Wegovy vs Mounjaro: What's the Main Difference?

Wegovy and Mounjaro are two prescription weight loss injections that work in similar ways, but there are some key differences, including active ingredient, effectiveness, availability, and price. In this guide, we examine the pros and cons of Mounjaro vs Wegovy for weight loss to help you get a general idea of which treatment might be right for you.

Brenda Ikeji

Medically reviewed by

Dr Brenda Ikeji

Last reviewed: 17 Jan 2025

Key takeaways

  • Wegovy is a prescription weight loss injection that is injected weekly. It contains the active ingredient semaglutide, and is available on prescription in the UK for overweight adults with weight-related health conditions or adults with obesity. Wegovy is manufactured by Novo Nordisk.
  • Mounjaro is also a prescription weight loss injection that is injected weekly. It contains the active ingredient tirzepatide, and is available in the UK to treat either type 2 diabetes or as a weight loss treatment. Mounjaro is manufactured by Eli Lilly and is called Zepbound in the US.
  • Wegovy and Mounjaro are both available for prescription in the UK and can be prescribed through our online doctor service. Find out more about weight loss treatments available at ZAVA.
  • Both treatments work best when used as part of a wider weight loss programme that might include healthy dietary changes and exercise suited to you. Other medications and ways to lose weight are also available.

What is Wegovy?

Wegovy, also known as semaglutide, is an injectable weight loss medication for overweight adults with weight-related health conditions, or adults with obesity. Taken once a week, it works by mimicking a hormone – glucagon-like peptide-1 (GLP-1) – which targets areas of the brain that regulate appetite.

Wegovy is prescription-only, and is taken as part of a weight management programme that also includes healthy dietary changes and exercise.

Five boxes of wegovy each showing their different dosages

What is Mounjaro?

Mounjaro is also taken once a week as an injection. It contains the active ingredient tirzepatide. Like Wegovy, it mimics the GLP-1 hormone. Tirzepatide is slightly different though, as it also mimics glucose-dependent insulinotropic polypeptide (GIP), which makes it a type of medication known as a dual agonist.

GIP is another hormone that is released after eating, which helps regulate blood sugar levels and improves how your body uses fat and sugar from your diet. This hormone is also believed to help regulate appetite.

In the UK, Mounjaro was already available on prescription to help treat adults with type 2 diabetes but has now been approved for use as a weight-loss drug for those who are obese, or overweight with weight-related health problems.

Photo of Mounjaro kwickpen 5 mg with the pen beside it, a lid, and solution

Both Mounjaro and Wegovy are available through ZAVA's weight loss service:

How do Wegovy and Mounjaro work?

Both medications suppress your appetite and make you feel fuller for longer, but they work in slightly different ways due to their different active ingredients.

Wegovy contains semaglutide, which works by mimicking a hormone called GLP-1 which is released after eating, making you feel full. It does this by sending signals to the parts of your brain that control appetite and hunger. This can regulate your appetite and aid with weight loss alongside changes to diet and exercise.

The active ingredient in Mounjaro is tirzepatide, which is a dual agonist, meaning that it mimics GLP-1 and GIP. Alongside the benefits of being a GLP-1 agonist, GIP is thought to further enhance the effects of GLP-1 (reduced appetite and feeling fuller for longer).

Mounjaro and Wegovy also slow the emptying of food from the stomach, so food will be broken down more slowly and you’ll feel full for longer. It also improves the body’s ability to metabolise (break down) sugars and fats from food.

Both of these treatments should be used alongside a healthy diet and exercise regime for the best possible results.

You can switch between weight loss injections with the help of a doctor. Find out more about switching from Wegovy to Mounjaro.

What is the difference between Wegovy and Mounjaro?

The main difference between Wegovy and Mounjaro is their active ingredients. The tirzepatide in Mounjaro works in a slightly different way to semaglutide in Wegovy, as it affects more processes in the body by mimicking 2 hormones instead of 1. Some things, such as side effects, are similar but may be very common or common depending on the medication.

The difference in active ingredients is important when considering Wegovy vs Mounjaro as your body may react differently to each ingredient. This could mean:

  • you might be sensitive to a particular ingredient in one injection
  • one medication might prove more or less effective than the other for you
  • one may have specific side effects for you while the other doesn’t

The choice of Wegovy or Mounjaro can be a complex decision, but we’ve put together a list of the main similarities and differences to help you make the best choice for you.

Comparing Wegovy vs. Mounjaro

Wegovy Mounjaro
What is the active ingredient?

