Wegovy Versus Mounjaro: What Is the Difference?
Wegovy Versus Mounjaro: What Is the Difference?
Wegovy and Mounjaro are two of the most widely discussed prescription medicines used for weight management in the UK.
Both can influence appetite, help people feel fuller and support weight reduction when used as part of an appropriate weight management programme.
However, Wegovy and Mounjaro are not the same medicine.
Wegovy contains semaglutide.
Mounjaro contains tirzepatide.
They act on different hormone pathways, use different doses and have different prescribing considerations.
There is also no single treatment that is automatically right for everyone.
The appropriate treatment depends on the individual patient's health, medical history, current medicines, potential risks and clinical assessment.
What Is Wegovy?
Wegovy contains the active ingredient semaglutide.
Semaglutide acts on a hormone receptor known as GLP 1.
GLP 1 stands for glucagon like peptide 1.
It is a hormone naturally released by the digestive system after eating and is involved in regulating:
Appetite Feelings of fullness Digestion Insulin release Blood sugar
Semaglutide mimics some of the effects of natural GLP 1.
For weight management, this can help people feel full sooner and remain satisfied for longer.
Wegovy is authorised in the UK for weight management in appropriate adults alongside a reduced calorie diet and increased physical activity.
What Is Mounjaro?
Mounjaro contains the active ingredient tirzepatide.
Tirzepatide differs from semaglutide because it acts on two hormone receptors.
These are:
GLP 1
and
GIP
GIP stands for glucose dependent insulinotropic polypeptide.
Both hormone pathways are involved in areas such as appetite and blood sugar regulation.
Mounjaro is authorised in the UK for weight management in appropriate adults as well as for certain uses in type 2 diabetes.
What Is the Main Difference Between Wegovy and Mounjaro?
The simplest difference is how the medicines work.
Wegovy
Contains semaglutide
Acts on the GLP 1 receptor
Mounjaro
Contains tirzepatide
Acts on both the GLP 1 and GIP receptors
Both can reduce appetite and increase feelings of fullness.
However, tirzepatide's action on a second hormone pathway means it works differently from semaglutide.
You can read more about these hormone pathways in our guide:
GLP 1 Medicines Explained: What Are They?
How Do Wegovy and Mounjaro Affect Appetite?
Both treatments can make it easier for some people to eat less by changing how hunger and fullness are experienced.
People may notice:
Feeling full sooner Smaller portions becoming more satisfying Feeling satisfied for longer Less hunger between meals Fewer cravings Less frequent thoughts about food
Not everyone experiences these effects to the same degree.
Some people notice a substantial change in appetite.
Others notice a more gradual difference.
The aim is not to remove the need to eat altogether.
Adequate nutrition remains important even when appetite is substantially reduced.
Which Leads to More Weight Loss?
This is one of the most common questions when comparing Wegovy and Mounjaro.
There is now direct clinical trial evidence comparing tirzepatide with semaglutide.
The SURMOUNT 5 trial included 751 adults with obesity who did not have type 2 diabetes.
After 72 weeks, average body weight reduction was approximately:
20.2 per cent with tirzepatide
compared with
13.7 per cent with semaglutide
Participants received the maximum tolerated dose of tirzepatide, either 10 mg or 15 mg, or semaglutide at 1.7 mg or 2.4 mg.
That sounds like a straightforward answer, but there are important limitations.
The trial was funded by Eli Lilly, which manufactures tirzepatide.
It also compared tirzepatide against semaglutide doses up to 2.4 mg.
Since the trial was conducted, a higher 7.2 mg weekly Wegovy dose has been authorised in the UK for some adults with obesity.
Most importantly:
Clinical trial averages cannot predict what will happen to an individual patient.
One person may respond particularly well to semaglutide while another may respond better to tirzepatide.
Is Mounjaro Better Than Wegovy?
Not automatically.
The direct comparison trial found greater average weight reduction with tirzepatide than with the semaglutide doses studied.
But weight reduction is only one part of a prescribing decision.
A doctor also needs to consider:
Medical history Existing health conditions Current medication Previous treatment Side effects Pregnancy considerations Contraception Individual response Potential risks and benefits
The treatment that produces the greatest average weight loss in a study is not necessarily the most appropriate medicine for every individual patient.
Is Mounjaro Stronger Than Wegovy?
It is better not to describe one medicine simply as stronger than the other.
They are different medicines and their doses cannot be directly compared.
For example:
5 mg of tirzepatide does not equal 5 mg of semaglutide.
