Mounjaro vs Ozempic: Lose weight with a UK-licensed medication

Both Mounjaro and Ozempic are injectable medications that help control blood sugar levels in adults with type 2 diabetes.

They’ve also gained significant attention for their medical weight loss effects.

Ozempic is more well known than Mounjaro. It was launched several years earlier and its time in the media spotlight has made it a familiar brand name in weight management.

However, only Mounjaro is approved specifically as a weight loss treatment. It’s not possible to get Ozempic for weight loss in the UK.

Mounjaro has similar effects and side effects to Ozempic. And it’s been shown to outperform Ozempic in clinical trials. But since the public doesn’t hear about Mounjaro as much, the idea of taking it may make some people uneasy.

In this guide, we explore the similarities and differences of Mounjaro and Ozempic, including how they work and what you can expect from your weight loss program.

By presenting a clear, medically accurate weight loss injection comparison, we help you make informed decisions about your healthcare.

How do Mounjaro and Ozempic work?

Mounjaro’s dual GIP and GLP-1 mechanism

The active ingredient in Mounjaro is tirzepatide.

This medication supports weight loss by mimicking two hormones secreted by the intestine:

• Glucose-dependent insulinotropic polypeptide (GIP)
• Glucagon-like peptide-1 (GLP-1)

GIP plays a pivotal role in regulating blood sugar and fat metabolism. It:

• Enhances insulin sensitivity: GIP can improve insulin action in fat tissue, helping to reduce blood glucose (sugar) levels and indirectly support fat metabolism
• Helps regulate appetite: By binding onto hormone receptors in the brain, GIP reduces your appetite and helps you eat less
• Promotes fat burning: Evidence suggests that GIP alters fat metabolism, encouraging your body to break fat down rather than store it
• Reduces inflammation: GIP may reduce inflammation in fat tissue, improving your overall metabolic health

GLP-1 is similar, but has a greater effect on appetite regulation and insulin secretion. GLP-1 agonist medications can:

• Trigger insulin release: Insulin allows your cells to absorb glucose from your bloodstream and use it as energy
• Suppress glucagon: Limiting glucagon prevents the liver from releasing stored glucose and helps keep blood sugar stable
• Slow stomach emptying: By increasing the time it takes for food to move through your digestive system, GLP-1 helps you feel fuller for longer
• Reduce appetite: When GLP-1 agonists bind with brain receptors, they signal to your body that you’re not hungry

The inclusion of GIP enhances the effects of GLP-1.

This amplifies the weight loss effects of Mounjaro, helping you lose more weight and reducing your risk of heart, kidney and fatty liver disease.

You can buy Mounjaro online by registering as a patient with The Online Clinic and submitting a medical health questionnaire for review by a UK-licensed doctor.

Ozempic is only a GLP-1 agonist

The active ingredient in Ozempic – semaglutide – only mimics the GLP-1 hormone.

Using Ozempic can contribute to weight loss by controlling blood sugar and reducing appetite.

But while the results are significant, its potential is limited without the enhancing effects of GIP.

As such, a prescription for Mounjaro can actually produce much better results than Ozempic for weight loss.

If you’re still concerned about taking Mounjaro, our UK-licensed doctors are available to oversee your treatment.

You can schedule follow-up consultations to monitor the effects of your medication and make adjustments to improve your results.

Register online today to request a Mounjaro prescription.

Effectiveness and results of Mounjaro vs Ozempic

Novo Nordisk, the manufacturers of Ozempic, report an average weight loss of 14 lbs in patients given 2mg of Ozempic for 40 weeks.

These results are certainly compelling.

But since Ozempic isn’t prescribed for weight loss in the UK, the results are of limited use. Please note however that semaglutide is available as the Wegovy brand for weight loss in the UK.

Tests of Mounjaro vs Ozempic by Mounjaro manufacturers Ali Lilly and Company were even more impressive.

These showed an average weight loss of 25 lbs in patients given 15mg of their drug for 40 weeks.

However, this data is provided by the manufacturers as part of their marketing material.

So it’s easy to be sceptical that they might be cherry picking the best results.

