This blog has been co-authored by Jonathon Enston, Henry Williams and Georgia Hughes.

It has been announced that the weight loss jab, Mounjaro (tirzepatide), is set to rise in price by around 170% after the United Stated based company equalised its costs across global markets.

In September of this year, the price per unit for private prescriptions is expected to rise to between £122 and £330 depending on the medication dosage. On top of this, private pharmacies are likely to mark up these unit prices significantly to allow for profit which does not include the addition of VAT. As such, privately funded users can expect to pay over £500 per pen, per month, for the higher doses of the medication.

More positively, the manufacturer of Mounjaro, Eli Lily, has vowed not to raise the unit prices that the NHS currently pays and is working closely with NHS providers to allow access to the medication. The company has said that when it launched in the UK, it agreed to a unit price “significantly” below other European markets to prevent delays in its roll out through the NHS due to high demand.

It is estimated that at least half a million people take weight loss jabs including Ozempic, Saxenda, Wegovey and Mounjaro via private prescriptions in the UK. This price increase is likely to cause many Mounjaro users to switch to another brand of GLP-1 such as its cheaper alternative, Wegovey, although Mounjaro is said to be the more effective option when considering average percentage of weight loss per person.

Whilst some users may switch to another manufacturer, it cannot be left unsaid that this cost increase will likely see the rise in black market medication sales. Many individuals are already accessing the medication through unregulated markets such as social media accounts and unlicensed clinics as a way of bypassing the strict criteria for those who are eligible for weight loss medication or to access cheaper prices. Cybersecurity brand, Avast, uncovered over 5,000 black-market pharmacy websites that are being run by criminal networks where fake versions of GLP-1’s are being sold for as little as £13.70 per dose.

In other news, a new GLP-1 weight loss drug, Retatrutide, is currently at the clinical trial stage and pending the trial results, is set to be available for purchase early 2026. This new weight loss medication is rumoured to be more effective than Mounjaro with claims that users can expect to lose up to 24% of their body weight whereas the rate with Mounjaro is only 22%.