Wegovy vs Mounjaro - Weight Loss Treatment Comparison in the UK

Weight loss injections are an ever-widening field. Over the past few years, Wegovy was one of the leaders of the pack, but since its release Mounjaro has taken the top spot.

But, does its popularity mean it is the right choice for you? In this article, we will cover two weight loss drugs – Mounjaro and Wegovy. We will compare their effects, their price and how you can switch from one to the other.

How Wegovy and Mounjaro Work

Mounjaro and Wegovy work in similar ways, but do have some differences that set them apart.

Both Wegovy and Mounjaro act as GLP-1 receptor agonists. This means they interact with receptors in your body that trigger when you eat. These receptors tell your brain when you’re full and help your body digest food properly. By triggering them, these medications allow you to feel fuller for longer, even when you eat less food.

Researchers first developed semaglutide, the active ingredient in Wegovy, to treat type 2 diabetes.

In type 2 diabetes, semaglutide can manage blood sugar levels. Regulators approved Ozempic, which contains semaglutide, for this use. For weight loss, it reduces appetite, helping patients eat less. Combined with exercise and dietary changes, this can lead to excellent results.

Patients take both Mounjaro and Wegovy as a weekly injection under the skin of the upper arm, thigh, or belly.

What Makes Mounjaro Different?

Both Wegovy and Mounjaro target GLP-1 receptors, which help control appetite and digestion. Mounjaro also targets GIP receptors, which play a role in how your body handles sugar and fat.

This dual action may improve blood sugar control, boost fat metabolism, and lead to greater weight loss for some people. However, it can also increase the chance of stronger side effects, especially during dose increases. Individual responses vary, while some people may see “better” results on Mounjaro, others find Wegovy suits them better.

Wegovy vs Mounjaro for Weight Loss – What Does the Research Say?

Head-to-Head Trial Results

One study found that patients lost an average of 22.9% of their body weight after 3.5 years on Mounjaro. In comparison, patients on Wegovy lost an average of 16.7% after 2 years. This suggests that Mounjaro may be more effective for weight loss in some patients.

However, Wegovy’s manufacturer, Novo Nordisk, recently announced a new strength for the Wegovy. This will make Wegovy a six-dose treatment with a weight loss profile similar to Mounjaro (about 20%).

Wegovy vs Mounjaro Side Effects and Safety

As with all medications, both Wegovy and Mounjaro have the potential to cause side effects in some patients. Because of how similar the medications are, they tend to have similar side effects.

Wegovy vs Mounjaro – Side Effects
Side Effect	Wegovy	Mounjaro
Nausea	✅	✅
Vomiting	✅	✅
Diarrhoea	✅	✅
Abdominal Pain	✅	✅
Constipation	✅	✅
Bloating	✅	✅
Flatulence	✅	✅

Please note this is not an exhaustive list of potential side effects, simply some of the most common ones. Clinical trials reported many other potential side effects, but they were far less common than those listed above. For more information on side effects, please read the Patient Information Leaflet for your medication.

How to Manage Side Effects

The side effects of both treatments are most noticeable when you increase your dose. They often settle after a short time, but there are steps you can take to help.

• Stay hydrated: drink enough water throughout the day to reduce nausea and support digestion.
• Eat smaller meals: more frequent portions are easier on the stomach.
• Avoid high-fat or spicy foods: during dose increases, as these can make digestion and nausea symptoms worse.

When you move up a dose, careful food choices can help reduce gastrointestinal side effects. Our Mounjaro and Wegovy recipes can ease your stomach and give you the nutrition you need.

If your side effects become difficult to deal with, or become concerning, please speak to a health professional.

Safety

Both medications require medical supervision. They are not suitable for everyone, and doctors will check your medical history and current health before prescribing.

Doctors may advise some people not to take these medications. This group includes those with conditions such as pancreatitis, severe digestive problems, or allergies to any ingredients.

