Dr Ashwin Sharma

Article by Dr Ashwin Sharma

Your Complete Guide To Mounjaro

Looking for extra support to reach your weight loss goals? Many treatments can help you lose weight safely and sustainably. Mounjaro is a new medication designed to treat obesity or weight-related health problems. It contains tirzepatide, a drug that helps control hunger and improves how your body uses insulin, making it easier for you to lose weight.

At MedExpress, we know every weight loss journey is unique. Starting treatment can feel like a daunting step, and you need to choose the right medication for you. Our experts break down what Mounjaro is, how it works and who can use it to help you make an informed decision about seeking treatment. 

What is Mounjaro?

Mounjaro is an injectable treatment containing the drug tirzepatide. It’s a new medication used to manage type 2 diabetes, but it’s a successful weight loss treatment too. 

You take it once a week with a pre-filled pen, self-injecting into your abdomen, thigh, or upper arm.

How does Mounjaro work?

Mounjaro contains the active ingredient tirzepatide, which activates two different types of receptors in your gut: glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP). These receptors stimulate hormones that help control your blood sugar. Activating them helps to reduce your appetite and make you feel full for longer. 

Because Mounjaro affects two types of receptors, instead of one, it’s more effective for weight loss than other injectable medications. Studies show that, by reducing your food intake and slowing down digestion, Mounjaro can lead to a significant decrease in calorie consumption.

Mounjaro in the UK

In the UK, you can now support your weight loss with Mounjaro KwikPen. It’s approved by MHRA (Medicines and Healthcare products Regulatory Agency) and backed by strong clinical evidence from trials. 

Mounjaro KwikPen is designed to be minimally invasive, with small needles for comfort, and can be self-injected into your abdomen, thigh, or upper arm. MedExpress offers support throughout your treatment, so you can get guidance whenever you need it.  

How effective is Mounjaro?

In clinical trials, people using Mounjaro experienced significant weight loss. On average, those on the highest dose of 15 mg lost an average of 20% of their body weight after 72 weeks [1]. 

Mounjaro vs. other weight loss treatments

Research shows that Mounjaro leads to more significant weight loss than treatments containing semaglutide, like Wegovy and Ozempic. In a recent study, people taking Mounjaro lost up to an extra 6% of their body weight compared to people taking semaglutide [2]. So, if someone taking semaglutide lost 10% of their body weight, someone taking tirzepatide might lose about 16% of their body weight. It also found that a higher percentage of Mounjaro users lost at least 5% of their body weight compared to people using semaglutide. 

Side effects

Like all medications, Mounjaro can cause some side effects. It’s important you’re aware of them before starting treatment. These are the common side effects:

  • Nausea, diarrhoea, or vomiting are common, but will settle with time. 
  • You may also have constipation, indigestion, and abdominal pain. Our clinical team can offer support to help you relieve these symptoms. 
  • Injection site reactions can cause redness and irritation. These are generally mild.

You can manage side effects with dietary changes, like choosing bland foods and staying hydrated. We also recommend that you limit caffeine and alcohol intake, stay active and speak to our clinical team for advice on changing dosage or timing to relieve symptoms. 

Who can use Mounjaro?

It’s important to know if you can safely use Mounjaro and make the lifestyle changes that come with taking it. For the best results, Mounjaro should be paired with a lower-calorie diet and more physical activity.

You’re eligible to take Mounjaro if you have a BMI of 30, and you may be eligible if you have a BMI of 27 and weight-related health conditions. These related concerns include high blood pressure, diabetes, heart disease and raised cholesterol.

If you have Type 2 diabetes and a BMI less than 27, you can use other treatments for weight loss. 

Mounjaro isn’t suitable for you if you have:

  • Severe kidney or liver problems
  • Type 1 diabetes
  • A personal or family history of thyroid cancers or certain genetic conditions
  • An allergy to tirzepatide or any other ingredients

Mounjaro also isn’t suitable if you’re pregnant or breastfeeding. 

If you have a history of pancreatitis, serious digestive issues, diabetic retinopathy or kidney problems, speak to your GP before starting Mounjaro.

Ready to start your weight loss journey? Take a free consultation today and our clinical experts will find the right treatment for you. 


[1] https://www.nejm.org/doi/full/10.1056/NEJMoa2206038 

[2] https://www.nejm.org/doi/full/10.1056/nejmoa2107519

Dr Ashwin Sharma
Dr Ashwin Sharma
Dr Ashwin Sharma is a medical doctor and writer with a particular interest in health technology, artificial intelligence and medical weight loss. He completed his training at the University of Leicester and Imperial College London, and has since been exploring the intersections of medicine, technology, and communication.
Originally published March 21 2024, updated April 16 2024