The milligram figures relate to completely different active ingredients.
This is particularly important if someone is changing treatment.
You should never try to calculate an equivalent dose yourself.
How Often Are They Taken?
Mounjaro is generally administered as a once weekly injection.
Injectable Wegovy is also generally taken once weekly.
Both medicines use gradual dose increases rather than beginning immediately at a higher treatment dose.
Mounjaro starts at 2.5 mg once weekly before increasing according to the authorised dosing schedule and clinical response.
Wegovy injection also starts at a low weekly dose and is gradually increased.
This gradual approach gives the body time to adjust and can help manage side effects.
Patients should not increase their dose early because they want faster weight loss.
Dose changes should follow the prescribing plan.
Does Wegovy Now Come as a Tablet?
Yes.
This is an important recent change.
In June 2026, the MHRA approved the UK's first GLP 1 tablet specifically for weight management.
The Wegovy tablet contains semaglutide and is taken once daily.
It begins at 1.5 mg daily before increasing through different dose levels where appropriate.
So Wegovy is no longer exclusively an injectable treatment.
When people compare Wegovy and Mounjaro, however, they are still often referring to the injectable versions.
What Is the New 7.2 mg Wegovy Dose?
Wegovy has also changed in another important way.
The MHRA approved a maximum weekly dose of 7.2 mg semaglutide for certain adults with obesity in January 2026.
A single dose 7.2 mg pen was subsequently approved in April 2026.
The 7.2 mg dose is specifically authorised for adults with obesity and does not apply to every person using Wegovy.
This does not mean everyone taking Wegovy should progress to 7.2 mg.
The appropriate dose remains a clinical decision.
Who May Be Considered for Wegovy or Mounjaro?
Eligibility depends on the medicine and individual circumstances.
BMI is one of the factors commonly considered.
For weight management treatment, authorised criteria can include adults with obesity as well as certain adults who are overweight and have an associated weight related health condition.
Other factors may include:
Blood pressure Cholesterol Type 2 diabetes Prediabetes Sleep apnoea Cardiovascular disease Current medicines Previous treatment
Meeting general eligibility criteria does not guarantee that treatment will be prescribed.
An individual clinical assessment is still required.
Read more:
Who Can Be Prescribed Weight Loss Medication in the UK?
Are NHS Criteria Different?
Yes.
This causes considerable confusion.
A medicine's licensed indication describes the circumstances in which it can potentially be prescribed.
Publicly funded NHS or Health and Social Care criteria can be narrower.
This means someone may potentially meet the licensed criteria for a medicine without qualifying for publicly funded treatment.
Northern Ireland is also introducing new specialist obesity pathways in stages.
For more information, read:
Can You Get Weight Loss Treatment on the NHS in Northern Ireland?
and
Weight Loss Injections in Northern Ireland: A Patient Guide
Do Wegovy and Mounjaro Have Similar Side Effects?
There is considerable overlap.
Common side effects can include digestive symptoms such as:
Nausea Diarrhoea Constipation Vomiting Abdominal discomfort Indigestion
Fatigue and dizziness can also occur in some patients.
In the SURMOUNT 5 comparison trial, gastrointestinal events were the most commonly reported adverse effects with both medicines and were mostly mild to moderate.
Side effects can be particularly noticeable when treatment begins or when the dose is increased.
Can Either Medicine Cause Pancreatitis?
Yes, although acute pancreatitis is uncommon.
In January 2026, the MHRA strengthened the warnings for GLP 1 receptor agonists and dual GLP 1 and GIP receptor agonists following reports of rare severe cases.
Symptoms can include:
Severe and persistent abdominal pain
which may spread towards the back and may occur alongside nausea or vomiting.
These symptoms require prompt medical assessment.
They should not simply be assumed to be ordinary digestive side effects.
Is There a Particular Eye Warning With Semaglutide?
There is an additional safety update worth knowing about.
The MHRA advises that semaglutide has been very rarely associated with non arteritic anterior ischaemic optic neuropathy, or NAION.
This condition can cause sudden, painless deterioration or loss of vision, typically affecting one eye.
Anyone experiencing sudden or significant vision loss while taking semaglutide should seek urgent medical attention.
Does Mounjaro Affect the Contraceptive Pill?
This is one important difference between the treatments.
Tirzepatide may reduce the effectiveness of oral contraception in some people when treatment begins or when the dose is increased.
Current MHRA advice recommends adding a barrier method such as condoms, or using a non oral method of contraception, for:
Four weeks after starting Mounjaro
and
Four weeks after each dose increase.
