Mounjaro vs Wegovy: What’s the Difference?
19 August, 2026

Mounjaro vs Wegovy: What’s the Difference?

Mounjaro vs Wegovy: What’s the Difference?

Mounjaro and Wegovy are two prescription medicines used to support weight management. Both can reduce appetite and help you feel fuller, but they contain different active ingredients and work slightly differently.

So, is one better than the other? Not necessarily. The right medicine depends on your health, how well you tolerate it and what your prescriber recommends.

This guide explains the main differences in straightforward terms.

Important: This article provides general information, not medical advice. Mounjaro and Wegovy are prescription-only medicines. Never start, stop, change your dose or switch medicines without speaking to a qualified healthcare professional.

Mounjaro vs Wegovy at a glance

Mounjaro Wegovy
Active ingredient Tirzepatide Semaglutide
Type of medicine Dual GIP and GLP-1 receptor agonist GLP-1 receptor agonist
How often is it taken? Once a week Usually once a week by injection
How is it taken? Injection Injection, with a tablet form now authorised in the UK
Approved for weight management? Yes, for eligible adults Yes, for eligible adults
Common side effects Mostly digestive Mostly digestive

Both medicines should be used alongside appropriate nutrition, physical activity and ongoing healthcare support.

What is Mounjaro?

Mounjaro is the brand name for tirzepatide.

It works on receptors for two naturally occurring hormones:

  • GIP, or glucose-dependent insulinotropic polypeptide

  • GLP-1, or glucagon-like peptide-1

This is why Mounjaro is described as a dual GIP and GLP-1 receptor agonist.

It can help reduce hunger and make you feel fuller after eating. In the UK, Mounjaro is licensed for weight management in eligible adults and for treating type 2 diabetes.

Mounjaro is normally taken as a weekly injection. Treatment begins at a lower dose, which may be increased gradually under medical supervision.

What is Wegovy?

Wegovy is the brand name for semaglutide.

Unlike Mounjaro, it works on the GLP-1 receptor only. It can still reduce appetite, increase fullness and slow the rate at which food leaves the stomach.

Wegovy has traditionally been supplied as a weekly injection. In June 2026, the MHRA also authorised a once-daily Wegovy tablet for weight management in eligible UK adults. Availability may differ, and the tablet has specific instructions for how it should be taken.

Wegovy should not be confused with Ozempic or Rybelsus. These products also contain semaglutide, but their UK licences are different.

How do they help with weight loss?

Both medicines affect the signals involved in hunger, fullness and blood-glucose regulation. This may make it easier to eat smaller portions and maintain a reduced-calorie diet.

The main difference is simple:

  • Wegovy works on the GLP-1 receptor.

  • Mounjaro works on both GIP and GLP-1 receptors.

This difference may affect average weight-loss results, but it cannot predict exactly how one person will respond.

Which produces more weight loss?

The SURMOUNT-5 clinical trial directly compared tirzepatide with injectable semaglutide in 751 adults with obesity who did not have type 2 diabetes.

After 72 weeks, the average change in body weight was:

  • 20.2% reduction with tirzepatide

  • 13.7% reduction with semaglutide

Tirzepatide produced greater average weight loss in this particular trial.

However, these percentages are not guaranteed results. The trial looked at a specific group of people, used maximum tolerated doses and included dietary and physical-activity support.

It also compared tirzepatide with injectable semaglutide—not the newer Wegovy tablet.

The results do not mean Mounjaro is automatically the best option for everyone. Your medical history, other medicines, side effects, access and personal response all matter.

Do Mounjaro and Wegovy have similar side effects?

Yes. Their side effects often overlap, especially those affecting digestion.

Common side effects can include:

  • Nausea

  • Diarrhoea

  • Constipation

  • Vomiting

  • Stomach discomfort

  • Reduced appetite

These effects can be more noticeable when treatment begins or after a dose increase. They may improve as your body adjusts.

Speak to your prescriber if symptoms are persistent, difficult to manage or preventing you from eating and drinking normally.

Vomiting and diarrhoea can cause dehydration. Seek medical advice if you cannot keep fluids down, feel unusually weak or show signs of dehydration.

You should seek urgent medical attention if you experience severe and persistent stomach pain, particularly if it spreads to your back or happens alongside vomiting. This can be a sign of pancreatitis, which requires urgent assessment.

People taking semaglutide should also seek urgent help if they experience sudden sight loss or a rapid change in their vision.

Always read the patient information leaflet supplied with your exact medicine.

Pregnancy and contraception

Neither Mounjaro nor Wegovy should be used during pregnancy.

Current MHRA advice says semaglutide should be stopped at least two months before trying to become pregnant. Tirzepatide should be stopped at least one month beforehand.

Tirzepatide may also reduce the effectiveness of oral contraception when treatment begins and after a dose increase.

People taking the contraceptive pill are advised to use an additional barrier method, such as condoms, for four weeks after starting Mounjaro and for four weeks after every dose increase. Alternatively, discuss a non-oral contraceptive method with a healthcare professional.

Contact a healthcare professional promptly if you become pregnant while taking either medicine.

Can you switch between Mounjaro and Wegovy?

Only under medical guidance.