To confirm the effectiveness and results of Mounjaro vs Ozempic and their active ingredients tirzepatide vs semaglutide, let’s take a closer look at some other clinical trials.

Tirzepatide SURMOUNT trials

The SURMOUNT trials, described in the article Tirzepatide once weekly for the treatment of obesity in The New England Journal of Medicine, examined tirzepatide weight loss effects on 2,539 participants over 72 weeks.

94.5% of these participants had a body mass index (BMI) of 30 or higher, and none were diagnosed with diabetes.

Those not in a placebo group received a weekly dose of tirzepatide at either 5mg, 10mg or 15mg, with the following results:

Semaglutide STEP trials

The Semaglutide Treatment Effect in People with Obesity (STEP) trials, as summarised in the article Once-weekly semaglutide in adults with overweight or obesity in The New England Journal of Medicine, studied semaglutide weight loss effects in 1,961 adults.

Participants included those with a BMI of 30 or greater, or of 27 or greater in those with at least one weight-related co-existing condition. No participants were diagnosed with diabetes.

At a semaglutide dosage of 2.4mg alongside a reduced-calorie diet and increased physical activity, average weight loss was 15.3 kg (14.9% of total body weight) over 68 weeks.

This is compared to an average loss of 2.6 kg (2.4%) in the placebo group.

What does this mean for you?

In the weight loss comparison of Mounjaro vs Ozempic – or tirzepatide vs semaglutide – clinical trial data shows that Mounjaro is much more effective for weight loss.

Side effects comparison

The side effects of Mounjaro and the side effects of Ozempic are essentially the same.

Common side effects of both medications include:

• Nausea
• Diarrhoea
• Vomiting
• Constipation
• Indigestion
• Stomach pain
• Injection site reactions

These are usually mild and tend to occur when the dose is increased. But they decrease over time as your body adjusts to the medication.

While rare, more serious side effects can include:

• Severe allergic reactions (anaphylaxis)
• Increased heart rate
• Risk of high or low blood sugar
• Severe stomach problems
• Gallbladder issues
• Pancreatitis
• Kidney damage
• Thyroid tumours
• Diabetic retinopathy, mainly in those with existing eye disease

If you experience any serious side effects, seek immediate medical attention.

Which medication is better tolerated?

There’s some evidence that the GIP agonism of Mounjaro could reduce nausea and vomiting associated with GLP-1 agonist medications.

This could allow for higher doses that further accelerate weight loss.

However, the gastrointestinal side effects of Mounjaro tend to be more common and more severe than those of Ozempic.

This is why your doctor will only recommend Mounjaro for weight loss if the benefits significantly outweigh the risks.

Register as a patient with The Online Clinic and book a consultation with a UK-licensed doctor to find out if taking Mounjaro is right for you.

Dosage and administration

Please note that Ozempic is NOT prescribed for weight loss in the UK. There is another medication that contains Semaglutide called Wegovy. Ozempic is only prescribed for type 2 diabetes.

NHS availability in the UK

Ozempic is available for prescription through the NHS.

However, it’s only approved for the treatment of type 2 diabetes.

That’s because overuse of Ozempic for weight loss led to shortages that kept people with type 2 diabetes from getting the medication they needed.

In response, the UK regulator approved alternative drugs for use in weight management.

One of these is Mounjaro. The other is Wegovy.

You can get an NHS prescription for Mounjaro or Wegovy by meeting certain criteria. Wegovy is described on another page on our website.

Mounjaro prescription requirements

As of 23 March 2025, you can get a prescription for Mounjaro through the NHS if it is prescribed by a specialist weight management service.

The National Institute for Health and Care Excellence (NICE) recommends Mounjaro for weight loss only when someone has a BMI of at least 35 as well as at least one other weight-related condition.

A lower BMI limit applies for people from Black African, African-Caribbean, Asian, South Asian, Chinese, and Middle Eastern backgrounds who have additional medical conditions related to obesity.

Why get a private Mounjaro prescription online?

Although Mounjaro is available through the NHS, many people still prefer to get it from an online healthcare provider.