Always follow your prescriber’s guidance and report any unexpected or severe symptoms.

Wegovy vs Mounjaro Cost in the UK

Currently, Wegovy costs slightly less than Mounjaro to start, and costs less to reach a maintenance dose. These prices are subject to change.

Wegovy Dose	Price	Mounjaro Dose	Price
0.25mg	£119	2.5mg	£128.98
0.5mg	£119	5mg	£139
1mg	£125	7.5mg	£169.99
1.7mg	£169	10mg	£189.99
2.4mg	£189	12.5mg	£204.95
–	–	15mg	£204.95

Wegovy vs Mounjaro UK Availability

Both Mounjaro and Wegovy are available in the UK, through both private prescriptions and the NHS.

However, both are only available on the NHS through specialised tier 3 weight loss services. The rules to qualify for these treatments are much stricter. For instance, to eligible for Mounjaro on the NHS, you need to have;

• A body mass index (BMI) of 40 or above
• At least 4 weight-related health conditions, such as;
  • High blood pressure
  • Type 2 diabetes
  • Cardiovascular disease
  • Obstructive sleep apnea
  • Dyslipidaemia

Even with long waits and strict rules, this can be a good option for patients who can’t afford either medication long term.

Wegovy v Mounjaro – Which One Should You Choose?

Personal Factors to Consider

When choosing between Mounjaro and Wegovy, it’s tempting to pick the one that promises the most weight loss. However, Some patients find Wegovy works better, with fewer side effects and a gentler effect that lets them enjoy food.

For some patients, cost will be a strong factor. Wegovy’s starting dose usually costs less, but long-term prices can vary between the two treatments.

If you’re not sure which medication to choose, you could try one for a few dose increases. After that, complete the recommended washout period (see below) before starting the other.

This will give you a much better idea of how well your body tolerates each medication. You will see most of the effect from these medications when you reach your maximum dose, which is also your personal maintenance dose. This means you may not see strong effects until you settle on one medication.

Switching Between Treatments

Switching between Wegovy and Mounjaro can be done, regardless of where in your dosing schedule you are. The current guidance is that you should have a “washout period” of at least a week between doses.

So, for example, if you are using 15mg of Mounjaro, you should wait at least a week before starting Wegovy. If you normally take your medication on a Monday, this means you can start your other treatment that following Monday.

Current Mounjaro Dose	Simple’s recommended Wegovy dose if switching
2.5mg	0.25mg
5mg	0.5mg
7.5mg	1mg
10mg	1mg
12.5mg	1.7mg
15mg	1.7mg

If you experience side effects when switching to a  higher dose, please consider restarting Wegovy at the lowest dose and titrating up. This will allow your body to acclimate to the new medication, making it less likely you will experience future side effects.

Key Takeaways

• Mounjaro and Wegovy are weight loss treatments, which work in similar ways. Mounjaro, however, works on more receptors, meaning it can have a stronger effect.
• While they have many similarities, some patients say that one works better for them or has fewer side effects.
• These medications are available with private prescriptions and through the NHS. However, to access them on the NHS, you need to use a Tier 3 Weight Management service. To qualify, you need a higher BMI. You must also have medical conditions such as high blood pressure or type 2 diabetes.
• If you are using one of these medications, you can switch to the other. First, you must go through a “washout” period. This period should last one week for each dose level you were taking. After that, start with the lowest dose of your new medication.

References

Novo Nordisk. (2025). News Details. [online] Available at: https://www.novonordisk.com/content/nncorp/global/en/news-and-media/news-and-ir-materials/news-details.html?id=915087 [Accessed 18 Aug. 2025]

Package leaflet: Information for the patient Mounjaro (n.d.). Available at: https://www.medicines.org.uk/emc/files/pil.15481.pdf

Package leaflet: Information for the patient wegovy FlexTouch. (n.d.). Available at: https://www.medicines.org.uk/emc/files/pil.13800.pdf

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