The medicines use different dosing schedules and should not be treated as directly interchangeable. Do not overlap doses or try to calculate an equivalent dose yourself.

Your prescriber can explain how and when to switch safely if changing medicine is appropriate.

Nutrition still matters

Mounjaro and Wegovy can make eating less feel easier. However, a much smaller appetite can also make it more difficult to get enough protein, fibre, vitamins and minerals.

There is no special “Mounjaro diet” or “Wegovy diet”. The aim is to make the food you can manage as nutritionally useful as possible.

Try to prioritise:

  • Protein-rich foods such as eggs, fish, chicken, yoghurt, tofu, beans and lentils

  • Fruit and vegetables

  • Higher-fibre carbohydrates such as oats, wholegrain bread and potatoes

  • Moderate portions of healthy fats

  • Regular fluids throughout the day

Smaller, balanced meals may feel more manageable than one large plate.

How NYN can support your nutrition

When appetite is reduced or preparing a balanced meal feels difficult, NYN GLP-1 Journey Support provides a convenient way to add protein, fibre and micronutrients to your day.

One labelled 50g serving provides:

  • 25.5g protein

  • 5.9g fibre

  • 23 vitamins and minerals

  • 170.8 calories

  • 10.6g carbohydrate

  • 2.3g sugars

  • 4.2g fat

NYN is nutritional support. It is not a medicine, does not replace a varied diet and does not make Mounjaro or Wegovy work more effectively.

Protein and fibre

NYN contains pea and rice protein alongside 3g of hydrolysed bovine collagen.

Protein contributes to the growth and maintenance of muscle mass. This makes protein an important part of your eating pattern during weight loss.

The formula also contains fibre from partially hydrolysed guar gum, inulin, resistant starch and acacia fibre.

Fibre should be introduced according to individual tolerance. If you are experiencing diarrhoea, significant bloating or symptoms linked to delayed stomach emptying, ask your clinician or dietitian whether a higher-fibre product is suitable for you.

Vitamins and minerals

Each serving contains the following 23 vitamins and minerals:

  • Vitamins A, C, D3, E and K2

  • Vitamins B1, B2, B3, B5, B6 and B12

  • Folate

  • Magnesium

  • Potassium

  • Calcium

  • Iron

  • Zinc

  • Selenium

  • Copper

  • Manganese

  • Iodine

  • Chromium

  • Molybdenum

These nutrients have recognised roles in normal health.

Depending on the individual nutrient, they contribute to areas including:

  • Normal energy-yielding metabolism

  • Reduction of tiredness and fatigue

  • Normal immune-system function

  • Maintenance of normal bones

  • Normal muscle function

  • Normal nervous-system and psychological function

  • Normal red-blood-cell formation and oxygen transport

  • Protection of cells from oxidative stress

  • Normal thyroid function

  • Normal macronutrient metabolism

These are established nutritional functions. They do not mean NYN treats medication side effects, prevents muscle loss or controls diabetes.

Additional ingredients

NYN also contains:

  • Hydrolysed bovine collagen

  • L-tyrosine

  • Lion’s Mane mushroom powder

  • L-theanine

  • Digestive enzymes

  • Lactobacillus rhamnosus and Bacillus coagulans

  • CDP-choline

  • Ginger extract

  • Coenzyme Q10 as ubiquinol

  • Buckwheat germ extract described as spermidine powder

These ingredients are included as part of the overall formula. Their presence alone should not be taken as proof that NYN treats nausea, constipation, digestive problems, cognitive symptoms or any medical condition.

How to prepare NYN

Preparing NYN is simple:

  1. Remove the cap.

  2. Add 250ml of cold water.

  3. Replace the cap.

  4. Shake well for 30 seconds.

You can also fill it with water and chill it in the fridge for an extra-refreshing drink.

NYN contributes to your daily fluid intake, but it is not an oral rehydration solution and should not be used to treat dehydration caused by vomiting or diarrhoea.

Because NYN contains bovine collagen, it is not suitable for vegans or vegetarians.

Pregnant or breastfeeding women, people taking warfarin or other anticoagulants, and anyone with kidney disease, a medical condition, a restricted diet or concerns about medicine interactions should speak to an appropriate healthcare professional before use.

So, which one is better?

There is no single answer that applies to everyone.

Mounjaro produced greater average weight loss than injectable Wegovy in one direct clinical trial. However, the most effective medicine on paper is not always the most suitable one for an individual.

Your prescriber will consider:

  • Your medical history

  • Other medicines you take

  • Previous treatment results

  • Side effects

  • Dose tolerance

  • Pregnancy plans and contraception

  • NHS or private availability

  • Your ability to use the medicine correctly

The right choice is the medicine that is medically suitable, safe and manageable for you.

The bottom line

Mounjaro and Wegovy can both support weight management, but they are different medicines.

Mounjaro contains tirzepatide and works on both GIP and GLP-1 receptors. Wegovy contains semaglutide and works on the GLP-1 receptor.

Whichever medicine you have been prescribed, good nutrition remains important. NYN GLP-1 Journey Support offers a convenient source of protein, fibre and 23 vitamins and minerals for times when a conventional meal or snack feels difficult to manage.

It should be used as nutritional support—not as a replacement for medical care, a treatment for side effects or a promise of better weight-loss results.

Sources and further reading