Mounjaro vs Wegovy: Weight Loss Comparison

With the introduction of Wegovy 7.2mg, Mounjaro and Wegovy are now almost equally effective for weight loss. Both are once-weekly GLP-1 injections that can help you lose a significant amount of weight when combined with a reduced-calorie diet and regular physical activity. However, they contain different active ingredients, follow different dosing schedules, and may not be suitable for everyone.

In this guide, we compare Mounjaro and Wegovy side by side, including their effectiveness, side effects, doses, and costs, to help you understand which treatment may be the best fit for you.

Although Mounjaro and Wegovy are both weight loss injections that work in a similar way, there are some key differences. Below we look at those differences in more detail.

Active ingredient

Mounjaro contains tirzepatide, a dual agonist. As well as being a GLP-1 receptor agonist, it also mimics a second hormone called glucose-dependent insulinotropic peptide (GIP). This is thought to further enhance the effects of GLP-1. Wegovy contains semaglutide, which is a GLP-1 receptor agonist.

Although the active ingredient is different, both Mounjaro and Wegovy are appetite suppressants that send signals to your brain that you’re full and delay the emptying of your stomach. They can also help to regulate blood sugar levels, which may further help with cravings and energy levels.

Mounjaro vs Wegovy dosages

Mounjaro and Wegovy contain different active ingredients and so have different dosages.

Mounjaro has 6 doses, with a starting dose of 2.5mg, which you’ll take for 4 weeks. The other Mounjaro doses are:

• 5mg
• 7.5mg
• 10mg
• 12.5mg
• 15mg

The maintenance doses for Mounjaro are: 5mg, 10mg, or 15mg. You can stay on a lower maintenance dose if you’re happy with your results or get side effects at a higher dose.

Wegovy has 5 doses, with a starting dose of 0.25mg, which you’ll also take for 4 weeks. The other Wegovy doses are:

• 0.5mg
• 1mg
• 1.7mg
• 2.4mg
• 7.2mg - the maximum maintenance dose

Mounjaro vs Wegovy dosing schedule

Both Mounjaro and Wegovy follow a dosage schedule, although these are slightly different. Both have a starting and maintenance dose, although Mounjaro has 3 maintenance doses while Wegovy has 2. Below is a table with the Mounjaro and Wegovy dosage schedules, so you can see what dose you’d take at what time, and when to increase your dose (every 4 weeks).

At their highest maintenance doses, Mounjaro and Wegovy are almost equally effective for weight loss. In separate 72-week clinical trials, people taking Mounjaro 15mg weekly lost an average of 22.5% of their starting body weight, while those taking Wegovy 7.2mg lost an average of 21%. Although Mounjaro achieved slightly greater average weight loss, the difference is relatively small, making both treatments among the most effective weight loss medications currently available in the UK.

Lower maintenance doses also produce significant weight loss, although the amount generally increases as the dose is slowly increased:

It's important to remember that these results come from separate clinical trials rather than a head-to-head study. Participants in both studies also followed a reduced-calorie diet and increased their physical activity, which are essential parts of successful treatment.

Individual results can vary regardless of which medication you choose. Factors such as how well your body responds to treatment, whether you reach your maintenance dose, your lifestyle habits, and your adherence to the treatment plan can all influence how much weight you lose. For most people, both Mounjaro and Wegovy can produce substantially greater weight loss than lifestyle changes alone.

Mounjaro vs Wegovy side effects

Mounjaro and Wegovy can both cause side effects, although not everyone will get them. Each has similar side effects, but how often these occur may be different. Side effects of Wegovy and Mounjaro are most common when you first start taking it and after you’ve increased your dose. You should talk to your doctor if you get side effects that aren’t going away, or are affecting your daily life.

Very common side effects:

Common side effects:

Uncommon side effects:

For further information on the side effects of either medication, read the patient information for Mounjaro and Wegovy.

Mounjaro and Wegovy cause many of the same side effects because they both work by slowing stomach emptying and reducing appetite. For most people, the most common side effects are nausea, vomiting, diarrhoea, constipation, and stomach pain, particularly during the first few weeks of treatment or after increasing the dose.

The biggest difference is how often these side effects occur. In clinical trials, digestive side effects such as nausea, diarrhoea, and vomiting were generally reported slightly more often with Wegovy than with Mounjaro. Mounjaro was also associated with a lower rate of people stopping treatment because of side effects, suggesting that some people may find it easier to tolerate.

