What is Mounjaro? A Complete Guide | Rightangled

Written by: Rightangled Medical Team
Medically reviewed by: Rightangled Clinical Team
Reading time: 7 minutes

What is Mounjaro?

Mounjaro is a relatively new medication that has become increasingly prominent in medical weight management. It combines two distinct mechanisms of action which, together, offer a more effective approach to weight loss than many previously available treatments. In this article, we explain exactly what Mounjaro is, what it was developed for, who it's suitable for, and how Rightangled - a trusted UK online pharmacy and weight loss provider - can support you if you're considering whether this treatment is right for you.

What is the Active Ingredient in Mounjaro?

The active ingredient in Mounjaro is tirzepatide. It is what's known as a dual agonist: it simultaneously activates two hormone receptors in the body - the GLP-1 receptor and the GIP receptor.

GLP-1 is a hormone that stimulates insulin production, suppresses glucagon release, and slows gastric emptying, helping you feel full for longer. GIP has an additional effect on glucose metabolism and how the body stores and processes fat. Because tirzepatide activates both receptors at once, its effect on satiety and weight loss is generally greater than medications that act on GLP-1 alone.

What is Mounjaro Used For?

Mounjaro was originally developed to treat type 2 diabetes. It helps regulate blood sugar levels by increasing insulin production and suppressing glucagon release, depending on current blood sugar levels - a mechanism that has been demonstrated to be both safe and effective.

Because participants in clinical trials also experienced significant weight loss, tirzepatide was subsequently studied as a treatment for obesity in people without diabetes. It is now approved by the MHRA in the UK (as well as the EMA across Europe) for weight management in adults with a BMI of 30 or higher, or a BMI of 27 or higher when combined with a weight-related health condition.

How Does Mounjaro Help With Weight Loss?

Mounjaro supports weight loss by acting on multiple mechanisms simultaneously. It slows gastric emptying, helping you feel fuller for longer after meals. It also acts on areas of the brain that regulate appetite, reducing the urge to eat. At the same time, its action on GIP receptors influences how the body stores and burns fat. The combined effect of GLP-1 and GIP activity explains why tirzepatide tends to produce stronger weight loss results than earlier single-mechanism medications.

The SURMOUNT-1 phase 3 trial found that participants taking Mounjaro lost an average of 15–22% of their body weight after 72 weeks, with roughly half of those on the highest dose losing more than 20%. [1]

Is Mounjaro Available in the UK?

Yes - Mounjaro is available in the UK through registered, regulated providers such as Rightangled. It has been approved by the MHRA and can be prescribed by clinicians for weight management in eligible adults. As with many GLP-1 and dual-agonist medications, supply can fluctuate, and availability may vary between providers and over time.

If you're considering Mounjaro, the safest and most reliable route is through a registered UK online pharmacy that carries out a proper medical assessment before prescribing - rather than sourcing medication from unregulated sources. You can check your eligibility and access genuine, regulated Mounjaro through Rightangled's Mounjaro page.

What is the Difference Compared to Other Weight Loss Medication?

The key difference between Mounjaro and other weight loss medications lies in their mechanism of action. Medicines such as semaglutide - the active ingredient in Wegovy - are single GLP-1 agonists. Tirzepatide adds GIP receptor activation on top of this dual action.

Across several clinical studies, tirzepatide has demonstrated greater average weight loss compared with semaglutide. A systematic review of available clinical evidence similarly found that tirzepatide is consistently more effective than most other currently available options. [2, 4]

If you'd like a closer look at how the two compare directly - including side effects and dosing - you may find it helpful to read more about Wegovy on Rightangled or explore the weight management programme for a full overview of your options. For US-based readers, Medetone's online weight loss programme also offers further guidance on choosing between GLP-1 treatments.

Who is Mounjaro Suitable For?

Mounjaro is generally intended for adults aged between 18 and 75 with a BMI of 30 or higher, or a BMI of 27 or higher combined with a weight-related health condition such as high blood pressure, sleep apnoea, or prediabetes.

It is not suitable for people with a personal history of pancreatitis, medullary thyroid carcinoma, or MEN2 syndrome, nor for those who are pregnant or breastfeeding. Whether you're eligible for Mounjaro or any GLP-1/dual-agonist medication depends on a range of individual factors that a clinician will assess with you during your consultation.

Is Mounjaro Safe to Use?

Mounjaro has been approved by the MHRA in the UK and the EMA in Europe following extensive clinical evaluation, and is considered safe when used within its approved indications and under proper medical supervision.

The most common side effects are gastrointestinal - nausea, diarrhoea, vomiting, and reduced appetite - particularly in the early stages of treatment or following a dose increase. These typically ease as the body adjusts. Serious side effects such as acute pancreatitis or gallstones are rare but require prompt medical attention. Mounjaro should always be used under clinical supervision, with any side effects reported to your treating clinician.

What Does Rightangled Offer With Mounjaro?

Rightangled offers medically supervised weight loss treatment as a trusted online pharmacy, with Mounjaro available as part of a personalised treatment plan. This means a qualified clinician assesses your individual situation, confirms whether Mounjaro is appropriate for you, establishes the correct dosing schedule, and supports you with regular check-ins throughout your treatment.

How much weight you lose with Mounjaro depends on a number of personal factors, but with proper clinical oversight through Rightangled, you can work towards sustainable, long-term results with confidence. You can find out more about all our weight loss treatment options on our weight management page.

Want to Know More About Mounjaro? Start With a Consultation

Mounjaro is an effective, scientifically validated treatment for people seeking medical support with weight loss. Whether it's the right choice for you depends on your medical history, current weight, and treatment goals. Rightangled can help you answer these questions through a proper medical consultation, so you can make a fully informed decision about your weight loss journey.

Check your eligibility for Mounjaro or explore Wegovy as an alternative GLP-1 option today.

References

1. Jastreboff AM, et al. (2022). Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine, 387, 205–216. https://doi.org/10.1056/NEJMoa2206038

2. Franco JV, et al. (2025). Tirzepatide for adults living with obesity. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD016018

3. Nauck M, et al. (2026). Clinical Potential of GIP in Type 2 Diabetes and Obesity. Diabetes Care. https://doi.org/10.2337/dci25-0141

4. Harbi MH, et al. (2026). Tirzepatide vs. semaglutide for obesity, glycemic control, and cardiovascular outcomes. Frontiers in Medicine. https://doi.org/10.3389/fmed.2026.1764664

5. Medicines and Healthcare products Regulatory Agency / European Medicines Agency. (2023). Mounjaro: Product information. https://www.ema.europa.eu/en/documents/product-information/mounjaro-epar-product-information_en.pdf

This article is for informational purposes only and should not be regarded as medical advice, diagnosis, or treatment. Always speak to a qualified healthcare professional before starting any new medication.