News story

Fake Mounjaro (tirzepatide) KwikPen 15mg pre-filled pens

Fake medicines are illegally produced products that may contain incorrect ingredients, no active ingredients, or harmful substances.

From: Medicines and Healthcare products Regulatory Agency Published 24 February 2026

As a precautionary measure, the Medicines and Healthcare products Regulatory Agency (MHRA) is contacting certain individual patients to make them aware of a small possibility that they may have been dispensed a fake Mounjaro (tirzepatide) KwikPen 15mg solution for injection for weight-loss management from The Private Pharmacy Clinic in Birmingham.

All the affected fake pens identified to date are 15mg pens with the batch number: D873576 dispensed by this pharmacy.

This is a legitimate batch number for genuine Mounjaro KwikPen 7.5mg, and pens at this strength are not impacted.

Dr Alison Cave, Chief Safety Officer at the MHRA said:

“Check the batch number and strength of your KwikPen. If you have one of the affected pens, stop using it straight away. Please report it to the MHRA by emailing info@mhra.gov.uk. Please include “Mounjaro Pens” in the subject line. Keep the pen in a safe place.

“If you have administered injections using the pen already, please be reassured that, based on the cases reviewed to date, the risk to you is low. Testing has confirmed that the identified fake pens do contain tirzepatide, the active substance in Mounjaro, but because the manufacturing conditions are unknown, we cannot confirm that the contents are sterile.

“If you are unsure of how to identify the pen, or are unsure on whether you have administered an affected product and have any questions, please speak to a healthcare professional.

“If you suspect that you’ve had a side effect as a result of using these affected pens, or suspect it’s not a genuine product, or have a defective pen, you can report it to our MHRA Yellow Card scheme. It is important you do not try to extract any of this medicine if a pen is defective in any way.

“If you have a 15mg pen and the batch number is different to D873576, please continue to take the medication as directed by your prescriber.”

As this is an injectable product, if its contents are not sterile, there is potential for infection. Possible signs of infection include:

• Redness, swelling or warmth around the site of the injection
• Pain or discomfort around the site of injection
• Fluid leakage from the site of injection
• Mild fever, chills, fatigue, and sore throat There may also be a risk of allergic reactions to the contents of the pen. Symptoms may include a rash, itching or difficulty breathing.

If patients experience any symptoms of an infection or allergic reaction, they should seek urgent medical attention.

The MHRA has not received any reports of patients requiring treatment after taking these fake medicines. The issue was identified due to faults with the pens, where in all but one case the dose knob came off while in use.

The MHRA was notified of these counterfeits by the manufacturer of the genuine product, Eli Lilly and Company Limited, which has received five reports of faulty pens.

The General Pharmaceutical Council have served a ‘ notice of conditions ’ on the pharmacy involved. The MHRA is continuing with their ongoing investigations

A Drug Safety Update (DSU) for healthcare professionals has also been published, which includes detailed advice on identifying the affected product and managing patients who may have received it.

Notes to editors:

• Fake medicines are illegally produced products that may contain incorrect ingredients, no active ingredients, or harmful substances. Although it may appear similar to the real medicine, a fake medicine has not been manufactured to the correct standards. As a result, we cannot guarantee that the medicine is safe, works properly, or is of the right quality.
• Anyone who suspects they have received a counterfeit medicine or has noticed any fault with a weight-loss pen should report it directly to the Yellow Card scheme, either through the website (https://yellowcard.mhra.gov.uk/) or by searching the Google Play or Apple App stores for MHRA Yellow Card.
• Patients should be reminded on the MHRA guidance on safe use of GLP-1 medicines: GLP-1 medicines for weight loss and diabetes: what you need to know - GOV.UK
• The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for regulating all medicines and medical devices in the UK by ensuring they work and are acceptably safe. All our work is underpinned by robust and fact-based judgements to ensure that the benefits justify any risks.
• The MHRA is an executive agency of the Department of Health and Social Care.
• For media enquiries, please contact the newscentre@mhra.gov.uk, or call on 020 3080 7651.

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Updates to this page

Published 24 February 2026