Mounjaro for Weight Loss in the UK

Mounjaro is a once-weekly prescription-only injectable containing the active ingredient tirzepatide. This works by targeting two natural hormone receptors, GLP-1 and GIP which help to regulate blood sugar, slow down digestion and reduce appetite.

Put simply, it helps you feel fuller, quicker, for longer - reducing food intake which can result in weight loss.

Mounjaro was originally approved to treat adults with type 2 diabetes. The MHRA has recently approved its license for weight management in adults with obesity (BMI ≥ 30) or those who are overweight (BMI ≥27) with one weight-related condition. This is in line with the manufacturers guidelines and individual clinical assessment.

In the UK, Mounjaro has gained a lot of attention because of clinical evidence showing it can lead to significant, sustained weight loss. Results from the SURMOUNT-1 trial show it can help people lose up to 21% of their weight, when combined with healthy lifestyle changes.

When used for diabetes, the primary benefit is blood sugar control. For weight management, the focus shifts to appetite suppression and sustained fat loss.

This weight loss effect is why Mounjaro is now being used beyond diabetes care. Excess weight and obesity are major contributors to type 2 diabetes and cardiovascular disease in the UK, making treatments that address both weight and metabolic health clinically significant.

At a glance:

• Once weekly injection
• MHRA approved
• Dual action therapy
• Up to 21% weight loss
• Most effective weight loss treatment currently licensed in the UK

How Mounjaro works for weight loss

The first of its kind as a dual action therapy, Mounjaro (tirzepatide) activates GLP-1 and GIP receptors. In doing so, it can potentially cause greater weight loss compared to other treatments which only target GLP-1.

By activating GLP-1, tirzepatide influences appetite suppression. It does this by increasing the fullness feeling after a meal, slowing the time taken to empty the stomach, and blocking another hormone - glucagon.

Glucagon helps release stored sugars from the liver. By blocking this, blood sugar levels are lowered, making the body steer towards fat for energy, encouraging fat breakdown.

By activating GIP, tirzepatide influences insulin sensitivity, helping to regulate blood sugar levels. This reduces blood sugar ‘dips’ which can lead to food cravings, thus helping with weight loss. Additionally, GIP enhances GLP-1 activity whilst also discouraging fat storage.

What happens in the body:

• You administer the once-weekly dose.
• The medication sends signals to the brain telling it ‘I'm full’ much earlier and for longer.
• The stomach starts to empty more slowly, keeping the fullness feeling for longer.
• Other organs work together to keep blood sugar steady, reducing the triggers for snacking.
• Improved insulin sensitivity allows the body to use stored fat as energy, much more efficiently.-

Is Mounjaro approved for weight loss in the UK?

Mounjaro has been approved for weight loss in the UK since November 2023. The Medicines Healthcare Regulatory Authority (MHRA), regulates tirzepatide to ensure it is safe and effective.

Licensing differs from prescribing. Prescribing is the act of approving a medication for a specific patient. This may or may not be in line with the product's official license.

When a medicine is not prescribed in line with its MHRA license, this is referred to as off-label use. This is a common, legal practice and is based on the prescribers clinical judgement.

The national institute for health and care excellence (NICE), issues obesity guidelines. These guidelines are evidence based and set out best practices for obesity treatments, guiding the prescribing process.

Prescribers within the NHS are tightly bound to prescribe treatments which are cost-effective and included in their local NHS prescribing formularies.

Whilst NHS England commissions weight management services, patient access is limited by long waiting lists and strict eligibility criteria. Often, individuals with a very high BMI and multiple weight-related conditions are prioritised. In some areas, there may not even be a local weight management pathway.

For those looking to ‘fast track’ onto Mounjaro treatment, a private clinic may be the better option. Private clinics offer greater access and flexibility, even if you don’t meet NHS thresholds. Whilst the patients bear the cost of the treatment, fewer waiting list delays and one-to-one support offer advantages to help kick start your journey.

Who can be prescribed Mounjaro for weight loss in the UK

In the UK, Mounjaro can be prescribed for weight loss through the NHS or private clinics, such as Quick Meds.

The eligibility criteria assesses a patient's BMI, (body mass index) which determines obesity classification. BMI is a ratio of weight in relation to height with a BMI of 25 to 29 considered overweight, and a BMI of 30 or over considered obese.

Additional criteria assesses the presence of weight-related health conditions. These are conditions which are worsened, or caused by excess weight. Obesity increases the risk of conditions like type 2 diabetes and cardiovascular disease. Addressing obesity in these patients has the potential to significantly improve a patient's overall health and well being.

A prescriber uses their clinical discretion, taking into account the eligibility criteria and other individual factors to inform their prescribing decision.

