Wegovy vs Mounjaro: Which Weight Loss Injection Is Best?

Wegovy and Mounjaro are two of the most recognised medical weight loss injections available in the UK. Both are prescription-only treatments used to support weight management in suitable patients, and both work by helping reduce appetite, increase fullness and support healthier eating patterns.

However, they are not the same medicine.

Wegovy contains semaglutide, a GLP-1 receptor agonist. Mounjaro contains tirzepatide, which acts on both GLP-1 and GIP pathways. This difference may affect weight loss results, side effects, suitability, dosing and cost.

If you are comparing Wegovy vs Mounjaro, the right choice depends on your medical history, BMI, weight-related health conditions, previous experience with weight loss treatments, tolerance of side effects, pregnancy plans, budget and long-term goals.

At Hannah London, medical weight loss injections are prescribed following a consultation, so your treatment can be chosen safely and appropriately.

Quick Fire Questions & Answers: Wegovy vs Mounjaro

Wegovy may be suitable for patients looking for a well-established semaglutide weight loss injection with a strong clinical evidence base.

Mounjaro may be suitable for patients who are eligible for tirzepatide and may benefit from a dual-action medicine that targets both GLP-1 and GIP pathways.

Clinical evidence suggests Mounjaro may lead to greater average weight loss than Wegovy for some patients. However, that does not automatically mean Mounjaro is better for everyone. Suitability, safety, side effects and ongoing support matter just as much as the number on the scales.

The safest way to decide is through a medical consultation.

What is Wegovy?

Wegovy is the brand name for semaglutide when used for weight management. It is a once-weekly injection prescribed for eligible patients living with obesity or overweight with weight-related health concerns.

Semaglutide works by mimicking a natural hormone called GLP-1. This hormone is involved in appetite regulation, fullness, digestion and blood sugar control.

Wegovy can help people feel fuller for longer, reduce hunger and support lower calorie intake. It is designed to be used alongside lifestyle changes such as improved nutrition, physical activity and long-term behaviour support.

Wegovy is not the same as Ozempic, although both contain semaglutide. In the UK, Wegovy is the semaglutide brand used for weight management, while Ozempic is used for type 2 diabetes.

What is Mounjaro?

Mounjaro is the brand name for tirzepatide. It is also a once-weekly injection used for suitable patients as part of a medically managed weight loss plan.

Tirzepatide works on two hormone pathways: GLP-1 and GIP. These hormones help regulate appetite, fullness, digestion, insulin response and blood sugar.

Because Mounjaro acts on two pathways rather than one, it is sometimes described as a dual-action weight loss injection. This dual action is one reason clinical evidence suggests Mounjaro may result in greater average weight loss than semaglutide for some patients.

However, response varies. Some patients do very well on Wegovy. Others may respond better to Mounjaro. Some may not be suitable for either.

Wegovy vs Mounjaro: comparison table

Active ingredient

Wegovy contains semaglutide.

Mounjaro contains tirzepatide.

Medicine class

Wegovy is a GLP-1 receptor agonist.

Mounjaro is a dual GIP and GLP-1 receptor agonist.

How often is it taken?

Both Wegovy and Mounjaro are usually taken once weekly by injection.

Main effect

Both treatments help reduce appetite and increase feelings of fullness.

Mounjaro may have a broader metabolic effect because it targets both GLP-1 and GIP.

Expected weight loss

Both can support clinically meaningful weight loss in suitable patients.

Mounjaro may lead to greater average weight loss than Wegovy for some people, although results vary.

Side effects

Both can cause digestive side effects such as nausea, vomiting, diarrhoea, constipation, reflux, bloating and stomach discomfort.

Best for

Wegovy may suit patients looking for a semaglutide-based treatment with established use in weight management.

Mounjaro may suit patients who are eligible for tirzepatide and looking for a dual-action option.

Decision needed

Both require a medical consultation before prescribing.

Which works better for weight loss: Wegovy or Mounjaro?

When comparing Wegovy vs Mounjaro for weight loss, clinical evidence suggests that Mounjaro may lead to greater average weight loss than Wegovy in some patient groups.

This does not mean every patient should automatically choose Mounjaro.

A better question is: which treatment is safest, most suitable and most sustainable for you?

Weight loss injection results depend on many factors, including:

Starting weight
BMI
Medical history
Dose tolerance
Dietary habits
Activity levels
Sleep
Stress
Alcohol intake
Consistency
Side effects
Follow-up support
Whether the treatment is used correctly

A patient who tolerates Wegovy well and follows a strong lifestyle plan may have better long-term results than someone who starts Mounjaro but struggles with side effects or stops treatment early.

The most effective treatment is the one that is clinically suitable and sustainable.

How do Wegovy and Mounjaro work?

Both Wegovy and Mounjaro affect appetite and fullness signals.

They can help reduce hunger, slow digestion and make it easier to feel satisfied with smaller portions. This can support a calorie deficit, which is needed for weight loss.

However, they are not appetite “off switches”. You still need to eat appropriately, maintain hydration, prioritise protein, support muscle mass and develop sustainable habits.