However, this does not mean Mounjaro is side effect-free. Some people experience more digestive symptoms with Mounjaro, while others tolerate Wegovy better. Everyone responds differently, and your experience may depend on factors such as your dose, how quickly you increase it, and your individual sensitivity to GLP-1 medications.

If you’re keen to avoid feeling sick (nausea) or stomach-related side effects is one of your main concerns, it is worth discussing this with your doctor before starting treatment. They can recommend the option that best suits your medical history and explain ways to reduce side effects, such as increasing your dose gradually, increasing hydration, eating smaller meals, and avoiding high-fat foods while your body adjusts to the medication.

Mounjaro vs Wegovy cost

Since the Mounjaro price increased in Autumn 2025, Wegovy is now cheaper at both lower and higher doses. See our cost comparison table for a full price comparison. Here are 2 tables with the price for each Mounjaro and Wegovy dose at Superdrug Online Doctor*:

*Please note these prices were correct at the time of writing this article, but are subject to change. You can check the Mounjaro or Wegovy product pages for the most up-to-date prices.

Manufacturer

Wegovy and Mounjaro have different manufacturers. Wegovy is manufactured by Novo Nordisk, a Danish company, while Mounjaro is manufactured by Eli Lilly, a North American company.

Novo Nordisk is also the manufacturer of Saxenda, one of the first weight loss medications available in the UK. This is currently long-term out of stock.

Mounjaro and Wegovy also have some similarities, which we’ll look into in more detail below.

How they work

Mounjaro and Wegovy are both weight loss injections that belong to a group of medications called glucagon-like peptide-1 (GLP-1) receptor agonists. They both work by mimicking GLP-1, a naturally occurring hormone that manages hunger levels. This:

• sends signals to your brain that you’ve eaten, making you feel full
• delays the emptying of your stomach, enhancing those feelings of fullness for longer periods of time

Administration

Both Mounjaro and Wegovy are multi-dose injectable pens which are self-administered. This means each pen contains the exact dose you’ll need, so you won’t need to draw up your own medication. Each pen has 4 doses, so lasts 4 weeks.

How to take it

Mounjaro and Wegovy should both be administered once a week, on the same day and time. They can also be taken with or without food. Taking either weight loss medication at the same time and day will improve its effectiveness and ensure there’s always a steady supply of the active ingredient in your body to keep your appetite suppressed.

For more information, download our guides on:

• Where to inject Wegovy
• Where to inject Mounjaro

Both Mounjaro and Wegovy have titrated doses to help manage side effects and allow you to adjust to the medication before reaching the maintenance dose.

The titration of Wegovy is: 0.25mg to 0.5mg to 1mg to 1.7mg to 2.4mg to 7.2mg.

The titration of Mounjaro is: 2.5mg to 5mg to 7.5mg to 10mg to 12.5mg to 15mg.

GLP-1 receptor agonists

Mounjaro and Wegovy are both GLP-1 receptor agonists. GLP-1 is usually released after you eat, sending a signal to your brain that you’re full and delaying the emptying of food from your stomach. The active ingredient in both weight loss treatments mimic GLP-1, helping you feel full, eat less and reduce your calorie intake, for more effective weight loss results.

Prescription-only

Mounjaro and Wegovy, like any weight loss injection, are only available via a prescription. A doctor needs to check your suitability before prescribing it, to make sure it's safe. At Superdrug Online Doctor, you can be prescribed Wegovy or Mounjaro if you meet the following criteria:

• a body mass index (BMI) of 30+, or a BMI of 27-30 and a weight-related medical condition or risk factor, such as prediabetes
• you don’t take any medications or have a medical condition that makes it unsafe to take weight loss medication
• you don’t have an allergy to any of the ingredients in the weight loss pen

Yes, you can switch from Wegovy to Mounjaro if you want to, although you’ll need to speak to your doctor first. You’ll also need to wait at least 7 days after your last dose of Wegovy before you can start the Mounjaro dosage schedule.

You might want to switch from Wegovy to Mounjaro if you:

• aren’t finding Wegovy is giving you the weight loss results you expected and you’re following a diet and exercise plan and taking Wegovy correctly (same time and day each week)
• are getting side effects from Wegovy that aren’t going away or getting better
• tried Wegovy in the past and it didn’t work for you
• were using Wegovy before Mounjaro was released, and now want to give Mounjaro a go instead

Can you take both medications at the same time?

No, you cannot take Mounjaro and Wegovy together. The same can be said for any prescription weight loss treatment. Taking Mounjaro and Wegovy at the same time could increase the risk of side effects, especially serious ones, as well as severe illness. This is also why you need to leave the appropriate gap between the two before starting new treatment as stated above.

