Mounjaro users will soon be getting less of the drug for their money, manufacturer Eli Lilly confirmed today.

The pre-filled injection pens are currently 3ml in size and designed to deliver a fixed amount of the drug once a week, typically over four weeks. 

But this leaves a small amount of medication remaining in the pen after the final injection.

In a cost-cutting tactic referred to as the ‘golden dose’, some individuals withdraw this extra liquid using a syringe and needle to obtain an extra jab. 

Reducing the pen’s size, however, will hinder users from retrieving any additional medication, diminishing their opportunity to extract a fifth dose from the pen. 

Mounjaro patients today took to social media reacting in fury at Eli Lilly’s decision, claiming they would still try the hack. 

Nonetheless, health authorities have consistently cautioned patients against attempting the ‘golden dose’, highlighting that they risk injuring themselves when extracting the fifth dose from the pen and may also expose themselves to infection.

This development follows Eli Lilly’s announcement last month that the wholesale prices of Mounjaro would more than double starting September 1, with the highest dose rising from £122 to £330 monthly, marking a 170 percent increase. 

There is a hidden extra dose in your weight loss jabs that could save you hundreds of pounds, users say — but doctors have warned of major risks

The above image shows there is still liquid left over in the pen after the prescribed four doses — which many say is enough for a fifth

Mid-range doses, such as the 5mg pen, were also set to jump from about £92 to £180. 

Despite the announcement, it triggered ‘Covid-like panic buying’, with users claiming online to have purchased several months’ supply of injection pens to avoid paying the increased price.

Slimmers also took to social media to share tips on how to ‘golden dose’, in an attempt to make the pens last longer on their new price. 

An Eli Lilly spokesperson told the Daily Mail today: ‘A modified KwikPen will be made available globally. 

‘While the modified KwikPen has been approved in the UK, the timelines for availability are yet to be determined. 

‘The original Mounjaro KwikPen and the modified Mounjaro KwikPen both contain the necessary volume of solution for priming before each injection and the delivery of four doses (one dose administered weekly). 

‘The KwikPen has been modified to reduce the amount of leftover medicine that remains in the KwikPen after four doses have been administered.’ 

Each Mounjaro pen contains 3ml of liquid, and each dose uses 0.6ml—just enough for four, accurate, pre–measured doses of Mounjaro. 

Mounjaro patients today took to social media reacting in fury at Eli Lilly’s decision, claiming they would still try the ‘golden dose’ hack

By getting five doses out of each pen, regular users could save around £615 a year.

Currently Pharmacy2U, the UK’s largest online pharmacy, has the strongest Mounjaro pen—15mg—listed at £314, a huge leap from its previous price of £180. 

Furious users today labelled Eli Lilly’s decision a ‘kick in the teeth’ and claimed they would still try to ‘golden dose’.

In one Reddit forum, a user wrote: ‘Wow. This company are truly the gift that keeps on giving.’  

Another said: ‘I think they’ll phase the release so it will be a random chance whether you get the old pen or the new one which will Indirectly make stock piling risky.’ 

Meanwhile a third user said: ‘They really have shafted us all and were likely making a very good profit before the changes.’

Others claimed it wouldn’t stop them from trying to extract whatever was left over. 

‘Maybe half a dose left over so combining two pens with leftover for a full dose. The new golden 9th,’ one said. 

Similar to microdosing, which sees users try and inject a smaller than normal Mounjaro dose, health chiefs have also repeatedly urged patients against trying the ‘golden dose’ hack. 

Dr Alison Cave, chief safety officer of the MHRA, said: ‘People should follow the dosing directions provided by their healthcare provider when prescribed weight–loss medicines and use as directed in the patient information leaflet.

‘Medicines are approved according to strict dosage guidelines. 

‘Failure to adhere with these guidelines, such as tampering with pre–dosed injection pens, could harm your health or cause personal injury.’

Professor Penny Ward, a pharmaceutical expert at King’s College London, also told the Daily Mail: ‘People are reading these tips on online forums and being tempted to use them to save money. 

‘But they’re risking serious side effects from overdosing by doing this — as well as the potential to develop a life-threatening infection. It’s not a good idea at all.

‘These injections contain a slight overfill to ensure the full recommended dose is delivered each time.

‘But by drawing this out with a separate syringe and using it as a so-called fifth dose, you’re exposing yourself to serious risk of infection.

‘The pens are sterile when dispensed, but once they’ve been used, they’re no longer sterile.

‘That means using leftover liquid to inject into the skin could introduce harmful bacteria.

‘This can lead to an abscess—a painful build-up of pus—and if left untreated, potentially progress to sepsis, a life-threatening condition where the body’s organs begin to shut down.’

Under official guidelines, only patients who have a body mass index (BMI) of over 40 and weight-related health problems like high blood pressure, type 2 diabetes and obstructive sleep apnoea, should be prescribed Mounjaro on the NHS. 

But tens of thousands are believed to be using them privately. 

It comes as a damning analysis last week revealed thousands of people are missing out on Mounjaro on the NHS because of a ‘postcode lottery’ of NHS provision. 

Last year, health chiefs announced millions of obese patients would receive Mounjaro—which helps slimmers shed up to a fifth of their bodyweight—on the health service over a phased 12 year rollout. 

But since the rollout began in June, less than half of the commissioning bodies in England have even started prescribing the drug, analysis by the British Medical Journal found.

Weight-related illness costs the economy £74billion a year, with people who are overweight at increased risk of heart disease, cancer and type 2 diabetes.

Two in three Britons are classed as overweight or obese and NHS figures show people now weigh about a stone more than 30 years ago.