Wegovy vs Mounjaro: What's the main difference?

Wegovy and Mounjaro are 2 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.

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.

According to clinical trials:

• Mounjaro was found to help people lose up to 22.5% of their starting body weight when taking the highest maintenance dose of 15mg, once a week, for 72 weeks
• Wegovy was found to help people lose on average 21% of their starting weight over 72 weeks on the maintenance dose of 7.2mg

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.

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

Wegovy and Mounjaro are both weight loss injections that reduce appetite and help patients feel fuller for longer. They belong to the same group of medications, called glucagon-like peptide (GLP-1) receptor agonists, which mimic natural hormones that regulate hunger, blood sugar, and metabolism.

They work in similar ways as they both:

• send signals to the brain to reduce hunger and food cravings
• slow the emptying of food from the stomach, prolonging fullness after meals
• support better control of blood sugar by improving how the body processes sugars and fats

The main differences are:

• Wegovy contains semaglutide, which mimics 1 hormone: GLP-1
• Mounjaro contains tirzepatide, which mimics 2 hormones: GLP-1 and GIP (glucose-dependent insulinotropic polypeptide)
• GIP is thought to enhance the effects of GLP-1, which may make Mounjaro more effective for some patients

Because the active ingredients are different, patients may respond differently to each treatment. One may work better than the other, or one may cause side effects that the other does not. A doctor can help decide which option is most suitable.

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 2 hormones with its dual agonist formula, it has the potential to cause more side effects.

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

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.

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

There may be more side effects of these medications not listed here. For a full list of potential side effects, 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 7.2mg.

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 get or are concerned about side effects at higher doses.

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.

Wegovy and Mounjaro contain different active ingredients, so they have different doses. This does not make Wegovy stronger or weaker, it just means the doses cannot be compared directly. The dosage schedules for both medications are set up for effective weight loss. Mounjaro mimics 2 hormones, so it may be more potent or have a slightly stronger effect.

You can switch from Wegovy to Mounjaro, or from Mounjaro to Wegovy, if one is not working for you or you are not getting the results you wanted. Your GP or online doctor will be able to advise you further. If you can take Wegovy, you’re most likely able to take Mounjaro, and vice versa.

At ZAVA, our weight loss service makes it easier to switch GLP-1 medication within just 7 days. This means that, if your request for a different GLP-1 medication is approved, you will need to wait just 7 days before taking the next medication. For example, if you were previously taking Wegovy and one of our doctors approves the switch to Mounjaro, you would need to come off Wegovy for 7 days before starting Mounjaro. The dosage you start from will depend on the dose you were on for Wegovy. The same process applies if you were switching from Mounjaro to Wegovy.

Here is an example of the doses if you are switching from Mounjaro to Wegovy:

Here is an example of the doses if you are switching from Wegovy to Mounjaro:

Mounjaro to Wegovy dose conversion chart

The chart below shows the dosage schedules of both Mounjaro and Wegovy.

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 medication, 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)

The patient information leaflet contains more information on who may not be suitable for each medication. Your doctor will also make sure that it’s safe to take Wegovy or Mounjaro before prescribing it to you.

Whether you choose Mounjaro or Wegovy, the medication increases in price as you increase your dose. Here are the prices for both treatments at ZAVA, which include your prescription, weight loss support, and the option to message a doctor for free through your account at any time.

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 weight loss tablets if injectable options do not 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 a 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 8.1% of their starting weight after 56 weeks.

Alternative injections: Nevolat (generic liraglutide) and Ozempic

Nevolat (liraglutide) is a prescription weight loss injection given daily that reduces your appetite and contains the active ingredient liraglutide. Liraglutide has been proven to help people lose an average of 8% of their starting weight after 56 weeks.

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 is not 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.

Wegovy and Mounjaro are both effective weight loss injections and contain a similar active ingredient, working in almost the same way. Mounjaro has shown higher weight loss results, with 22% weight loss over 72 weeks on average, compared to 21% on 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 or if you’d prefer a cheaper option. If you meet the requirements for both and are suitable for both, the choice depends on which you’d prefer to try.

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