Semaglutide, a GLP-1 receptor agonist

Tirzepatide, a GLP-1 and GIP receptor agonist

How does it work?

By reducing your appetite

By reducing your appetite

How much weight can you lose?

Up to 15%

Up to 22.5%

How often do you take it?

Once a week

Once a week

What is the maintenance dosages?

2.4mg

5mg, 10mg, or 15mg

How soon do you reach the maximum dosage?

5 months

6 months

Is it prescription only?

Yes.

Yes.

How much is it per month?

From £139.00

From £139.00

Like all medications, Mounjaro and Wegovy can have some side effects. However, these won’t affect everyone who uses them and your dose will be increased slowly to minimise your chances of getting them.

Wegovy vs Mounjaro for weight loss

Mounjaro and Wegovy have both been through rigorous tests and comparisons. Mounjaro studies have proven that the new injection for weight loss is a little more effective than Wegovy, although more studies need to take place to accurately compare them.

Which is better for weight loss, Wegovy or Mounjaro?

According to clinical trials:

Mounjaro and Wegovy both have great results from clinical trials although it’s important to note that they have been tested for a slightly different number of weeks.

If you’d like to learn more about patient experiences and results on these medications, view our Wegovy Before & After and Mounjaro Before & After guides.

Ultimately, your doctor will decide which drug is best for you. Both injections work well for weight loss, as long as you follow the right Mounjaro or Wegovy dosage schedules alongside a healthy diet and exercise plan.

“Although Mounjaro and Wegovy are both effective weight loss treatments, Mounjaro can help you lose a higher percentage of your starting body weight on average. However, Mounjaro does have more reported side effects, so if you’re concerned about your sensitivity to treatment, Wegovy may be a better option.

A switch may be recommended if your treatment isn’t working as expected, or if you have an allergy to one of medications. You should never switch medications without your doctor’s advice.”

Brenda Ikeji
Dr Brenda Ikeji Medical Editor

Which has fewer side effects: Mounjaro or Wegovy?

Wegovy and Mounjaro work in almost the same way, so they have similar side effects, mostly related to the stomach. However, because Mounjaro mimics two hormones with its dual agonist formula, it has the potential to cause more side effects.

Not everyone experiences side effects of weight loss medication, and you can reduce your risk of potential side effects by following your dosage plan carefully.

We have created guides on the side effects of both Wegovy and Mounjaro, so you can learn more about what to expect while taking the medication and how to manage them. You can also speak to your GP or online doctor if you’re struggling with side effects.

An up-to-date list of side effects for Wegovy and Mounjaro can be found in the patient information leaflets that come with these medications. As they are both relatively new treatments, more side effects may be added as more people use the medication. If you get a side effect that’s not listed on the medication, speak to your doctor and report it to the Yellow Card Scheme.

Mounjaro and Wegovy are black triangle drugs. This means a black triangle appears after their brand name, which happens because a medication is new or is being used for a new reason or in a different way (e.g. injected rather than taken orally). Black triangle drugs are monitored more closely.

Here is a breakdown of the different side effects you can experience with Wegovy vs. Mounjaro:

Serious side effects

Wegovy Mounjaro
Common

complications of diabetic eye disease if you have diabetes

-

Uncommon

inflamed pancreas (acute pancreatitis)

inflamed pancreas (acute pancreatitis)

Rare

serious allergic reaction (anaphylaxis)

serious allergic reaction (anaphylaxis)

If you think you may be having an allergic reaction to either Mounjaro or Wegovy, please seek immediate medical attention.

Uncommon side effects

Wegovy Mounjaro
  • fast heartbeat
  • an increase in pancreatic enzymes in the bloodstream
  • a delay in the emptying of the stomach
  • bloating
  • increased levels of amylase in the blood (a pancreatic enzyme)
  • gallstones
  • injection site pain
  • cholecystitis (an infection of the gallbladder)
  • increased levels of calcitonin in the bloodstream (a hormone that helps to regulate calcium levels in your blood)
  • Very common side effects

    Wegovy Mounjaro
  • headache
  • feeling sick (nausea)
  • being sick (vomiting)
  • stomach pain
  • constipation
  • diarrhoea
  • feeling weak or tired
  • feeling sick (nausea)
  • diarrhoea
  • vomiting
  • constipation
  • Common side effects

    Wegovy Mounjaro
  • dizziness
  • upset stomach or indigestion
  • burping or gas
  • bloating
  • inflamed stomach (gastritis)
  • heartburn or reflux
  • gallstones
  • hair loss
  • injection site reactions
  • allergic reaction, such as itching, rash or eczema
  • dizziness
  • low blood pressure
  • stomach pain
  • indigestion
  • bloating
  • burping or gas
  • reflux or hearburn
  • hair loss
  • tiredness
  • injection site reactions
  • increased levels of lipase in the bloodstream (a pancreatic enzyme)
  • For further information see the patient information for Mounjaro and Wegovy.

