Wegovy and Mounjaro are two popular and effective injectable weight loss treatments that are currently available in the UK. While they both help to manage appetite and make you feel fuller, there are some key differences between Mounjaro and Wegovy.
This guide will compare the two treatments, explaining their differences as well as any similarities. It will also cover the potential side effects of Mounjaro and Wegovy, alongside the costs for both treatments.
How do Mounjaro and Wegovy work?
Mounjaro and Wegovy both work by mimicking the glucagon-like peptide-1 (GLP-1) hormone. This hormone is found naturally in your body and helps to manage how hungry you feel.
While Wegovy only mimics GLP-1, Mounjaro also activates glucose-dependent insulinotropic peptide (GIP) receptors. GIP receptors work in a similar way to GLP-1 receptors and are responsible for insulin secretion as well as fat metabolism.
GLP-1 binds with receptors in your brain and activates them, reducing hunger levels and making you feel fuller. The active ingredient in Wegovy (semaglutide) and Mounjaro (tirzepatide) mimics the effects of this natural hormone.
Both Mounjaro and Wegovy also increase insulin release when blood sugar levels are high. This helps to regulate blood sugar levels and prevents large fluctuations, which can trigger food cravings.
Differences between Wegovy and Mounjaro
The key difference between Wegovy and Mounjaro is that Mounjaro also mimics GIP hormones as well as GLP-1. This is known as a ‘dual mechanism of action’.
By activating receptors for both hormones, Mounjaro has an additional way in which it supports weight loss compared to Wegovy.
Active ingredients
While Wegovy and Mounjaro’s active ingredients have similar effects on your body, they are different compounds.
Semaglutide (in Wegovy) is a GLP-1 receptor agonist. This means it activates GLP-1 receptors in the brain.
Tirzepatide (in Mounjaro) is a GLP-1 and GIP receptor agonist. This means it activates both GLP-1 and GIP receptors in the brain.
Mounjaro has a greater potential effect for weight loss due to this dual mechanism of action.
Dosages
The dosage schedules for Mounjaro and Wegovy are different as they contain different active ingredients. The table below shows the dose taken each month, as well as the increase from one dose to the next.
| Weeks |
Wegovy Dose |
Mounjaro Dose |
| 1-4 |
0.25mg |
2.5mg |
| 5-8 |
0.5mg |
5.0mg |
| 9-12 |
1.0mg |
7.5mg |
| 13-16 |
1.7mg |
10.0mg |
| 17-20 |
2.4mg |
12.5mg |
| 21+ |
2.4mg |
15.0mg |
To find out more information about dosages, refer to our dosage guides:
Always consult with your treatment provider about the treatment dosages and never make changes to your dose without their approval.
Similarities of Mounjaro and Wegovy
Taking injections
Mounjaro and Wegovy are injectable weight loss pens that are administered into the patient’s body. The medication is injected once a week for both treatments.
Both Mounjaro and Wegovy should be injected into the upper legs, stomach (abdomen) or upper arms. It is recommended that the first dose is injected into the stomach as there are fewer nerves and more fat compared to the other injection sites. This makes it easier and less painful to administer.
You should rotate where you inject after each dose to avoid any irritation to the skin around the injection site.
Read more about how to administer the medications:
Frequency of treatment
Both Mounjaro and Wegovy are administered once a week. You should take medication on the same day and time every week. This ensures that there is a consistent amount of medication in your body.
Each pen contains four doses of the medication, so it will last for four weeks.
If you forget to take a dose at the same time each week, refer to the patient information leaflet for the medication you are taking for advice on how to safely return to the treatment schedule.
Is Wegovy or Mounjaro more effective?
Wegovy and Mounjaro are both proven to be effective at promoting weight loss in clinical studies.
A trial showed that patients taking Wegovy (semaglutide) had up to a 14.9% reduction in body weight after 68 weeks of treatment.[1]
For Mounjaro (tirzepatide), a trial showed that patients had up to a 22.5% reduction in body weight after 72 weeks of treatment.[2]
It is important to note that neither Wegovy nor Mounjaro directly decrease body weight by themselves. Treatment needs to be supported with healthy diet and lifestyle decisions, such as eating a balanced, calorie-controlled diet and regular exercise for the best results.