Anyone affected should discuss their contraception with an appropriate healthcare professional.
Can Wegovy or Mounjaro Be Used During Pregnancy?
GLP 1 based weight management medicines should not be used during pregnancy.
The MHRA currently advises allowing:
At least two months after stopping semaglutide before trying to become pregnant
and
At least one month after stopping tirzepatide.
If you are pregnant, planning pregnancy or think you may be pregnant, discuss your treatment with your clinician.
Can Either Medicine Make You Tired?
Yes.
Fatigue can occur during treatment.
However, tiredness may also result from:
Eating considerably less Dehydration Vomiting or diarrhoea Poor sleep Rapid weight loss Nutritional deficiencies Another medical condition
This is why persistent tiredness should not automatically be blamed on the medicine.
Read more:
Can Weight Loss Medication Make You Tired?
Can You Switch From Wegovy to Mounjaro?
Potentially.
However, switching should be clinically managed.
These medicines have different active ingredients, strengths and dosing schedules.
The MHRA advises people to speak to a healthcare professional before switching between GLP 1 related treatments.
Do not attempt to convert the dose yourself.
A clinician needs to consider when your last dose was taken, what dose you were using, side effects and why the treatment is being changed.
What If One Medicine Is Not Working?
Weight loss rarely continues at exactly the same rate indefinitely.
It is normal for progress to slow.
If weight appears to have plateaued, a clinician may review:
Your current dose Appetite Eating pattern Physical activity Weight trend Side effects Treatment adherence Other medical factors
Changing treatment is only one possible response.
A plateau does not automatically mean a medicine has stopped working.
Does a Higher Dose Always Mean Better Results?
No.
Different patients respond differently.
A higher dose may produce additional benefit for some people, but may also increase side effects.
The aim should not simply be to reach the highest available dose.
Dose decisions should reflect the patient's response, tolerability and individual clinical circumstances.
What Happens When You Stop Wegovy or Mounjaro?
The appetite reducing effects gradually decrease as the medicine leaves the body.
Some people notice:
Increased hunger Larger portions becoming easier to eat Increased food cravings More frequent thoughts about food
Weight regain can occur after treatment stops.
That is why longer term weight management planning remains important.
Read:
Do You Need to Taper Off Weight Loss Medication?
Is One Treatment Cheaper?
Private prices vary according to the healthcare provider, pharmacy, formulation and dose.
A starting price may also change as treatment progresses.
This means it is sensible to understand the likely longer term cost rather than simply comparing the cheapest introductory price.
Price should also not determine which prescription medicine a doctor chooses.
Clinical suitability needs to come first.
Read our guide:
How Much Does Private Weight Loss Treatment Cost in Northern Ireland?
Wegovy Versus Mounjaro: Which Is Right for You?
There is no universal answer.
Wegovy contains semaglutide and acts on GLP 1.
Mounjaro contains tirzepatide and acts on both GLP 1 and GIP.
Direct clinical trial evidence found greater average weight reduction with tirzepatide than semaglutide at the doses studied, but that does not mean tirzepatide is automatically the right treatment for every patient.
Medical history, other medicines, contraception, side effects, individual risk and personal circumstances all matter.
The decision should be made following an individual clinical assessment rather than simply choosing whichever medicine is currently most popular.
How Does Keltoi Wellness Approach Weight Management?
Keltoi Wellness provides a doctor led telehealth weight management service for adults in Northern Ireland.
Patients provide relevant health, medication and weight information through the assessment process to support the doctor's clinical review.
A patient may have a preference for a particular treatment.
However, patient preference does not determine the prescription.
Any decision about whether prescription treatment is appropriate, which medicine should be considered and what dose should be used is made independently by the treating doctor.
The Bottom Line
Wegovy and Mounjaro are both used in medical weight management, but they are different prescription medicines.
Wegovy contains semaglutide and acts on the GLP 1 receptor.
Mounjaro contains tirzepatide and acts on both GLP 1 and GIP receptors.
Both can reduce appetite and support weight reduction in appropriately selected patients.
Both can cause side effects.
Neither is suitable for everyone.
And although clinical studies can help us understand the average differences between treatments, they cannot tell an individual patient which medicine is right for them.
The appropriate choice should always be based on an individual clinical assessment.
Keltoi Wellness provides doctor led remote weight management support to adults across Northern Ireland.
All prescribing decisions are made independently by the treating doctor following an individual assessment.
Health information provided by Keltoi Wellness is for general education and does not replace individual medical advice, diagnosis or treatment.