There may be times where patients do not qualify for treatment. This could be due to not meeting the BMI criteria, taking an interacting medication or suffering from a conflicting medical condition.

It's important to remember, Mounjaro is not for everyone. As a prescription only medication, prescribers have a duty to ensure the treatment will be safe for you, before authorising a supply.

Eligibility criteria checklist:

• Age - over 18 years
• BMI ≥ 30 (obese)
• BMI ≥ 27 with a weight related health condition

Common exclusion reasons:

• Low BMI
• Under 18 years
• Pregnant or breastfeeding
• Medical history
• History of medullary thyroid carcinoma (MTC)/MEN2
• History of pancreatitis
• Active gallstones
• Severe gastrointestinal disease
• Severe liver or kidney disease
• Type 1 diabetes
• History of eating disorders
• Allergic to tirzepatide or any other ingredients
• Taking medication which interacts with Mounjaro.

Mounjaro vs other weight loss injections

Other medicines licensed for weight loss are Wegovy, which contains semaglutide, and Nevolat which contains liraglutide.

Semaglutide activates the GLP-1 receptor only. Like Mounjaro, this is a once-weekly injectable treatment with a similar side effect profile. Mounjaro has been compared with Wegovy in a head to head trial.

SURMOUNT-5 assessed weight loss in patients taking the highest tolerated doses of Mounjaro and Wegovy. This trial was conducted over 72 weeks and found average weight loss with Mounjaro was 20% compared to 13% with Wegovy. The results show Mounjaro is significantly more effective at helping achieve weight loss.

Liraglutide, like semaglutide, only activates GLP-1 receptors. The difference between Nevolat and other treatments is that it is administered once-daily, not weekly. STEP-8 clinical trials have compared the effectiveness of Wegovy with Nevolat. This trial, carried out over 68 weeks, found an almost 16% weight loss in those taking Wegovy compared to 6% in the Nevolat group. This trial confirms Wegovy is more effective.

Dual agonist therapies like Mounjaro are the most effective treatments on the market. This is as it targets multiple pathways, leading to greater weight reduction compared to treatments that only activate a single pathway.

	Mounjaro	Wegovy	Nevolat
Mechanism	Dual GLP-1/GIP	GLP-1 Only	GLP-1 Only
Dosage schedule	Once weekly	Once weekly	Once daily
Typical weight loss in trials	20% over 72 weeks	13% over 72 weeks	6% over 68 weeks

Expected weight loss results with Mounjaro

Clinical trial data from the SURMOUNT trials provides a closer look at how effective Mounjaro really is. Here’s a breakdown of what the trials actually tell us:

The SURMOUNT-1 trial assessed weight reduction at different doses. The results highlight that over 72 weeks, higher doses of tirzepatide are associated with greater weight reduction. Patients lost on average of:

• 15% with 5mg
• 19.5% with 10mg
• 20.9% with 15mg

Another trial, SURMOUNT-3, looked at the impact of lifestyle changes alongside Mounjaro. Individuals who had already started to make changes before taking Mounjaro, found they lost an average of 24% of their initial weight. This confirms whilst effective, weight loss medication requires lifestyle changes for optimal results.

Whilst a calorie deficit supports fat loss, sustainable lifestyle changes are important. Sustainable changes which can be maintained long term support maintenance of a healthier weight, reducing the risk of future weight gain.

Importantly, everyone's journey is different. With the clinical trials, some participants took longer to respond than others (late responders). Reasons for variability could be due to starting weight, the presence of weight related conditions and how consistently lifestyle changes were adhered to.

Dosage, administration, and treatment duration

Mounjaro is [administered](*https://medical.lilly.com/uk/products/answers/how-to-use-the-mounjaro-tirzepatide-kwikpen-219072_ as a subcutaneous injection, usually into the stomach but also into the thighs or upper arms. The once weekly injection improves adherence to treatment, offering convenience daily injections like Nevolat.

Available in up to [6 dose]9(*https://www.medicines.org.uk/emc/product/15484/usermanual) strengths, patients new to treatment must start at the lowest dose (2.5mg). The dose is increased every 4 weeks as tolerated until a maintenance dose has been reached.

It is recommended to maintain the lowest, most effective dose for as long as possible. Unnecessarily increasing the dose will not achieve faster weight loss and a slower dose escalation can reduce side effects.

One Mounjaro pen is pre-filled with 4 doses lasting 4 weeks. Whilst there is no set limit for how long it can be taken for, it is intended for long-term use.

How long an individual patient will remain on treatment depends on the amount of weight to lose and consistency to both the treatment itself and lifestyle modifications.