Also, individuals’ bodies can respond to treatment differently and experience varying side effects from either medication. This can lead to varying results from patient to patient on both Wegovy and Mounjaro.
Your treatment provider will advise you on the most appropriate medication for you specifically.
Side Effects: Wegovy vs Mounjaro
Both Wegovy and Mounjaro may cause side effects, like many prescription medications. Experiencing side effects is more likely when first starting treatment. It is also more likely when increasing the dose of either medication, as the amount of the active ingredient also increases.
Wegovy and Mounjaro have similar ‘very common’ side effects. This means they may affect more than 1 in 10 people. These side effects include:
- nausea
- vomiting
- diarrhoea
- constipation
- abdominal (stomach) pain
- hypoglycaemia (low blood sugar)
- headaches
- fatigue
For more detailed information on side effects, read our in-depth guides:
Refer to the patient information leaflet that is included with both injectable weight loss pens for a full list of side effects.
Contact your treatment provider if you have any concerns about side effects.
Is Mounjaro or Wegovy more affordable?
Mounjaro and Wegovy have comparable costs over the full course of treatment. However, they have different prices depending on the dose.
Mounjaro is slightly more expensive than Wegovy, particularly in the earlier stages of treatment. However, it may offer greater weight loss outcomes for some individuals, as it works through a dual mechanism of action. Mounjaro also has an additional maximum dose from week 21 onwards compared to Wegovy.
Refer to our product pages for the latest pricing information:
Frequently asked questions
Is Wegovy or Mounjaro better for weight loss?
Both Wegovy and Mounjaro have been clinically proven to be effective for weight loss. However, in recent trials, patients taking Mounjaro did lose slightly more body weight than those taking Wegovy, over a comparable timeframe.[1][2]
It is important to note that results may vary depending on the individual. Patients may tolerate treatment differently, so it is important to always consult with your treatment provider to ensure you are taking the most appropriate treatment.
Diet and exercise also have a significant impact on weight loss results with both medications. Getting the best outcome on Mounjaro or Wegovy depends on making healthy and sustainable improvements to your lifestyle.
Does Mounjaro or Wegovy have more side effects?
Mounjaro and Wegovy have similar side effects that you may experience. Side effects are more likely to occur when increasing the dose of both medications.
The patient information leaflet for each medication will detail the potential side effects that can occur while taking Mounjaro or Wegovy.
Different individuals may also experience side effects differently. This could be the frequency they experience them or the intensity.
Is Wegovy or Mounjaro safer for weight loss?
Both Wegovy and Mounjaro have been approved by the Medicines and Healthcare products Regulatory Agency (MHRA) in the UK for weight loss.
Wegovy and Mounjaro are both safe if you always use either medication exactly as instructed by your treatment provider.
Can you switch between Wegovy and Mounjaro?
Yes, you may switch from one medication to the other, but only under the guidance of your treatment provider.
You must also wait for several weeks when switching medications. This ensures that the medication has time to leave your body before you start on the other treatment. You will always start on the lowest dose when switching, no matter what dose you were on previously.
Your treatment provider may recommend changing medication if they believe an alternative is more appropriate for you.
Is Mounjaro or Wegovy better for me?
Whether Mounjaro or Wegovy is better for you will likely depend on your tolerance to the medication. Side effects may vary between individuals, so what works best for you might be different to someone else.
Your treatment provider can advise you on the best treatment for you specifically.
Will I get better results if I take Wegovy and Mounjaro together?
No. Do not take Wegovy and Mounjaro (or any other injectable weight loss pen) together.
Both medications work by targeting similar hormone pathways involved in appetite regulation, so taking both at the same time can significantly increase the risk of side effects. These can be serious and life-threatening.
Wegovy and Mounjaro were both designed to be used individually and have not been tested for safety or efficacy when combined in clinical studies.
Sources
1. Once-Weekly Semaglutide in Adults with Overweight or Obesity, 2021. [Accessed 05/08/2025]
2. Tirzepatide Once Weekly for the Treatment of Obesity, 2022. [Accessed 05/08/2025]