Mounjaro vs Wegovy For Weight Loss

What’s the difference and which one is best for you?

Mounjaro and Wegovy are both weight loss injections that can help you lose and maintain a healthy weight. Both are popular treatments, although there are similarities and differences between the two, such as their active ingredients, dosage schedules, and effectiveness. Here we compare Mounjaro vs Wegovy for weight loss, so you can decide which treatment is right for you.

Dr Babak Ashrafi Clinical Lead for Service Development

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 15 May 2024

How do Mounjaro and Wegovy 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

What are the differences between Mounjaro and Wegovy?

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.

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 - the maintenance dose

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 only has 1. 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).

Weeks Mounjaro dosage Wegovy dosage
1-4 2.5mg 0.25mg
5-8 5mg (or you stick with this as a maintenance dose) 0.5mg
9-12 7.5mg 1mg
13-16 10mg (or you stick with this as a maintenance dose) 1.7mg
17-20 12.5mg 2.4mg maintenance dose (from week 17 onwards) - no more dose escalation needed
21+ 15mg (maximum maintenance dose) Continue on 2.4mg
At a glance: wegovy dosage guide
At a glance: Mounjaro dosage guide

Effectiveness

Mounjaro and Wegovy have both been tested in clinical trials and proven to be effective weight loss medications. For Mounjaro, the clinical trial was carried out over 72 weeks with the following results on each maintenance dose:

  • those taking 5 mg lost 16% of their starting weight
  • those taking 10 mg lost 21.4% of their starting weight
  • those taking 15 mg lost 22.5% of their starting weight

For Wegovy, the clinical trial was carried out over 68 weeks. On average, at the maintenance dose of 2.4mg, people lost 15% or more of their starting weight.

The clinical trials ran for a slightly different amount of time (Mounjaro: 72 weeks, Wegovy: 68 weeks), so it’s hard to say which one is the most effective as you’d need to compare results over the same number of weeks. During all clinical trials, patients also followed a diet and exercise plan, which all patients must do when taking any weight loss treatment. Weight loss injections can also work slightly differently for everyone, so you may find that one works better for you, or that you tolerate one with fewer side effects. With either medication, you can lose a significant amount of weight, especially compared to dieting and exercising alone.

Cost

Mounjaro and Wegovy have different costs, although they sit in a similar price range. They also both have different prices depending on which dose you’re currently taking. Below are 2 tables with the price for each Mounjaro and Wegovy dose at Superdrug Online Doctor*.

Wegovy dose Price for 1 pen (4 weeks of treatment)
0.25mg £195.00
0.5mg £195.00
1mg £195.00
1.7mg £245.00
2.4mg £295.00
Mounjaro dose Price for 1 pen (4 weeks of treatment)
2.5mg £215.00
5mg £215.00
7.5mg £225.00
10mg £225.00
12.5mg £245.00
15mg £245.00

*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.

What are the similarities between Mounjaro and Wegovy?

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

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.

A guide to where to inject Wegovy
A guide to where to inject Mounjaro

Titration

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.

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

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:

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

Common side effects:

Mounjaro Wegovy
  • allergic reaction, including itching, rash, or eczema
  • dizziness
  • stomach pain
  • low blood pressure
  • indigestion
  • bloating
  • burping
  • gas
  • reflux
  • heartburn
  • hair loss
  • tiredness (fatigue)
  • injection site reactions
  • an increased level of lipase (a pancreatic enzyme) in the bloodstream
  • indigestion
  • dizziness
  • upset stomach
  • hair loss
  • burping
  • gas
  • bloating
  • inflamed stomach (gastritis)
  • heartburn or reflux
  • gallstones
  • injection site reactions
  • low blood sugar in diabetic patients

Uncommon side effects:

Mounjaro Wegovy
  • an increased level of amylase (a pancreatic enzyme) in the bloodstream
  • gallstones
  • pain at the injection site
  • cholecystitis (infection of the gallbladder)
  • increased levels of calcitonin in the bloodstream (a hormone regulating calcium levels in your blood)
  • a delay in the emptying of the stomach
  • fast heartbeat
  • an increase in pancreatic enzymes in the bloodstream

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

Can you switch from Wegovy to Mounjaro?

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 5 weeks after your last dose of Wegovy before you can start the Mounjaro dosage schedule, and you’ll always start at the lowest dose. The same goes for switching from Mounjaro to Wegovy, you’ll just need to wait 5 weeks in between.

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. Taking them at the same time could also lead you to lose weight too quickly, which can cause health problems.

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 5 weeks. 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.

Which one is right for me?

Wegovy and Mounjaro are both effective and safe weight loss injections that can be used alongside 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:

  • 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.

Mounjaro and Wegovy FAQs

Is Wegovy or Mounjaro more effective?

Wegovy and Mounjaro both have promising results in clinical trials:

As both studies were not carried out over the same number of weeks, and the studies weren’t set up to compare the 2, it’s difficult to say whether one is more effective than the other as there isn’t a direct comparison.

Is Wegovy or Mounjaro more expensive?

Wegovy and Mounjaro sit at a similar price range but have different prices depending on the dose. If you get Wegovy or Mounjaro prescribed through Superdrug Online Doctor, you’ll end up paying about the same overall, depending on how long you take the treatment for.

Wegovy costs less for the lower doses (£195.00 for 0.25mg and 0.5mg) but the maintenance dose is £295.00 per pen. Mounjaro costs more for the lower doses (£215.00 for 2.5mg and 5mg), but the other maintenance doses cost less than Wegovy (£225.00 for 10mg and £245.00 for 15mg).

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.

Sources

Patient Reviews