Ozempic vs Mounjaro

Ozempic and Mounjaro are two GLP-1 receptor agonists used for diabetes and weight loss. So how do they compare in terms of effectiveness, cost, accessibility, and other factors?
Simon Lovick
min read
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Quick summary

Deciding between Ozempic and Mounjaro for weight loss can be challenging. With the explosion in popularity of these two medication options, understanding the key differences is essential for making an informed choice. 

This guide tackles the pressing questions of efficacy, safety, costs, and more. Find out how Ozempic and Mounjaro compare on mechanism of action, blood sugar and weight reduction, side effects, NHS availability, and dosing. 

Ozempic vs Mounjaro: What's the difference?

Ozempic and Mounjaro are two GLP-1 receptor agonists used for diabetes and weight loss. While similar, there are some key differences between these two medications:

  • Approved Uses - Ozempic is approved for type 2 diabetes, while Mounjaro is approved for both type 2 diabetes and chronic weight management.
  • Active Ingredients - Ozempic contains semaglutide, while Mounjaro contains tirzepatide. Both activate GLP-1 receptors but Mounjaro also activates GIP receptors.
  • Dosing - Ozempic is injected at 0.25mg to 1mg once weekly. Mounjaro starts at 2.5mg weekly, increasing to 5mg, 7.5mg, and then 15mg weekly.
  • Efficacy - Mounjaro appears more effective at lowering A1C and body weight compared to Ozempic based on clinical trials so far.
  • Side Effects - They have similar side effect profiles, mainly GI effects. Mounjaro may have slightly higher initial nausea rates.
  • NHS Availability - Ozempic has limited NHS access for diabetes. Mounjaro currently does not have NHS coverage.
  • Cost - The cost varies depending on where you get your prescription from but both are likely to cost around £200-300 per month on a private prescription.
  • Long-term Data - Ozempic has over 5 years of clinical experience, while Mounjaro was only approved in 2022.

Mounjaro seems to offer enhanced efficacy but costs more and has less long-term safety data compared to the closely related Ozempic.

Ozempic vs Mounjaro: How they work

Ozempic (semaglutide) is an injectable medication that mimics the hormone GLP-1. This hormone helps regulate blood sugar levels by stimulating the release of insulin when blood sugar is high. 

Ozempic binds to receptors in the pancreas, slowing digestion and preventing the liver from releasing too much glucose. This lowers appetite and promotes weight loss. 

In summary, Ozempic stimulates insulin production, slows digestion, decreases appetite, and promotes weight loss through its effects on blood sugar and GLP-1 receptors.

How Mounjaro Works

Mounjaro (tirzepatide) is also an injectable medication that activates GLP-1 receptors. Like Ozempic, it helps control blood sugar by triggering insulin release and slowing digestion. But Mounjaro also binds to glucose-dependent insulinotropic polypeptide (GIP) receptors. 

The combined activation of GLP-1 and GIP receptors results in improved glucose control and increased weight loss compared to GLP-1 drugs like Ozempic. 

In short, Mounjaro mimics the actions of GLP-1 and GIP to lower blood sugar, suppress appetite, and drive weight loss.

Comparative Analysis

Both Ozempic and Mounjaro target GLP-1 receptors to control blood sugar and promote weight loss. However, Mounjaro also activates GIP receptors for enhanced effects. While they share a common mechanism of action via GLP-1, Mounjaro's dual approach leads to greater A1C and weight reductions. But Ozempic has a longer track record, having been on the market since 2017. 

Mounjaro is the newcomer, approved in 2022, with less real-world data. Time will tell whether Mounjaro maintains its superiority as more evidence emerges. But for now, Mounjaro appears to provide greater glucose and weight control owing to its dual agonism.

Efficacy in Blood Sugar Control

Ozempic's Effectiveness in Blood Sugar Control

Clinical trials demonstrate Ozempic's ability to lower blood sugar in type 2 diabetics. The SUSTAIN trials showed A1C reductions of 0.7-1.8% with Ozempic compared to placebo over 30-56 weeks. Patients receiving the highest 1 mg dose saw average A1C drops of 1.5%. 

Ozempic also lowered fasting blood glucose by 20-50 mg/dL across studies. Real world data confirms its effectiveness, with a meta-analysis of 38 studies showing Ozempic decreased A1C by 1.02% on average. In summary, substantial clinical evidence supports Ozempic's efficacy in improving glycemic control.

Mounjaro's Effectiveness in Blood Sugar Control

Mounjaro has been shown in clinical trials to effectively reduce A1C and blood glucose levels. The SURPASS trials demonstrated A1C reductions of 1.6-2.0% with Mounjaro versus placebo over 24-52 weeks. Even larger drops were seen in patients with higher baseline A1Cs. 

Across doses, Mounjaro lowered fasting blood glucose by 35-65 mg/dL. Real world data is still forthcoming, but clinical evidence clearly highlights Mounjaro's significant efficacy for blood sugar control.

Head-to-Head Comparison

Both Ozempic and Mounjaro effectively lower A1C and blood glucose, but Mounjaro appears superior. In head-to-head trials, Mounjaro reduced A1C by 0.36-0.67% more than Ozempic. The average A1C reduction with Mounjaro was 1.9% versus 1.4% with Ozempic. However, Ozempic has longer real world experience. 

Overall, the current clinical data gives Mounjaro an edge in efficacy, but longer-term evidence is needed. Either way, both offer substantial improvements in blood sugar management.

