Fake Mounjaro pens — February 2026 MHRA alert

What the alert said

The MHRA’s February 2026 alert highlighted the Mounjaro 15 mg KwikPen specifically — the highest tirzepatide strength, the most expensive, and therefore the most attractive to falsifiers. Falsified pens were reported reaching UK patients who had obtained supplies outside the regulated UK pharmacy chain. Patients reported unexpected adverse reactions and inconsistent or absent therapeutic effects — consistent with the contents not being genuine tirzepatide at the stated concentration.

Refer to the live MHRA Drug Safety Update for the current text of the alert and any subsequent updates.

How to identify a genuine Mounjaro KwikPen

• Outer carton: Eli Lilly branding, UK Patient Information Leaflet in English, the matching dose strength printed clearly, tamper-evident seal intact, matching batch number and expiry date on the box and the pen.
• Pen body: Recognisable Lilly KwikPen design, dose dial mechanism, clear printing on the label, ink that doesn’t smudge.
• Cartridge solution: Clear, colourless, no particulates.
• PIL: A folded UK PIL in English should be in the box. PIL absent or in another language only is a red flag.

Red flags — likely counterfeit

• Supply arrived in a vial rather than a pen.
• No PIL in the box.
• PIL in a non-English language only.
• Poorly printed packaging, smudged ink, spelling errors.
• Mismatched batch number or expiry between box and pen.
• Tamper seal broken on arrival.
• Pen feels different in weight, dial mechanism is different.
• Cartridge contents discoloured or contain particulates.
• Bought outside the regulated UK pharmacy chain (peer-to-peer, gym contact, non-UK pharmacy, online reseller).
• No genuine UK prescription behind the purchase.

What to do if you suspect a fake

1. Don’t inject. Don’t take the next scheduled dose.
2. Photograph everything. Carton (all sides), pen body, PIL (if any), the cartridge if visible. Don’t damage or discard.
3. Contact your dispensing pharmacy. If you obtained the product via a UK pharmacy and they dispensed it, they need to know. If the product came from outside the UK pharmacy chain, skip this step.
4. Report to MHRA via Yellow Card. Yellow Card covers fake medicines as well as adverse reactions.
5. Report via the GOV.UK form. Report a problem with a medicine or medical device. Include URLs, screenshots, payment evidence, and shipping details if you bought via an unlicensed route.
6. If you have injected: Contact your prescriber or NHS 111. Watch for unusual reactions, infection at injection sites, and unexpected glycaemic changes (especially if diabetic).
7. If you bought via an unlicensed route: Reporting to Action Fraud is also appropriate.