What is Mounjaro? Everything to know about NHS approved weight loss jab
Weight-loss injections have surged in popularity, fueled by celebrity endorsements, but are they reaching the people who need them?
One jab that's been capturing public attention and headlines lately is Mounjaro. The Labour Party unveiled plans to introduce the weight-loss jab Mounjaro on the NHS in England in December, aiming to tackle rising obesity levels and support unemployed individuals in returning to work.
Tirzepatide, widely known by its brand name Mounjaro, has received approval from NICE (National Institute for Health and Care Excellence) for treating obesity in England and Wales.
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The decision by NICE also extends to Wales and Northern Ireland, although it remains unclear whether certain groups will be given priority access. Scotland has already approved tirzepatide for obesity treatment through the Scottish Medicines Consortium, leading the way in making this medication available to patients.
Initially, the ambitious rollout suggested that up to 3.4 million eligible patients could benefit from the drug. However, NICE has since called for a phased approach to avoid overburdening the NHS.
However, the health service cannot provide the medication to all eligible individuals right away, as doing so would "simply bankrupt the NHS," according to a BBC report.
As a result, only 220,000 people, roughly 10 percent of those eligible, will receive access to the medication in the initial phase.
Mounjaro, or tirzepatide, has been making waves as a game-changing treatment.
While originally developed for managing type 2 diabetes, the drug has been licensed in the UK to treat obesity since November 2024, gaining popularity for its effectiveness in helping patients achieve significant weight loss.
What is Mounjaro used for?
Mounjaro is a prescription injectable medication designed to help adults with type 2 diabetes better manage their blood sugar levels.
When combined with a healthy diet and regular exercise, it can significantly improve glucose control, supporting a more balanced approach to diabetes management.
According to pharmaceutical company Lilly, which manufactures the medication, Mounjaro works in multiple ways.
It helps:
The body release insulin when blood sugar is high.
The body remove excess sugar from the blood.
Stop the liver from making and releasing too much sugar.
Reduce how much food is eaten.
Slow down how quickly food leaves the stomach. This lessens over time.
How does Mounjaro work?
Mounjaro works by targeting two key receptors, GLP-1 and GIP, to boost the levels of incretins, hormones that play a crucial role in regulating blood sugar.
The drug helps the body produce more insulin when it’s needed while simultaneously reducing the liver’s production of glucose.
Additionally, it slows down the digestion process, which helps stabilize blood sugar levels and lower HbA1c.
By addressing these multiple pathways, Mounjaro not only helps control blood sugar but also supports weight loss, making it a powerful tool in managing obesity and type 2 diabetes.
Who is eligible for a jab of Mounjaro?
Mounjaro is now approved for weight loss and weight management in adults aged 18 and over who meet specific eligibility criteria. The medication works by regulating appetite, helping individuals feel full faster, experience fewer food cravings, and eat less overall.
For best results, Mounjaro is recommended alongside a reduced-calorie diet and increased physical activity.
Currently, Mounjaro is available for weight loss treatment on the NHS in Scotland, where the Scottish Medicines Consortium (SMC) has approved it for individuals with a BMI of at least 30kg/m² and one obesity-related medical condition.
In December 2024, NICE also approved Mounjaro for use on the NHS in England and Wales for individuals with a BMI of 35kg/m² or higher, particularly those with obesity-related conditions like type 2 diabetes or those at high risk of developing it.
How is Mounjaro taken?
Mounjaro is administered as a pre-filled injection pen designed for easy self-injection. It can be injected under the skin of the stomach, thigh, or upper arm.
The starting dose is 2.5mg once weekly for the first four weeks.
The dose is then increased to 5mg weekly.
According to the Medicines and Healthcare products Regulatory Agency (MHRA), doses may be further increased in four-week intervals, up to a maximum of 15mg per week, based on individual needs.
Women using oral contraceptives are to consider additional protection, such as condoms, or switch to a non-oral contraceptive for four weeks after starting Mounjaro. This is due to potential interactions that may reduce the effectiveness of oral contraceptives.
With its targeted approach and flexibility in dosing, Mounjaro offers an effective solution for those looking to achieve sustainable weight management.
Side effects of Mounjaro
Like any medication, Mounjaro can cause side effects, but that doesn’t mean everyone will experience them. When a side effect is listed as "common" in the Patient Information Leaflet, it simply reflects how likely it is to occur.
For example, a "very common" side effect may affect more than one in ten people, while a "very rare" side effect impacts fewer than one in 10,000.
Because medications affect individuals differently, your healthcare team will work with you to decide if Mounjaro is the right choice and discuss any potential side effects.
According to Mounjaro's own website, some of the more frequently reported side effects include:
Nausea
Indigestion
Constipation
Diarrhoea
Low Blood Sugar (Hypoglycaemia)
Mounjaro alone usually doesn’t cause dangerously low blood sugar. However, if taken alongside other diabetes medications like insulin or sulphonylureas, there’s a greater chance of experiencing "hypos".
To reduce this risk, your healthcare team might adjust the dose of your insulin or sulphonylurea when you start Mounjaro.
High Blood Sugar (Hyperglycaemia)
On the other hand, if your insulin dose is reduced too quickly while taking Mounjaro, it can lead to high blood sugar (hyperglycaemia) or even diabetic ketoacidosis (DKA), a serious condition.
Your healthcare team will explain the warning signs of DKA and how to manage them.
A full list of potential side effects can be found in the Patient Information Leaflet included in your medication box. It’s essential to consult your healthcare team before starting Mounjaro and report any side effects you experience.
You can also report side effects directly to the UK’s Yellow Card Scheme, the government system for tracking medication safety.
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