Wegovy mechanism

Wegovy mimics GLP-1, a hormone that helps regulate appetite and blood sugar. It can help you feel fuller after meals and reduce cravings or constant hunger.

Mounjaro mechanism

Mounjaro acts on GLP-1 and GIP receptors. This dual action may support appetite regulation, blood sugar control and metabolic response in a slightly different way from semaglutide.

Wegovy vs Mounjaro side effects

Wegovy and Mounjaro have similar side effect profiles because both affect digestion and appetite hormones.

Common side effects may include:

Nausea
Vomiting
Diarrhoea
Constipation
Stomach pain
Bloating
Indigestion
Reflux
Reduced appetite
Feeling full quickly
Tiredness
Headache
Injection site redness or itching
Hair shedding during weight loss

These side effects are often most noticeable when starting treatment or increasing the dose. For many people, they reduce as the body adjusts.

However, symptoms should still be monitored. Persistent vomiting, diarrhoea or poor fluid intake can lead to dehydration.

Wegovy vs Mounjaro dosing

Both Wegovy and Mounjaro are usually started at a low dose and increased gradually. This helps the body adjust and may reduce side effects.

You should not increase your dose faster than advised. You should also not take extra doses to speed up weight loss.

Wegovy dosing

Wegovy is usually started at a low weekly dose and gradually increased over several weeks until a maintenance dose is reached, depending on tolerance and clinical guidance.

Mounjaro dosing

Mounjaro is also started at a low weekly dose and increased gradually. Dose increases should be based on medical advice, treatment response and side effect tolerance.

Can you switch from Wegovy to Mounjaro?

Some patients may consider switching from Wegovy to Mounjaro if they are not achieving expected results, have reached a plateau, or are looking for a different treatment option.

However, you should not switch between GLP-1 medicines without medical advice.

Switching requires careful consideration of:

Your current dose
How long you have been taking treatment
Side effects
Weight loss progress
Blood sugar status
Other medications
Medical history
Pregnancy plans
Timing of the next dose
Whether a washout period is needed

Switching incorrectly can increase the risk of side effects or reduce treatment effectiveness.

Can you switch from Mounjaro to Wegovy?

Yes, some patients may switch from Mounjaro to Wegovy under medical supervision. This may be considered if Mounjaro is not tolerated, cost becomes an issue, supply changes, or Wegovy is more suitable based on medical history.

Again, this should only happen with guidance from a qualified prescriber.

Wegovy vs Mounjaro cost

The cost of Wegovy and Mounjaro can vary depending on:

Dose
Clinic or provider
Consultation structure
Whether follow-up is included
Supply availability
Prescription and dispensing costs
Whether lifestyle support is included
Whether you are treated privately or through the NHS

In many private settings, Mounjaro may cost more than Wegovy at certain doses, although pricing can change. The cheapest option is not always the safest or most appropriate option.

When comparing cost, look at the full service, not just the pen price. A responsible programme should include medical screening, prescription oversight, side effect advice, progress review and long-term support.

At Hannah London, current pricing should be checked directly through the clinic’s weight loss injection pages or during consultation, as costs can change over time.

Wegovy vs Mounjaro availability in the UK

Both Wegovy and Mounjaro are available in the UK as prescription medicines for suitable patients.

Access may differ depending on whether you are seeking NHS treatment or private treatment. NHS eligibility criteria can be stricter and may involve BMI thresholds, weight-related health conditions and service availability.

Private prescribing still requires proper medical checks. These medicines should not be bought from social media, beauty salons, informal sellers or unregulated websites.

A legitimate provider should always complete a consultation before prescribing.

Who is eligible for Wegovy or Mounjaro?

Eligibility depends on individual assessment. Your prescriber may consider:

BMI
Weight-related health conditions
Age
Medical history
Current medications
Diabetes status
Blood pressure
Cholesterol
Pregnancy or breastfeeding
Contraception
History of pancreatitis
Gallbladder disease
Kidney or liver concerns
Eating disorder history
Previous weight loss treatments
Readiness to make lifestyle changes

You may be eligible for one treatment but not the other. You may also need further checks before treatment is prescribed.

Wegovy vs Mounjaro for patients with diabetes

Both semaglutide and tirzepatide are also used in diabetes care under specific brands and indications. If you have type 2 diabetes, treatment choice must be reviewed carefully, especially if you take insulin or medicines that can lower blood sugar.

Do not start, stop or change diabetes medication without medical advice.

If you have diabetes and are considering weight loss injections, your clinician may need to review your blood sugar control, eye health, kidney function and existing medication plan.

Wegovy vs Mounjaro if you are planning pregnancy

GLP-1 medicines should not be used during pregnancy, while breastfeeding, or just before trying to conceive.

If you are planning pregnancy, you must discuss this with your prescriber before starting treatment. Semaglutide and tirzepatide have different recommended stopping periods before trying for a baby.

Mounjaro may also affect the reliability of the oral contraceptive pill during certain stages of treatment, particularly after starting or increasing the dose. If this applies to you, your clinician may recommend additional or alternative contraception.

