Mounjaro vs Wegovy: which is better for weight loss?

Mounjaro produced greater average weight loss in the main head-to-head trial, but the study compared it with Wegovy doses up to 2.4 mg. It did not compare Mounjaro with the newer Wegovy 7.2 mg dose. [1]

Both medicines can support weight management. Which suits you depends on your medical history, response, side effects and the cost of continuing treatment.

This guide compares the weekly injections for UK adults, explains the current evidence and covers the questions to discuss with your prescriber.

Medino is a UK online pharmacy. The prices below come from Medino's own listings. This article provides general information and does not replace a prescribing assessment.

Mounjaro vs Wegovy at a glance

Feature	Mounjaro	Wegovy injection
Active ingredient	Tirzepatide	Semaglutide
Receptors targeted	GIP and GLP-1	GLP-1
Frequency	Once weekly	Once weekly
Starting dose	2.5 mg weekly	0.25 mg weekly
Adult maintenance doses	5 mg, 10 mg or 15 mg weekly	2.4 mg weekly; 7.2 mg may be prescribed for adults with obesity if needed
How you obtain treatment	Prescription after assessment	Prescription after assessment

Sources: UK prescribing information and NHS medicine guidance. [2–5]

What is the difference between Mounjaro and Wegovy?

Mounjaro contains tirzepatide; Wegovy contains semaglutide. Wegovy activates the GLP-1 receptor, while Mounjaro activates both GLP-1 and GIP receptors. These pathways help regulate appetite and blood sugar. Both can reduce hunger and help you feel fuller, supporting a reduced-calorie eating plan. [4, 5]

Their milligram doses are not interchangeable. A higher number on one pen does not mean it is equivalent to, or stronger than, a dose of the other medicine. [2, 3]

The difference in how they work also does not predict which you will tolerate better.

Which causes more weight loss?

SURMOUNT-5 found greater average weight loss with tirzepatide than semaglutide at 72 weeks. The randomised, open-label trial enrolled 751 adults with obesity or overweight with a qualifying complication, without diabetes. It compared maximum tolerated doses of tirzepatide, 10 mg or 15 mg, with semaglutide, 1.7 mg or 2.4 mg. [1]

SURMOUNT-5 outcome at 72 weeks	Tirzepatide	Semaglutide
Estimated average body-weight reduction	20.2%	13.7%
Estimated average weight lost	22.8 kg	15.0 kg
Estimated proportion losing at least 15%	64.6%	40.1%
Estimated proportion losing at least 20%	48.4%	27.3%
Estimated proportion losing at least 25%	31.6%	16.1%

The average difference was 6.5 percentage points. These estimates include statistical handling of missing data; they are not predictions of your personal results. The trial was funded by Eli Lilly, Mounjaro's manufacturer. [1]

Its results do not establish the expected weight loss in people with type 2 diabetes or a direct comparison with higher-dose Wegovy.

Does Wegovy 7.2 mg change the comparison?

Yes. Wegovy 2.4 mg is no longer the highest licensed weekly dose for eligible UK adults with obesity. If needed, a prescriber may increase treatment to 7.2 mg after at least four weeks on 2.4 mg. It is not a starting dose or an automatic next step. [3, 6]

The separate STEP UP trial compared Wegovy 7.2 mg, Wegovy 2.4 mg and placebo in adults with obesity without diabetes.

STEP UP results at 72 weeks	Wegovy 7.2 mg	Wegovy 2.4 mg
Estimated weight reduction accounting for treatment discontinuation and other weight-loss interventions	18.7%	15.6%
Estimated weight reduction assuming continued treatment without other weight-loss interventions	20.7%	17.5%

These are two analyses of the same trial, answering different questions about treatment use. STEP UP did not include Mounjaro. Its percentages cannot be placed alongside SURMOUNT-5 to declare which medicine would win in a direct comparison. [3]

The practical point is that the older head-to-head result remains useful, but it does not cover every current Wegovy option.

