Wegovy vs Mounjaro: Which Is Better for Weight Loss?

Wegovy vs Mounjaro

This page compares Wegovy vs Mounjaro for weight loss. It explains in simple language how they work, what results you might expect, possible side effects, and how to access them safely in the UK.

Both medicines are prescription-only. They must not be bought from unregulated sources or promoted without a prescription. Speak to a pharmacist, your GP or complete a clinical assessment if you want to know if either medicine might suit you.

What are Wegovy and Mounjaro?

• Wegovy is the brand name for semaglutide. It acts like GLP-1, a natural hormone that helps you feel full. Wegovy is licensed in the UK for weight management in adults who meet clinical criteria.
• Mounjaro is the brand name for tirzepatide. It acts on two hormones (GIP and GLP-1) that affect appetite and blood sugar. In the UK, Mounjaro is licensed for type 2 diabetes. Its use for weight loss is being studied and routine NHS access for weight loss is limited.

Both are given as an injection under the skin (subcutaneous) once a week. They are used together with diet and physical activity changes.

How they work — simple explanation

• Wegovy (semaglutide): mimics GLP-1. It slows stomach emptying and reduces appetite so you eat less.
• Mounjaro (tirzepatide): acts on GIP and GLP-1. This can reduce appetite and improve how the body handles sugar and fat.

Both reduce hunger and can help with weight loss. Clinical studies show one drug may cause more average weight loss than the other, but results vary between people.

Typical results from studies

• Clinical trials show both medicines help people lose significant weight when combined with diet and exercise.
• In head-to-head research, tirzepatide (Mounjaro) produced larger average weight loss than semaglutide (Wegovy) over the study periods. This does not mean it is right for everyone.
• Individual response varies. Some people lose a lot of weight, others less.

Long-term safety and what happens after stopping treatment are still being studied. Your clinician will discuss the current evidence when advising you.

Side effects and safety

Common side effects for both medicines include:

• Feeling or being sick (nausea, vomiting)
• Diarrhoea or constipation
• Stomach pain or indigestion
• Tiredness or dizziness

Most side effects are mild to moderate and improve over weeks. Starting at a low dose and increasing slowly helps reduce side effects.

Important safety points:

• These medicines can cause low blood sugar (hypoglycaemia) if used with other diabetes medicines. Your clinician will adjust other medicines if needed.
• They are not suitable if you have a personal or family history of certain thyroid cancers (for example, medullary thyroid carcinoma) or certain endocrine disorders. Discuss your history with a clinician.
• They must not be used in pregnancy or while breastfeeding. Women who could become pregnant should use contraception while taking them.
• Tell your clinician and pharmacist about all other medicines you take. Interactions are possible.

Seek immediate medical help for severe abdominal pain, persistent vomiting, signs of an allergic reaction (swelling, difficulty breathing), or any severe reaction.

Who should NOT take them

Do not take Wegovy or Mounjaro if you:

• Are pregnant, planning pregnancy, or breastfeeding.
• Have a personal or family history of certain thyroid cancers.
• Have had an allergic reaction to semaglutide or tirzepatide.
• Have other serious medical conditions where these drugs are unsuitable.

A clinician will assess your full medical history before prescribing.

NHS access and cost in the UK

• Wegovy is available on the NHS for some people when they are referred to specialist weight management services and meet local criteria. Services and eligibility vary by area.
• Mounjaro (tirzepatide) is licensed in the UK for type 2 diabetes. Routine NHS use of Mounjaro for weight loss is limited. Access for weight management may be possible in specialist clinics or clinical trials.
• Both medicines are only available on prescription from a clinician. They are not sold over the counter.

For NHS advice and eligibility, speak to your GP or a specialist weight management service. You can also speak to a pharmacist or complete a clinical assessment to explore options.

Comparison table: Wegovy vs Mounjaro

Practical points if you are prescribed one

• Read the patient information leaflet and follow dosing instructions.
• Clinicians usually start at a low dose and increase slowly to reduce side effects.
• Use with a reduced-calorie diet and increased physical activity as advised by your healthcare team.
• Regular follow-up is important to check response and side effects.
• Do not stop suddenly without advice. Stopping may lead to weight regain.

Questions people often ask

Q: Which is better, Wegovy or Mounjaro?
A: Clinical trials show Mounjaro (tirzepatide) may produce greater average weight loss than Wegovy (semaglutide) over the study periods. But "better" depends on your health, how you tolerate side effects, and your personal goals. Both are available privately — our clinicians can assess you and recommend the right option.

Q: What is better for weight loss, Wegovy or Mounjaro?
A: Studies suggest tirzepatide leads to more weight loss on average, but the right choice is individual. Book a private weight-loss assessment and a clinician will help you decide.

Q: Can anyone get these drugs on the NHS?
A: No. Wegovy is available for some people via specialist services. Mounjaro’s routine use for weight loss on the NHS is limited. Local services and criteria differ. Ask your GP or local weight management service.

Q: Are these medicines safe long term?
A: Long-term safety is still being studied. Doctors weigh benefits and risks for each person. Regular review is needed.

Q: What if I have type 2 diabetes?
A: Mounjaro is licensed for type 2 diabetes. Both drugs affect blood sugar. If you have diabetes, your clinician will adjust other medicines to avoid low blood sugar.

Q: How long will I stay on treatment?
A: This depends on your response and goals. Some people use them long term under medical supervision. Stopping often results in some weight regain if lifestyle changes are not maintained.

FAQs

• Are Wegovy and Mounjaro the same as Ozempic or semaglutide?
  Wegovy contains semaglutide. Ozempic is another brand of semaglutide used mainly for diabetes. Doses and licensed uses differ.
• Are they over-the-counter?
  No. They are prescription-only medicines.
• Can I get them without blood tests?
  Your clinician will usually check your health, blood sugar and other factors before and during treatment.

Where to get reliable help

• Talk to your GP or a specialist weight management service. They know NHS criteria and local options.
• Speak to a pharmacist for medicine questions and safety advice.
• Consider a structured service that offers diet, activity and psychological support alongside medication.

Useful UK sources include the NHS, NICE and the MHRA. For medicine details, clinically trained staff use the BNF.

If you want to explore this option, complete a clinical assessment or speak to a pharmacist to check if you might be suitable and to discuss risks and benefits.

Internal resources:

• Complete a clinical assessment — https://form.thechemistlive.com/assessment/weight-loss
• How prescription weight-loss medicines work — https://www.thechemistlive.com/services/weight-loss
• Speak to a pharmacist — https://www.thechemistlive.com/contact