This is an important part of a safe medical consultation.

Which is better for appetite control?

Both Wegovy and Mounjaro can reduce appetite and help people feel full sooner.

Some patients report stronger appetite suppression on Mounjaro, while others feel well controlled on Wegovy. Individual response varies, and stronger appetite suppression is not always better if it leads to nausea, poor nutrition, dehydration or difficulty eating enough protein.

The goal is not to stop eating. The goal is to support controlled, balanced eating in a way that improves health and can be maintained.

Which is better if you are worried about side effects?

If you are concerned about side effects, the best choice depends on your medical history and tolerance.

Both Wegovy and Mounjaro can cause digestive symptoms. Some patients tolerate one better than the other, but this cannot always be predicted before starting.

A careful prescriber may recommend:

Starting slowly
Monitoring symptoms
Delaying dose increases if needed
Reviewing hydration and nutrition
Adjusting treatment if side effects are difficult
Stopping treatment if it is not safe

You should never continue severe side effects just because you want faster results.

Which is better for long-term weight maintenance?

Long-term weight maintenance depends on more than the injection.

Wegovy and Mounjaro can both support weight loss while you are taking them. However, if eating habits, activity levels, sleep, stress and lifestyle patterns do not change, weight regain can happen after stopping.

A good medical weight loss programme should help you build:

Balanced meals
Protein intake
Better portion control
Hydration habits
Strength training or movement
Sleep routines
Reduced alcohol intake where relevant
Follow-up accountability
Realistic long-term goals

The medication is a tool. The plan around it is what helps make results sustainable.

Can Wegovy or Mounjaro help with “quick weight loss”?

These treatments can produce meaningful weight loss, but they should not be used as quick-fix injections before a holiday, wedding or event.

They are prescription medicines designed for eligible patients with clinical need. They require assessment, dose progression, monitoring and follow-up.

Using them casually or without support can increase the risk of side effects, poor nutrition, dehydration and unsafe weight loss patterns.

Who should not use Wegovy or Mounjaro?

Wegovy or Mounjaro may not be suitable if you:

Are pregnant
Are breastfeeding
Are trying to conceive soon
Have had pancreatitis
Have certain severe digestive conditions
Have a history of serious allergic reaction to GLP-1 medicines
Have complex diabetes medication needs
Have severe kidney or liver disease
Have an active eating disorder
Are underweight or not clinically eligible
Are unable to attend follow-up or monitor side effects

This is not a complete list. Suitability must be assessed by a medical professional.

Is Mounjaro better than Wegovy?

Mounjaro may lead to greater average weight loss than Wegovy in some studies, but that does not mean it is automatically better for every patient.

Mounjaro may be a strong option if you are eligible, medically suitable and able to tolerate it.

Wegovy may be a better option if semaglutide is more appropriate for your medical profile, treatment goals, budget or previous medication history.

The “best” injection is the one that fits your health, not just the one that appears strongest on paper.

Is Wegovy safer than Mounjaro?

Both are prescription medicines with potential side effects and risks. Neither should be described as risk-free.

Wegovy has been used for weight management for longer than Mounjaro, while Mounjaro has shown strong weight loss results and is now widely discussed in medical weight management.

Safety depends on:

Correct prescribing
Patient suitability
Dose progression
Medical history
Side effect monitoring
Medication interactions
Follow-up support
Use alongside lifestyle advice

A consultation is the safest way to compare them properly.

Wegovy vs Mounjaro: how to choose

You may be better suited to Wegovy if:

You are eligible for semaglutide
You prefer a GLP-1-only option
Your clinician feels semaglutide suits your health profile
You have previously responded well to semaglutide
You are looking for a well-established weight management injection

You may be better suited to Mounjaro if:

You are eligible for tirzepatide
You may benefit from dual GLP-1 and GIP action
Your clinician feels it suits your medical profile
You are looking for a treatment that may offer greater average weight loss
You can tolerate the treatment and follow-up plan

You may not be suited to either if there are medical contraindications, safety concerns, pregnancy plans, certain medications or unrealistic expectations.

Why consultation matters before choosing Wegovy or Mounjaro

Comparing Wegovy vs Mounjaro online can be helpful, but it cannot replace a medical consultation.

A consultation allows your clinician to review:

Your BMI and weight history
Your medical background
Current medication
Weight-related conditions
Diabetes status
Family history
Pregnancy or contraception needs
Previous treatment attempts
Side effect risk
Lifestyle habits
Your goals and expectations

This helps ensure the recommendation is safe, realistic and personalised.

Medical weight loss injections at Hannah London

Hannah London offers medical weight loss injections for eligible patients, including Wegovy and Mounjaro.

Our approach is clinically led and personalised. Rather than simply choosing the most popular injection, we assess your suitability, discuss your goals, explain the differences between treatments and help you understand what to expect.

A medical consultation can help determine whether Wegovy, Mounjaro or another approach is most appropriate for you.

If you are comparing Wegovy vs Mounjaro and want clear medical guidance, book a consultation with Hannah London to discuss your options safely.