    Wegovy and Mounjaro dosage charts

    Both Wegovy and Mounjaro have similar dosage schedules, though the quantities of the active ingredients (semaglutide and tirzepatide) are different.

    The Wegovy dosage schedule is increased every 4 weeks. You’ll start at the lowest dose (0.25mg) before gradually making your way to the maintenance dose of 2.4mg.

    Different Wegovy dosages for injection once per week: 0.25mg, 0.5mg, 1mg, 1.7mg, 2.4mg

    Mounjaro is also increased every 4 weeks, increasing up to a maximum dose of 15mg. However, you can choose to stay at the lower maintenance doses of 5mg and 10mg if you feel like those doses work well enough for you and you experience or are concerned about side effects at higher doses.

    Explaining Mounjaro Dosage options: start (2.5mg), continue (5mg), and additional dose (7.5mg, 10mg, 12.5mg, 15mg)

    Your ZAVA online doctor (or GP or other medical practitioner) will advise you about your Mounjaro or Wegovy dosage, and when you should move up to taking a higher dose of your medication.

    You can also find out more about this in the patient information leaflet that comes with your medication.

    Is Wegovy stronger than Mounjaro?

    Wegovy and Mounjaro contain different active ingredients, so they have different doses. This doesn’t make Wegovy stronger or weaker, it just means the doses can’t be compared directly. The dosage schedules for both medications are set up for effective weight loss.

    Switching from Wegovy to Mounjaro

    You may be able to switch from Wegovy to Mounjaro, and vice versa, if one isn’t working for you or you aren’t getting the results you wanted. Your GP or online doctor will be able to advise you further.

    When switching between weight loss injections, you’ll need to begin at the starting doses for each medication, regardless of what dosage you’ve reached on your current injection. You must also wait at least 5 weeks between the last dose of your current injection and the first dose of your new one, so your body has time to safely get rid of any remaining medication.

    It is vital to consult a medical professional before making any changes to your weight loss medication.

    Mounajro to Wegovy dose conversion chart

    The chart below shows the dosage schedules of both Mounjaro and Wegovy which can be useful to know when comparing them.

    Weeks Wegovy (mg) Mounjaro (mg)
    1-4 0.25 (starting dose) 0.25 (starting dose)
    5-8 0.5 5 (maintenance dose)
    9-12 1 7.5
    12-16 1.7 10 (maintenance dose)
    17-20 2.4 (maintenance dose) 12.5
    21+ 2.4 (maintenance dose) 15 (maintenance dose)

    Can you take Wegovy and Mounjaro together?

    No, you should not take Mounjaro and Wegovy at the same time. They both contain a GLP-1 receptor agonist, so taking both at the same time could be dangerous and will increase the risk of serious side effects and severe illness. Ask your doctor for more advice about which one might suit you best or how to switch from one to the other.

    Who should not take Mounjaro and Wegovy?

    You should not take either Mounjaro or Wegovy if:

    • you’re pregnant, plan to become pregnant, or are breastfeeding
    • you have had a serious allergic reaction to any of the ingredients in either pen

    If you become pregnant while using either drug, you should stop treatment and speak to your doctor right away.

    In addition, you should tell your doctor if you have:

    • ever had problems with your pancreas or kidneys
    • type 2 diabetes and a history of diabetic retinopathy (a diabetic eye disease)

    For a full list of reasons why you may not be able to take either medication, please check the patient information leaflets for Mounjaro and Wegovy. Your doctor will also make sure that it’s safe to take Wegovy or Mounjaro before prescribing it to you.

    How much do Wegovy and Mounjaro cost?

    Both of these weight loss medications start at roughly the same price per month when obtaining your treatment through ZAVA. Whether you choose Mounjaro or Wegovy, the medication increases in price as you increase your dose.