Do I need to switch from Wegovy to Mounjaro?

You don’t need to switch from Wegovy to Mounjaro if you’re happy with your results on Wegovy and your side effects are well managed, unless you really want to. It’s important to note that switching could cause a delay in weight loss, as you’ll need to stop taking treatment for at least 1 week (7 days). Switching to another weight loss injection may also cause new side effects, as your body could react differently to a new active ingredient. Similarly, you may get less side effects. If you still aren’t sure, discuss this with your doctor.

Wegovy and Mounjaro are both effective and safe weight loss injections that can be used alongside a healthy diet and exercise to help you lose and maintain a healthy weight. Knowing which one is right for you comes down to a few things:

• preference – you may have a personal preference on which treatment you’d rather take
• suitability – one treatment may be safer for you to take than another because of your medical history, but a doctor can help you with this
• cost – although the cost of both treatments is similar, your budget may be better suited to one treatment than the other
• side effects – if you get side effects on one treatment and can’t continue, your doctor may recommend giving the other one a try instead
• availability – although every effort is made to keep both treatments available, Mounjaro and Wegovy are both popular medications and their manufacturers may not always be able to keep up with supply and demand

If you still aren’t sure which one is right for you, speak to your doctor. They can assess your suitability and answer any other questions you might have about each weight loss injection, but ultimately, the decision is up to you.

Alternative weight loss treatments

If you aren’t sure whether you want to take Wegovy or Mounjaro, or you’d rather take a weight loss tablet, Superdrug Online Doctor offers a range of alternative weight loss treatments. Below we look at each in more detail:

• Wegovy pill – an oral form of semaglutide, the same active ingredient in the Wegovy injection, that works in the same way, but is taken daily first thing in the morning on an empty stomach. It can be an effective option if you do not want to inject your medication, and it can result in an average weight loss of 16.6% after 64 weeks
• Foundayo – a once daily tablet containing the GLP-1 orforglipron which works to help you lose weight by suppressing your appetite and making you feel fuller for longer. Foundayo is another suitable alternative if you find GLP-1s to be effective but prefer oral medication to injections.
• orlistat – a generic 120mg tablet that works by reducing the amount of fat your body absorbs, which is removed in your stools. It contains the active ingredient orlistat and can be taken up to 3 times per day, with meals that contain some fat.
• Xenical – a branded treatment containing 120mg of the active ingredient orlistat. This also works to reduce the amount of fat your body absorbs, which is removed in your stools. It should be taken with meals that contain fat, up to 3 times per day.
• alli – an over-the-counter version of orlistat and Xenical, that contains the active ingredient orlistat but at a lower dose of 60mg. It works to reduce the amount of fat your body absorbs, which is removed in your stools. Alli can be taken up to 3 times per day, with a meal containing fat. Although you can get alli without a prescription, you’ll still need to answer some questions to make sure it’s suitable.
• Mysimba – a branded tablet that’s only available via a private prescription. It contains 2 active ingredients, naltrexone and bupropion, and is an appetite suppressant, working on the parts of your brain responsible for hunger and energy levels. Mysimba is taken every day, following a dosage schedule, up to a maintenance dose of 2 tablets, twice per day.

How long do you stay on Mounjaro or Wegovy to lose weight?

You can stay on Mounjaro or Wegovy for as long as you need to lose weight, as long as you don’t get serious or long-lasting side effects. You can choose to stop Mounjaro or Wegovy once you’ve reached your weight loss goals, or you can keep taking the medication to maintain your weight if your BMI is still high.

Where is the best place to inject Mounjaro or Wegovy?

The best place to inject Mounjaro or Wegovy is your stomach or upper legs. When injecting into your stomach, you just need to leave a 5cm gap from your belly button. You should also inject into a different piece of skin each week, even if you choose the same placement site.

Can you get Mounjaro or Wegovy on the NHS?

You can get Mounjaro and Wegovy on the NHS, but it’s usually only available through a tier 3 specialist weight loss management service. Your GP can refer you if you meet the criteria but there may be a long waiting list depending on where you live. Some GP’s are being trained to prescribe weight loss injections but this isn’t widely available at the moment.

Is Wegovy or Mounjaro safer?

Both Wegovy and Mounjaro are considered safe and effective weight loss medications when prescribed appropriately and used as directed. They have similar side effect profiles, but clinical trials suggest that fewer people stop taking Mounjaro because of side effects – 6.2% vs 7% for Wegovy 2.4mg. The right choice depends on your medical history, how well you tolerate treatment, and which side effects you are willing to accept.