Which has fewer side effects?

Neither medicine is reliably gentler for everyone. Both can cause nausea, vomiting, diarrhoea, constipation and digestive discomfort. Symptoms may be more noticeable when treatment starts or the dose increases. [7, 8]

The direct trial provides some context:

Event reported in SURMOUNT-5	Tirzepatide	Semaglutide
Nausea	43.6%	44.4%
Vomiting	15.0%	21.3%
Stopped trial treatment because of adverse events	6.1%	8.0%

These results concern the doses studied. They do not establish that one medicine is safer overall or predict your experience. [1]

Tell your prescriber if symptoms interfere with eating, drinking or daily life, particularly before a dose increase. Both medicines have important risks, including pancreatitis, gallbladder problems and dehydration. Insulin or sulphonylureas can increase the risk of low blood sugar when used with these treatments. [7, 8]

Stop treatment and seek urgent medical help for severe, persistent stomach pain, especially pain spreading to your back, with or without vomiting. This may be pancreatitis. [9]

Semaglutide also carries a warning about a very rare eye condition called NAION. Sudden loss of vision needs urgent assessment at eye casualty or A&E. Call 999 for breathing difficulty or swelling of the tongue or throat that may indicate a severe allergic reaction. [8, 10]

Hair loss and preserving muscle

Hair loss is reported in the product information for both medicines. Do not assume every case is caused by rapid weight loss or that it will always be temporary; discuss persistent or concerning shedding with your clinician. [7, 8]

Weight loss can also involve loss of muscle. Ask your treatment team about adequate nutrition, protein and suitable muscle-strengthening activity. These support health during weight loss and are separate from managing hair shedding. [11]

How do the doses compare?

Both treatments start low and increase gradually. The licensed schedules below are a guide; your prescriber should decide how you progress.

Mounjaro dosing

Mounjaro starts at 2.5 mg weekly for four weeks, then increases to 5 mg. Further increases, if needed, are in 2.5 mg steps after at least four weeks on the current dose. Adult maintenance doses are 5 mg, 10 mg or 15 mg weekly. Reaching 15 mg is not necessary for everyone. [2]

Wegovy injection dosing

Wegovy normally progresses through 0.25 mg, 0.5 mg, 1 mg and 1.7 mg, spending four weeks at each stage before reaching 2.4 mg weekly. Eligible adults with obesity may progress to 7.2 mg after at least four weeks on 2.4 mg. Significant digestive symptoms may require delaying an increase. [3]

Do not change your dose to match someone else's progress.

Who can take Mounjaro or Wegovy?

For adult weight management, both are licensed alongside a reduced-calorie diet and increased physical activity for an initial BMI of:

30 or above, or
27 to below 30 with at least one weight-related health condition. [2, 3]

Meeting a threshold does not guarantee a prescription. Your medical history and other medicines also need assessment.

Mounjaro is additionally licensed for insufficiently controlled type 2 diabetes. Semaglutide products used specifically for diabetes include Ozempic and Rybelsus; these should not be confused with choosing a Wegovy prescription for weight management. [2, 5]

Wegovy has an additional indication to reduce major cardiovascular events in adults with established cardiovascular disease and BMI ≥27. Raise any history of heart attack, stroke or other cardiovascular disease during your assessment. This indication does not establish that Wegovy is the better choice for every person with a heart condition. [3]

Can you get either medicine on the NHS?

Yes, but access is more restricted than the general licensing criteria. In England, Wegovy for weight management is prescribed through specialist services. Mounjaro access is being introduced in phases, including primary care, prioritising people with the greatest clinical need. Arrangements differ across the UK. [12]

Ask your GP about your local pathway. Private prescribing eligibility does not automatically mean NHS eligibility.

How much do Mounjaro and Wegovy cost per four weeks?

