Mounjaro price hike warning as fake weight-loss pens spike

Amid a surge in Mounjaro demand, weight loss injection experts are warning against the dangers of buying from illegal sellers and offering advice on how to identify counterfeit injection pens. 

While many are switching from Mounjaro to the cheaper weight-loss jab WeGovy, there's also been an increase in unscrupulous sellers passing off fake pens as patients desperately seek to stock up ahead of the price changes on September 1.

Really gutted about this. With the price increase of mounjaro, I'll have to come off 😭 Unfortunately £200+ for the medication is too much. I'll have to do this on my own... pic.twitter.com/IVJfjiu5wF

— 𝕊𝕠𝕡𝕙𝕤 𝕨𝕖𝕚𝕘𝕙𝕥𝕝𝕠𝕤𝕤 𝕛𝕠𝕦𝕣𝕟𝕖𝕪🏃🏽 (@onlysophsworld) August 17, 2025

“With the recent price hikes, we’re likely to see more and more people turning to unregulated sellers because the medication may be cheaper," says Jason Murphy, Head of Pharmacy at Chemist4U.

"This is extremely unsafe as many of these sources distribute counterfeit versions of Mounjaro, which pose serious risks to your health. Beyond the lack of quality control, patients may be exposed to harmful ingredients or medications that don’t contain the active drug at all, so what might seem like a cost-saving shortcut could end up causing severe harm."

There's a warning that as well as putting their health at risk, patients buying fake pens may risk falling foul of drug laws.

“Purchasing in large amounts from unregulated sources may also violate drug laws, potentially leading to fines or criminal charges, which is why it’s important that patients only access Mounjaro through legitimate, regulated channels," says Jason.

“If you think you can no longer afford Mounjaro following the price increase, speak with your healthcare provider. Many patients are switching to Wegovy, a GLP-1 medication that works in a very similar way to Mounjaro that has not been affected by the price hike.” 

How can you spot a fake Mounjaro pen? 

Chemist4U says there are three main identifiers that suggest a pen is counterfeit.

1. The first key identifier is cost: if the cost of the medication seems too good to be true, it most likely is. Weight loss pens aren’t cheap, which is why many seek cheaper alternatives.  
2. The next identifier is the source. Wegovy and Mounjaro are prescription-only medicines, and they can only be issued by specialised medical professionals after a consultation. You should be asked about your medical history and weight and asked to provide photographs to confirm that the information given is accurate. This is all to ensure the medication is safe and the right choice for you.  
3. Steer clear of any weight loss injections advertised on social media, in salons and even online by some unlicensed pharmacies. For peace of mind, check that the pharmacy is regulated by the General Pharmaceutical Council (GPhC) and the Medicines and Healthcare products Regulatory Agency (MHRA) before you commit. 
4. Finally, the appearance. When comparing fake weight loss pens to real ones, there are several differences in their appearance to look out for. While real weight loss pens come in well-designed packaging with clear, high-quality printing and branding, packaging for fake pens may have spelling mistakes, blurry printing or incorrect logos.  
5. The materials used for real pens feel solid and well made, whereas a fake pen is likely to feel cheap, flimsy and have more obvious flaws like uneven colouring, rough edges or loose parts.  
6. While real pens will likely have a unique serial number, fake products either won't have one that matches the manufacturer's records or won't have one at all. A real pen should contain liquid that is clear and colourless. Unknown substances in fraudulent pens can be cloudy or tinged with colour, a dead giveaway that they are fake. 

🗣️"We’d urge patients to avoid bulk ordering Mounjaro as well as buying the medication at massively reduced prices."

NPA Chief Exec @HenryMGregg and @SukhiBasra1 spoke to @guardian about the impact of recent increases in the cost of Mounjarohttps://t.co/OCX0BVcjjH

— National Pharmacy Association (@NPA1921) August 26, 2025

Can you stock up on Mounjaro ahead of the September 1 price hike?

“Buying Mounjaro in bulk is not possible with UK registered pharmacies or clinics, so if you are bulk buying, it is likely from unregulated sources, which can be extremely dangerous," says Jason.

"Medications purchased by unregulated sellers may be counterfeit or contain harmful substances, and without professional guidance, patients risk taking the wrong dose or missing critical monitoring for side effects. Taking too much or too little can reduce effectiveness, cause side effects or trigger serious health problems like hypoglycemia or pancreatitis." 

Recommended reading: 

• What is the Mounjaro 'golden dose' to stop food noise
• When will Mounjaro be rolled out on the NHS?
• Warning as Mounjaro and Ozempic sold without prescription 

Mounjaro requires proper storage and buying in bulk increases the chance it will be stored improperly, reducing effectiveness or making it unsafe.

"You should store an unused KwikPen in the refrigerator between 2 to 8 degrees," he adds.

"Make sure you protect the medicine from light so keeping in its packaging, and if you place it at the back of your fridge, ensure it doesn’t freeze, and if it does, discard the pen.  

"Once opened, the pen can be stored at room temperature (up to 30°C) and should be discarded after four weekly doses, or if more than 30 days have passed since first use. The shelf life of Mounjaro is 24 months but it’s important to always check the expiry date on the pen’s packaging. The expiry date is stated on the pen label and on the carton after EXP. The date reads as the month and year and refers to the last day of that month.”