How to use the Kwikpen - Wash your hands - Remove the pen cap and inspect the medication - The solution should be colourless/slightly yellow, not frozen or cloudy and with no particles - Attach a new needle and remove the outer and inner needle caps - Conduct a flow test - to remove air bubbles and make sure the pen is working correctly - Choose your injection site - Inject a full dose - Turn the dose knob until a ‘1’ icon appears in the dose window - Insert the needle into the skin - Push the dose knob in until it stops, then hold for an additional 5 seconds - Dispose of the needle safely. - Store the pen appropriately until your next dose.

Practical tips: - Remain consistent in dosing. Skipping doses may affect treatment outcomes - Bring the pen to room temperature before injecting - to reduce pain. - Inject into the stomach rather than arms/thighs. The stomach is easier to reach and contains more fatty tissue, aiding absorption. - Rotate injection sites each week to reduce the risk of injection site reactions

Side effects and safety considerations

Mounjaro is considered a safe treatment when used in line with medical advice. Most side effects are mild and not everyone experiences them.

Tirzepatide may cause gastrointestinal side effects such as nausea, vomiting, diarrhoea and constipation. These are the most common side effects which occur when treatment is first started, or when the dose is increased.

Other serious side effects include an allergic reaction, pancreatitis or gallbladder problems. These are all medical emergencies which require immediate medical attention.

It's important to speak to your provider about your medical history and if you are taking any other medication. A history of thyroid tumours, kidney problems or severe stomach problems must be considered carefully before starting the treatment.

The use of other medication must also be assessed prior to treatment initiation. If you take medicines such as insulin, when combined with Mounjaro, this can lead to hypoglycaemia - low blood sugar.

Whilst on treatment it's important to let someone know if you experience any side effects. Your healthcare professional can monitor adverse effects ensuring optimum treatment outcomes.

Common side effects	Urgent side effects – seek urgent medical attention
Nausea	Anaphylaxis (severe allergic reaction)
Vomiting	Acute pancreatitis
Diarrhoea	Gallstones
Constipation	Sudden vision loss
Abdominal pain

Buying Mounjaro safely in the UK

It's important to source Mounjaro only from regulated suppliers. All online pharmacies must be registered with the General Pharmaceutical Council (GPhC).

As a prescription medication requires clinical assessment, a registered pharmacy should ask about your health, ensuring the medication is safe and appropriate. Ongoing clinical supervision is necessary, ensuring dose titration and any side effects are managed appropriately.

In the UK, medicines and devices are regulated by the MHRA. This ensures they are safe, effective and meet quality standards. The MHRA warns against counterfeit medicines and urges patients to exercise caution when buying online.

Counterfeit medicines may not contain what they say they do. These may be contaminated or contain a different medicine altogether. The usage of counterfeit medicines can significantly impact health.

Before placing your order, following this simple guide to check for safety:

• Is the pharmacy registered with the GPhC
• You can verify GPhC registration here.
• Confirm the website is UK-based
• Regulated online pharmacies should provide a physical UK address and phone number.
• Make sure a prescription is required
• Legitimate pharmacies will ask you questions about your health which is reviewed by a healthcare professional.
• Check the professionals credentials
• Ensure your prescriber is registered with the GPhC for pharmacists or GMC for doctors.
• Avoid warning signs
• Bold claims or prices significantly lower than current market value should raise alarms.

Life after stopping Mounjaro

Appetite regulation may change after medication cessation. Food noise can return to normal and some patients may be at risk of weight regain. The key to ensuring weight stays off is a long-term realistic approach to lifestyle changes.

When starting treatment, we know weight loss and maintenance requires behaviour change. This includes a reduction in calorie intake, and an increase in physical activity.

As tirzepatide reduces hunger cues and appetite, it can be expected for hunger to return to pre-treatment levels when treatment is stopped. To manage this, it’s important to make sustainable lifestyle changes whilst on the treatment, which can then be maintained when you stop.

It's best to think of Mounjaro use as a transitional period towards long-term lifestyle modifications. Making small, manageable changes which you would be happy to commit to, once you come off the medication can help you maintain a healthier weight.

Focus on building up towards your exercise goals, aiming for 150 mins of moderate intensity exercise per week. Additionally, make smaller changes to your current meals, keeping the familiar tastes but reducing their carb content, salt and saturated fats.

Individuals more likely to regain weight are those who have made drastic changes which cannot be maintained in the long run. This results in reverting back to old habits.

Long term weight management benefits from ongoing support. Work alongside your healthcare provider or dietitian for structured advice and follow-up support which is important in helping you keep the weight off.

Post treatment strategies: - Slowly come off treatment, don't stop abruptly - Make gradual, manageable lifestyle changes

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