UK regulators find falsified Mounjaro KwikPen 15 mg pens at one online pharmacy

The UK Medicines and Healthcare products Regulatory Agency (MHRA) said on February 24, 2026 that five falsified Mounjaro (tirzepatide) KwikPen 15 mg pre-filled pens had been supplied through a single online pharmacy, The Private Pharmacy Clinic in Birmingham, England ^[1][2]. The agency said all 15 mg pens carrying batch number D873576 are falsified, and healthcare professionals should not supply them ^[1][2].

The pens were identified because of mechanical faults. In all but one case the dose knob came off while the pen was in use, and every pen found so far has had a faulty mechanism ^[1][2]. The batch number and the 10/26 expiry date on the falsified packs match a genuine Mounjaro KwikPen 7.5 mg pen, so the MHRA said the expiry date is not the relevant check — batch number and dose are ^[1]. Genuine 7.5 mg pens are not affected ^[1][2]. Eli Lilly and Company Limited, which makes Mounjaro, told the MHRA about the five pens ^[1].

Testing of the recovered pens confirmed they do contain tirzepatide ^[1]. But because the MHRA does not know how the pens were manufactured, it said it cannot be sure the contents are sterile. Since the product is injected, a non-sterile contents could cause infection, and allergic reactions may also occur, the agency said ^[1].

The MHRA said it has not received any reports of patient harm that required treatment after someone used this falsified medicine ^[1][2]. For people who already injected from an affected pen, the agency's patient advice says that, based on the cases reviewed so far, the risk is low ^[1][2]. Patients who have a 15 mg pen with the matching batch number should not use it and should not try to extract a dose from a defective pen, according to the MHRA ^[1]. The pharmacy involved is unable to provide more of this medication at this time, and patients may need replacement medication to continue treatment ^[1][2].

The General Pharmaceutical Council served a notice of conditions on the pharmacy involved, and the MHRA said its investigation is continuing ^[1][2].

Why it matters for patients

This case is a reminder that the risk from a falsified injectable is not only about whether the drug inside is real. Regulators confirmed tirzepatide was present in these pens, yet still called them unsafe because the manufacturing route was unknown and sterility could not be verified ^[1]. Infection and hypersensitivity are the concerns the MHRA flagged, and it advised that anyone who believes they used a falsified product should be assessed for signs and symptoms of infection or allergic reaction ^[1].

Practical details matter here. The MHRA said the expiry date is not the useful check — patients and pharmacists should look at the batch number and the dose together ^[1]. The agency also asked patients not to try to extract a dose from a pen that is defective in any way, and to keep a suspected falsified pen in a safe place so the MHRA can arrange collection ^[1].

The affected pens are a UK product supplied by one UK online pharmacy, and it has not been reported that this batch reached the United States or that US regulators have issued any statement about it. It also has not been disclosed how the falsified pens entered the supply chain or where they were made ^[1][2].

What happens next

The MHRA said its investigation into the falsified pens is ongoing, and no completion date has been disclosed ^[1]. The General Pharmaceutical Council's notice of conditions is dated February 19, 2026 ^[1]. Patients in the UK who have a 15 mg Mounjaro KwikPen with batch number D873576 were asked to report it to the MHRA by email with "Mounjaro Pens" in the subject line, and to report side effects or suspected defective pens through the Yellow Card scheme ^[1][2]. The MHRA said it has not received reports of harm requiring treatment from these pens ^[1][2].