Weight Loss Efficacy

Ozempic and Weight Loss

Clinical trials demonstrate Ozempic's ability to drive weight loss in overweight and obese patients. The SUSTAIN trials showed average weight reductions of 4-6 kg (8-13 lbs) with Ozempic 1 mg over 30-56 weeks versus placebo. 

A meta-analysis of 15 studies found Ozempic lowered body weight by 6.5 kg on average. Real world evidence also confirms its effectiveness for weight loss in routine clinical practice. Overall, substantial data supports Ozempic as an effective weight loss agent.

Mounjaro and Weight Loss

Mounjaro has been shown in clinical studies to be highly effective for weight loss. In the SURMOUNT trials, Mounjaro doses of 5-15 mg led to average weight reductions of 11-14.5 kg (24-32 lbs) compared to placebo over 68 weeks. 

Over 25% of patients lost ≥20% body weight with Mounjaro 15 mg. Additional trials like SURPASS-2 and -3 confirmed significant weight loss, with average decreases of 13.2-13.7 kg. Thus, robust clinical evidence demonstrates Mounjaro's potent weight loss effects.

Comparative Analysis in Weight Loss

Both Mounjaro and Ozempic promote weight loss, but Mounjaro appears more efficacious. In head-to-head studies, Mounjaro 15 mg led to ~2.4 kg greater weight loss than Ozempic 1 mg over 68 weeks. Nearly three times as many patients lost ≥15% weight with Mounjaro. 

However, long-term real world data is still lacking for Mounjaro compared to Ozempic's 5+ years of use. However, based on clinical trials so far, Mounjaro seems to offer superiority in terms of weight loss efficacy.

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Ozempic Vs Mounjaro: Side effects

Common Ozempic side effects include nausea, vomiting, diarrhea, abdominal pain, decreased appetite, and constipation. These usually occur during the first 2 weeks and decline over time. Less common effects are dizziness, headache, fatigue, indigestion, and gastritis. 

Most side effects are mild to moderate. However, Ozempic may increase the risk of thyroid cancer, pancreatitis, gallbladder issues, and severe hypoglycemia. Acute kidney injury has also been reported. Overall, Ozempic has a manageable safety profile when used appropriately.

Mounjaro's common side effects mirror Ozempic's and include nausea, diarrhea, decreased appetite, vomiting, constipation, and abdominal pain. These also tend to diminish with continued treatment. 

Less frequent adverse effects are dyspepsia, gastroesophageal reflux, fatigue, dizziness, and rash. As with Ozempic, severe hypoglycemia and acute kidney injury are potential risks. Gallbladder-related effects and pancreatitis are also concerns. 

Mounjaro may carry slightly higher GI side effect risks based on clinical trials.

Administration and Doses

How to Administer Ozempic

Ozempic is administered via subcutaneous injection into the thigh, abdomen, or upper arm. The recommended starting dosage is 0.25 mg once weekly, increased to 0.5 mg after 4 weeks if needed. The maintenance dose is typically 0.5 or 1 mg injected once weekly. 

Patients should rotate injection sites and use proper injection techniques to minimize side effects. Ozempic comes in a pre-filled pen for ease of use.

How to Administer Mounjaro

Mounjaro is also given as a subcutaneous injection, with the thigh, abdomen, or upper arm as suitable sites. The starting dose is 2.5 mg once weekly for 4 weeks. This is then increased to 5 mg for 4 weeks and then the maintenance dose of either 7.5 mg or 15 mg. 

As with Ozempic, rotating sites and proper injection technique helps reduce irritation. Mounjaro is available in an automatic single-dose pen.

Dosage Comparison

Both drugs are injected subcutaneously once weekly. But Mounjaro starts at a lower dose that is increased more slowly over 12 weeks. The maximum Ozempic dose is 1 mg versus 15 mg for Mounjaro. 

Mounjaro's dose titration aims to minimize GI side effects. The pens simplify administration for both. Following the recommended dosage schedule helps optimize efficacy and tolerability

NHS Availability and Alternative Purchasing Options

Ozempic on the NHS

Ozempic is available on the NHS in some regions for treating type 2 diabetes, subject to local clinical commissioning group guidance. Eligibility criteria typically include:

  • HbA1c of 58 mmol/mol (7.5%) or higher despite other medications
  • BMI over 35 kg/m2

If prescribed on the NHS, patients pay the standard prescription charge per Ozempic pen. Currently, this is £9.35 per item in England. Some patients may qualify for free prescriptions.

Mounjaro on the NHS

Mounjaro does not yet have NHS approval or funding for diabetes or weight loss. Individual CCGs may approve its use but this is unlikely at present. 

Patients can follow NICE guidance and request an individual funding request if Mounjaro is deemed clinically appropriate by their physician. But access will be very restricted initially.

Alternative Purchasing Options

Without NHS availability, the only options are private prescriptions or online pharmacies. A private prescription for Ozempic or Mounjaro might cost around £300 for a 28-day supply. 

At Habitual we offer plans that include a Wegovy prescription. Wegovy is another brand name for semaglutide but one that is approved for weight management in the UK. You can read about the differences between Wegovy and Mounjaro here.


Mounjaro appears to offer enhanced blood sugar and weight control owing to its dual agonism of GLP-1 and GIP receptors. However, Ozempic has a longer track record of proven real-world efficacy and safety.

Both provide substantial improvements in managing diabetes and driving weight loss. But Mounjaro's higher costs and lack of NHS availability make Ozempic the more accessible option for most patients currently.

Proper dosing, administration, and side effect management will optimize outcomes regardless of which medication is selected. Following clinical guidance and individualizing therapy based on each person's needs is advised.


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