The benefits of a private online Mounjaro prescription include:

• Shorter wait times: You could wait weeks for an NHS appointment, and even longer for your prescription to be approved. Online clinics and pharmacies don’t have the same overwhelming patient load, meaning we can process your request much more quickly
• Broader eligibility: The NHS has very strict criteria for prescribing Mounjaro. But online pharmacies can prescribe weight loss medication for patients of lower BMI thresholds and without comorbidities after a thorough medical assessment
• Accessibility and convenience: With an online provider, you can get a Mounjaro prescription from the comfort of your own home. This makes it especially useful for those with mobility issues or who live far from their nearest NHS surgery or dispensary
• Rapid delivery: Many online doctors offer next-day delivery. So you can receive your medications, start your treatment and take your first steps to a healthier lifestyle right away
• Total privacy: We deliver all medications in discreet packaging with no mention of the contents or The Online Clinic. That means you can take control of your healthcare without worrying about other people

Mounjaro vs Ozempic: Weight loss injection comparison

Get an online Mounjaro prescription from a trusted UK doctor

With over 20 years as an online healthcare provider, The Online Clinic is one of the most trusted and well-established online clinics and pharmacies in the UK.

Our team includes all UK-licensed doctors who review prescription requests thoroughly to ensure all medications are dispensed ethically and with good reason.

The Online Clinic is regulated by the Care Quality Commission (CQC), whose latest report confirmed our high level of quality and service.

Mounjaro Very clinical and professional service. I felt very happy and secure knowing everything was medically verified before starting Mounjaro. Immediately I felt less bloated and had more energy. I have lost 4 lbs within 3 days, which for someone with Hypothyroidism is a wonderful feeling. I'm looking forward to the next weeks and months. It's easily administered, and everything is explained thoroughly. I would highly recommend The Online Clinic and their service. Lisa Ryan

Register as a patient today

Register online today and complete a short medical health questionnaire to request an online prescription for Mounjaro from a licensed UK doctor.

Mounjaro vs Ozempic frequently asked questions

What’s the difference between Mounjaro and Ozempic?

Mounjaro is a dual GIP and GLP-1 agonist medication that uses tirzepatide as the active ingredient.

It’s administered as a weekly injection with a multi-use auto-injector pen starting at 2.5mg, with a maximum dose of 15mg.

Ozempic is a GLP-1 receptor agonist with the active ingredient semaglutide.

The weekly injection is administered using a multi-dose pen at doses starting at 0.25mg and reaching up to 2mg. The Wegovy brand of Semaglutide is licensed up to 2.4 mg.

Which is more effective for weight loss, Mounjaro or Ozempic?

In clinical trials, weekly tirzepatide doses of 15mg led to an average weight reduction of 23.6 kg (22.5%) over 72 weeks.

In contrast, weekly semaglutide doses of 2.4mg lead to an average weight reduction of just 15.3 kg (14.9%) over 68 weeks.

This suggests that Mounjaro is more effective than Ozempic or Wegovy for weight loss.

Are the side effects of Mounjaro worse than Ozempic?

The side effects of Mounjaro and Ozempic are similar.

However, while Mounjaro is less likely to cause nausea and vomiting, it’s more likely to cause severe gastrointestinal side effects.

Can I switch from Ozempic to Mounjaro?

Yes, under medical supervision.

Regardless of how long you’ve been taking Ozempic, you’ll need to start taking Mounjaro at the initial 2.5mg dose and increase gradually over time.

Remember that Ozempic isn’t licensed for weight loss in the UK. So this is only relevant to those taking Ozempic for type 2 diabetes.

Useful resources for understanding Mounjaro vs Ozempic

Novo Nordisk

• What is Ozempic?
• How Ozempic works
• Possible side effects of Ozempic

Eli Lilly and Company

• How Mounjaro works
• Clinical weight data

WedMD

• Mounjaro (tirzepatide) – Uses, side effects, and more
• Ozempic (semaglutide) – Uses, side effects, and more

National Health Service (NHS)

• Weight loss guidelines
• Obesity treatment
• Eating a balanced diet
• Exercise