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Mounjaro vs Wegovy: A Comprehensive Comparison

Health statistics published in 2021 showed that just over a quarter (25.9%) of adults in England are obese and almost 38% are clinically overweight. The proportion of overweight or obese adults in the UK has risen by 11.4% since 1993, becoming a burden not only for those living with the condition but for the NHS too.

Recently, the introduction of weight loss injections means that for those who meet the eligibility criteria, losing weight may be easier, especially for anyone who has endured long-standing weight loss difficulties.

Two examples that have been approved for weight loss in the UK are Mounjaro and Wegovy. Although they work similarly and belong to the same class of medicines, GLP-1 receptor agonists, they differ in their active ingredients, average weight loss results, and dosage.

Mounjaro vs Wegovy: At a glance

  • Mounjaro and Wegovy are GLP-1 receptor agonists but they contain different active ingredients
  • Mounjaro also mimics another hormone involved in appetite regulation and blood sugar control, glucose-dependent insulinotropic polypeptide (GIP)
  • Research suggests Mounjaro induces a greater body weight reduction compared to Wegovy

Mounjaro vs Wegovy: Active ingredients and how they work

The active ingredients in Wegovy and Mounjaro are key to their weight loss capabilities, but they differ in their overall composition.

Mounjaro contains the active ingredient tirzepatide and Wegovy contains semaglutide. Both medicines are glucagon-like peptide-1 (GLP-1) receptor agonists, which means they mimic the effects of GLP-1 hormones. They work by:

  • Activating GLP-1 receptors to decrease appetite and calorie intake
  • Delaying the emptying of the stomach
  • Lowering blood sugar levels by increasing glucose uptake in the muscles and stopping the production of glucagon by the pancreas when sugar levels are high

Mounjaro is a dual agonist because it is not only a GLP-1 receptor agonist but also mimics the actions of another hormone, glucose-dependent insulinotropic polypeptide (GIP). That means by mimicking both GLP-1 and GIP hormones, Mounjaro improves the body’s response to insulin and blood glucose levels. By acting on the parts of the brain responsible for appetite regulation and delaying the time it takes for food to make it through the digestive tract, Mounjaro also decreases food intake, contributing to significant weight loss.

What are the dosage and administration differences between Mounjaro and Wegovy?

Because Mounjaro and Wegovy contain different active ingredients, their dosage and administration schedules differ.

MonthMounjaro (mg/week)Wegovy (mg/week)

The starting dose for Mounjaro is 2.5 mg and can be increased to a maximum maintenance dose of 15 mg/week. The starting dose for Wegovy is 0.25 mg increasing to a maximum maintenance dose of 2.4 mg/week.

For both weight loss injections, the doses increase incrementally every 4 weeks but it is possible to remain on the current dose if you experience side effects.

Weight loss efficacy

Several clinical trials have been conducted to assess the effectiveness of both Mounjaro and Wegovy.

The SURMOUNT-1 trial looked at the efficacy of Mounjaro in non-diabetic obese or overweight individuals over 72 weeks. The results of the study demonstrated that the mean percentage weight change over 72 weeks was as follows:

Tirzepatide dose (mg)Weight change (%)

Of those who used the maintenance dose of 15 mg/week, 91% achieved at least a 5% weight reduction and 57% achieved a 20% body weight reduction.

A later follow-up study, SURMOUNT-4, investigated the effect of tirzepatide alongside a diet and exercise programme on sustained weight loss.

The results showed that after 36 weeks at a maximum tolerated tirzepatide dose of 10 or 15 mg, overweight or obese adults who were not diabetic achieved an average weight loss of 20.9%. After week 36, those who switched to a placebo, gained 14% weight while those who continued with tirzepatide treatment lost an additional 5.5% during a 52-week double-blind period. Overall, the study demonstrated that stopping tirzepatide causes weight gain, whereas continued treatment helped to maintain the reduction.

To determine the efficacy of semaglutide, the active ingredient in Wegovy, the STEP -1 trial was conducted, involving 1961 non-diabetic obese or overweight adults across 68 weeks.

The main results were that the average body weight change in the semaglutide group from baseline to 68 weeks was -14.9% compared to -2.4% in the placebo group. In the semaglutide group, participants lost 15.3 kg compared to 2.6 kg in the placebo group across the 68-week trial.

A further trial, the STEP-4 trial, found that continuing with the semaglutide maintenance dose of 2.4 mg/week was more effective for continued weight loss than switching to a placebo. The researchers found that those who switched to a placebo following a 20-week semaglutide run-in period regained weight compared to those who continued with semaglutide. The estimated weight reduction in this group was 17.4% across the 68-week trial.

Overall, the efficacy of Wegovy and Mounjaro is dependent on your overall lifestyle. To gain the maximum benefit from weight loss injections, it is important to take a holistic approach to losing weight which means incorporating lifestyle changes, such as participating in regular exercise and following a healthy diet.

Mounjaro vs Wegovy costs

The cost of Wegovy and Mounjaro weight loss injections is equivalent to 4 weeks of treatment. There are slight price differences.

Below are price comparison tables for purchasing Mounjaro or Wegovy from Prescription Doctor.

Wegovy Pack sizeDosagePrice
x 1 Pen Starter Pack0.25mg£168.99
x 1 Pen Continuation Pack0.5mg£168.99
x 1 Pen Continuation Pack1mg£168.99
x 1 Pen Continuation Pack1.7mg£223.99
x 1 Pen Maintenance Pack2.4mg£268.99
3 Month Supply1 x 0.25mg
1 x 0.5mg
1 x 1.0mg
Mounjaro Pack SizeDosagePrice
Starter2.5 mg£159.99
Maintenance5.0 mg£159.99
Starter and maintenance combo2.5 mg & 5 mg£307.99

Where to get Mounjaro or Wegovy for weight loss

Mounjaro and Wegovy are available for purchase from Prescription Doctor.

You will need to complete a short online consultation which consists of an online medical questionnaire, to help our clinicians determine if a weight loss injection is appropriate for you.

You must meet the eligibility criteria to qualify for Wegovy or Mounjaro weight loss treatment.

If our clinicians decide your chosen treatment is not suitable, you will receive a full refund as part of our money-back guarantee.


Although Mounjaro appears to induce a greater body weight loss, it is important to consider the differences between Wegovy and Mounjaro, such as effectiveness, dosage schedule, potential side effects, and cost.

Both offer promising weight loss results when used alongside lifestyle changes, including a diet and exercise plan. Our clinicians will help determine if Wegovy or Mounjaro are right for you and your weight loss journey.

At Prescription Doctor, we also offer a range of alternative weight loss treatments, including pills such as MySimba and Xenical.


Authored & Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist
Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Published on: 23/04/2024 Reviewed on: 23/04/2024
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