Compare ongoing costs at your prescribed dose, as well as the first prescription. Medino's listed prices below were checked on 13 October 2026.

Mounjaro KwikPen — weekly dose and price	Wegovy — weekly dose and price
2.5 mg — £147.99	0.25 mg — £99.99
5 mg — £169.99	0.5 mg — £99.99
7.5 mg — £249.99	1 mg — £105.99
10 mg — £269.99	1.7 mg — £169.99
12.5 mg — £299.99	2.4 mg — £229.99
15 mg — £319.99	7.2 mg — £249.99

Prices cover four weekly doses and were checked on 13 October 2026. Wegovy doses up to 2.4 mg use FlexTouch pens. Prices may change.

Rows show product prices, not equivalent doses or a switching schedule.

You can check current product listings and pack details on our Mounjaro and Wegovy brand pages. Treatment is subject to a prescribing assessment.

Sources: Medino product listings and pen information. Prices may change. The doses are not clinically equivalent. [2, 3, 13, 14]

A four-week supply covers 28 days, rather than a calendar month. Continuous treatment therefore requires approximately 13 four-week supplies per year.

Prices also vary between providers. For a broader comparison by dose, see our Mounjaro price comparison and Wegovy price comparison. Check whether each price includes a discount and whether its conditions apply to you.

Check delivery, needles, consultation charges and the support included before calculating your total. These listed product prices do not establish that every additional cost is included.

Can you switch from Wegovy to Mounjaro, or vice versa?

A switch may be possible after a prescribing assessment. Reasons to discuss a change include side effects, insufficient benefit, affordability or availability.

There is no simple milligram-for-milligram conversion. Do not take the medicines together. Your prescriber needs to decide when to stop one, when to start the other, the starting dose and monitoring. Wegovy should not be combined with other GLP-1 receptor agonist products. [3]

Bring your current dose, last injection date, treatment gaps and side-effect history to the review. A switch does not guarantee better results.

What happens if you stop treatment?

Weight regain can occur after stopping either medicine. Two withdrawal studies illustrate why a maintenance plan matters:

In the STEP 1 extension, participants regained approximately two-thirds of their previous weight loss over the year after semaglutide and structured lifestyle support were withdrawn. [15]
In SURMOUNT-4, participants switched from tirzepatide to placebo gained an average of 14.0% from their week-36 weight over the following 52 weeks. Those continuing tirzepatide lost a further 5.5%. [16]

These studies used different designs and reference points. They do not show which medicine causes more regain after stopping.

Discuss long-term treatment, nutrition, physical activity and what to do during a treatment gap before you start.

Does pregnancy or contraception affect the choice?

Neither medicine should be used during pregnancy. If you are planning pregnancy, discuss stopping Mounjaro at least one month beforehand or Wegovy at least two months beforehand. [4, 5]

If you use the contraceptive pill with Mounjaro, add barrier contraception or switch to a non-oral method for four weeks after starting and four weeks after each dose increase. [17]

Vomiting or severe diarrhoea can also affect pill protection. Ask your pharmacist or contraception service what to do if this happens. If you are breastfeeding, speak to your doctor before starting or continuing treatment. [7, 8]

Is there a Wegovy tablet or a Mounjaro pill?

Wegovy tablets were authorised in the UK in June 2026. They contain semaglutide and are taken daily with specific fasting and timing instructions. They are a different treatment format from the weekly injections compared here. [18]

Mounjaro contains tirzepatide and is supplied as an injection. A different tablet made by the same manufacturer is not automatically a tablet version of Mounjaro. [2]

The injection results above should not be used as a direct comparison with oral Wegovy.

How do I decide which treatment is right for me?

Ask your prescriber:

What benefits are we aiming for, and when will we review progress?
Does my medical history favour one option?
How will we manage side effects or a treatment gap?
What is the likely ongoing cost?
What is the plan for maintaining weight loss?

Sources

Last updated: 13 October 2026