    Wegovy prices:

    Pack Size Price
    Wegovy 0.25 mg - 4 dose(s) - 1 pen £139.00
    Wegovy 0.5 mg - 4 dose(s) - 1 pen £169.00
    Wegovy 1 mg - 4 dose(s) - 1 pen £169.00
    Wegovy 1.7 mg - 4 dose(s) - 1 pen £224.00
    Wegovy 2.4 mg - 4 dose(s) - 1 pen £269.00

    Mounjaro prices

    Pack Size Price
    Mounjaro 2.5 mg - 1 pen - 4 dose(s) £139.00
    Mounjaro 5 mg - 1 pen - 4 dose(s) £139.00
    Mounjaro 7.5 mg - 1 pen - 4 dose(s) £169.00
    Mounjaro 10 mg - 1 pen - 4 dose(s) £189.00
    Mounjaro 12.5 mg - 1 pen - 4 dose(s) £204.00
    Mounjaro 15 mg - 1 pen - 4 dose(s) £204.00
    Starter Bundle 2.5 and 5 mg - 2 pens - 8 dose(s) £275.00
    Starter Bundle 2.5, 5 and 7.5 mg - 3 pens - 12 dose(s) £439.00

    What is an alternative to Wegovy and Mounjaro?

    Though Mounjaro and Wegovy are popular weight loss treatments, there are several other alternative medications available in the UK. These include:

    Weight Loss Pills

    Some people may choose to opt for weight loss tablets if the injectable options don’t suit them.

    Most weight loss tablets contain the active ingredient orlistat. It works by reducing the amount of fat absorbed from food by around a third. You can buy generic orlistat online with ZAVA. This 120mg medication needs to be taken with any meals containing fat (up to 3 times a day). Studies show that it’s effective in helping people lose 5% or more of their starting weight after 12 weeks than dieting alone.

    You can also buy branded orlistat treatments, such as Xenical and alli. Xenical contains the same dose as unbranded orlistat, so it can also help you lose 5% or more of your starting weight after 12 weeks when following a healthy diet and exercise program.

    While Xenical and orlistat require a prescription, alli can be bought over the counter. This is because it contains a lower dose of orlistat (60mg instead of 120mg). Keep in mind that alli is less effective for weight loss than prescription weight loss tablets as it contains half the dose per tablet.

    Mysimba is another private prescription weight loss pill that reduces your appetite and helps control cravings when taken daily, with a maximum maintenance dose of 2 tablets, twice a day. Its active ingredients are bupropion and naltrexone. Clinical trials have found that Mysimba can help people lose an average of 8.1% of their starting weight after 56 weeks.

    Alternative injections: Saxenda and Ozempic

    Saxenda (Liraglutide) is a prescription weight loss injection administered daily that reduces your appetite and contains the active ingredient liraglutide. Saxenda has been proven to help people lose an average of 8% of their starting weight after 56 weeks. It’s currently out of stock long-term, but generic liraglutide will be available soon.

    Ozempic is a prescription-only injection treatment for type 2 diabetes. The active ingredient in Ozempic is semaglutide – which is the same as Wegovy. Ozempic can also help with weight loss off-label (this is when a doctor prescribes a treatment for something it isn’t licensed for). ZAVA does not prescribe type 2 diabetes treatments off-label.

    If you’re uncertain about which weight loss treatment is right for you, get in touch with your GP or online doctor.

    In the meantime, here’s an overview of the weight loss medications discussed above to help you compare the options:

    Medication Type Active Ingredient How it works How often to take it
    Orlistat Pill Orlistat Prevents fat absorption 3 times daily, with each meal
    Xenical Pill Orlistat Prevents fat absorption 3 times daily, with each meal
    Mysimba Pill Bupropion-Naltrezone Reduces appetite Twice daily
    Wegovy Injection Semaglutide Reduces appetite Weely
    Saxenda Injection Liraglutide Reduces appetite Daily
    Mounjaro Injection Tirzepatide Reduces appetite Weekly
    alli Pill Orlistat Prevents fat absorption 3 times daily with each meal
    Start a Request for Weight Loss Treatment With Free Medical Check-ins & Weight Loss Support

    Frequently asked questions

    Which is safer, Mounjaro or Wegovy?

    Wegovy (semaglutide) has a slightly better safety profile when compared to Mounjaro (tirzepatide). Clinical studies have shown that Wegovy is associated with fewer side effects and less people stopping treatment due to adverse events. The margins of these results are very slim however, with Wegovy only having around 3% less side effects and rates of people stopping than Mounjaro.

    If you’re concerned about the side effects of treatment, you should speak to your doctor about the best choice of drug for you.

