks and benefits of any treatment.