    Can my doctor prescribe Mounjaro or Wegovy for weight loss?

    Both Wegovy and Mounjaro can be prescribed by a weight management specialist service, which you’ll need to be referred to by your GP. Some GPs are also receiving training to prescribe weight loss injections, but this is a limited service that may not be available in your area. Ask your GP, or request treatment online today from ZAVA.

    Are Wegovy and Mounjaro available to buy online?

    Wegovy and Mounjaro are available to request online from ZAVA. Our ordering process is hassle-free and discreet:

    1. Start by answering some questions about your medical history and submitting a few photos. We’ll also ask about any similar medications you have used or are currently using.
    2. A registered doctor will review your answers to check that your preferred medication is suitable before they prescribe it to you. Otherwise, they may suggest an alternative treatment or give you further advice.
    3. If suitable, your weight loss medication will be prescribed and posted out to you.

    Our team of friendly doctors are here to support you at every stage of your weight loss journey. With ZAVA’s weight loss service, you can message a doctor for free, confidential weight loss advice through your account.

    Is it worth switching from Wegovy to Mounjaro?

    Switching from Wegovy to Mounjaro may be worth considering if you’re not seeing the desired results on your current treatment or are experiencing side effects that are difficult to manage. Since both medications have similar dosage schedules, most people can easily adapt to their new treatment plan. However, keep in mind that your weight loss results may be halted somewhat, since you need to wait at least 5 weeks for Wegovy to leave your system before starting Mounjaro. You will also have to restart your dosage schedule when you switch, beginning on the lowest dose again and increasing every 4 weeks.

    It’s important to note that while Mounjaro may offer better weight loss results for some people, it can come with a slightly higher risk of side effects than Wegovy.

    Before making any changes to your medication, you should always consult your GP or online doctor. They can help advise whether you’re suitable for another weight loss injection or whether you’d be better suited to other treatment types, like tablets.

    Can I stay on weight loss treatment forever?

    No. The point of weight loss treatment is to reach an ideal healthy weight and then come off your medication and maintain your new weight using lifestyle changes. Weight loss treatments are meant to be used long-term but if you aren’t losing weight then you should come off them and if you are losing weight you should eventually reach a low enough weight to come off them as well.

    When starting any weight loss treatment plan, you’ll be made aware that it’s important not to rely solely on the medication for success. Wegovy and Mounjaro are intended to be used in line with nutrition and exercise plans, promoting long-term lifestyle changes that help to support a healthy lifestyle.

    Conclusion: Which is best for weight loss, Wegovy or Mounjaro?

    Wegovy and Mounjaro are both effective weight loss injections that contain a similar active ingredient and work in almost the same way. Mounjaro has shown higher weight loss results, but this was over 72 weeks rather than 68 weeks like Wegovy.

    Mounjaro may be a better choice for you if you want to choose between a few maintenance doses, while Wegovy may be a better choice for you if you have an allergy to any of the ingredients in Mounjaro.

    If you meet the requirements for both and are suitable for both, the choice depends on which you’d prefer to try.

    Medically reviewed by

    brenda-ikeji.png Dr Brenda Ikeji

    Brenda studied medicine at St Georges University of London and has most recently worked in John Radcliffe Oxford University Hospitals, covering acute and general medicine. Before her medical career, Brenda was a medical scientist in microbiology working in several NHS diagnostic laboratories across England. She has also completed her Masters in Public Health and MSc in Genomic Medicine. She is currently a GP registrar.

    Last reviewed: 17 Jan 2025

    Sources

    EMC (2024). Mounjaro KwikPen 10mg solution for injection in pre-filled pen: https://www.medicines.org.uk/emc/product/15484, retrieved 24/07/2024

    EMC (2023). Wegovy 0.25 mg, FlexTouch solution for injection in pre-filled pen: https://www.medicines.org.uk/emc/product/13799/smpc#gref, retrieved 24/07/2024

    NHS (2023). Obesity treatment: https://www.nhs.uk/conditions/obesity/treatment/, retrieved 24/07/2024

    The New England Journal of Medicine (2015). A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management: https://www.nejm.org/doi/full/10.1056/nejmoa1411892, retrieved 24/07/2024

    The New England Journal of Medicine (2022). Tirzepatide Once Weekly for the Treatment of Obesity: https://www.nejm.org/doi/full/10.1056/NEJMoa2206038, retrieved 24/07/2024

    Wegovy.com (2023). https://www.wegovy.com/, retrieved 24/07/2024

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