Counterfeit GLP-1 pens: what the FDA has warned

What “counterfeit” means, and how it differs from compounded

The FDA describes counterfeit, or falsified, medicines as products passed off as the real thing that may contain the wrong ingredients, too much or too little active ingredient, none at all, or other harmful substances. They are illegal ^[2].

This is different from compounding. A compounded drug is made by a pharmacy or outsourcing facility and is not FDA approved, but it does not pretend to be a brand-name product. A counterfeit copies the brand: the pen, the label, the leaflet and the box. The line can blur, because the FDA has also found compounded semaglutide and tirzepatide with false labels naming pharmacies that do not exist or did not make them ^[3]. The article on compounded GLP-1s covers that side.

The notices so far

The table lists the notices this article could verify on regulator or manufacturer pages. Each one turned on details printed on the pen or pack, which is why they are given in full.

What the FDA found in the US cases

In December 2023 the FDA said it had seized thousands of counterfeit units found in the legitimate supply chain and that some might still be on sale. Analysis showed the needles were counterfeit, so their sterility could not be confirmed, which the FDA said raised the risk of infection ^[1]. It knew of five adverse events for that lot at the time, none serious ^[1].

The April 2025 update followed a report from Novo Nordisk on 3 April; the FDA seized the identified products on 9 April and said none of the six adverse event reports for that lot appeared to involve the counterfeit ^[1]. The December 2025 update followed a report on 18 November 2025. Because PAR1229 is also a real lot, the FDA pointed to the label layout instead, and said pens from that lot supplied through the Novo Nordisk Patient Assistance Program are authentic ^[1]. Testing of those seized products was still under way when the notice was posted ^[1].

Beyond the US: Europe, the WHO and the UK

The EMA’s 2023 alert concerned pens that carried batch numbers, barcodes and serial numbers copied from genuine packs. EU packs can be checked in an EU-wide system, and the copied serials showed as inactive ^[7]. The agency found no evidence that the pens reached patients through legal pharmacies, and told patients to compare their pens with the package leaflet and return any that look different to the pharmacy ^[7].

The WHO’s 2024 alert said the falsified Ozempic® had entered regulated supply chains, and warned that using it could mean ineffective treatment from a wrong dose, contamination or unknown ingredients ^[8]. Its question-and-answer page adds that some falsified semaglutide had no active ingredient, and some held another undeclared one such as insulin ^[9].

In February 2026 the UK regulator reported fake Mounjaro® KwikPen® 15 mg pens. Testing found tirzepatide in them, but the agency could not be sure they were sterile, and asked patients not to try to draw a dose from any defective pen ^[6]. It had received no reports of harm needing treatment ^[6]. Lilly says it has also seen products sold as tirzepatide with bacteria, impurities, a pink colour, and in one case nothing but a sugar alcohol ^[10].

Checks that manufacturers and regulators describe

• Compare the pen and pack with your usual ones and with the leaflet; a different look is the first sign the FDA lists ^[2][7].
• Read the lot and expiry on both pen and carton, and compare them with any notice. Check that the lot matches the strength printed on the pen; the MHRA case turned on that ^[6].
• For Ozempic®, Novo Nordisk’s 2023 statement says genuine pens do not get longer as you dial a dose, and the dose window shows only that pen’s intended doses ^[5].
• Novo Nordisk and the WHO describe fakes with poorly attached labels, spelling mistakes on the carton or, according to Novo Nordisk, no tamper-evident perforation ^[5][8].
• The WHO advises checking that the pack is undamaged and shows the manufacturer, batch and expiry, and warns against injectable semaglutide kept outside a refrigerator ^[9].
• Notice a new or unusual side effect after using a new pen; the FDA lists that as a possible sign ^[2].

Where the FDA says to get the medicine

The FDA’s advice is the same across its notices: get the medicine with a valid prescription through a state-licensed pharmacy and check it before use. It tells pharmacies to buy only through the manufacturer’s authorised distributors ^[1].

For online purchases, the FDA’s BeSafeRx pages explain how to look a pharmacy up in your state board of pharmacy’s licence database and say not to use it if it is not listed. A listed pharmacy should also give a physical US address and phone number and have a licensed pharmacist to answer questions ^[4]. The FDA adds that semaglutide and tirzepatide sold illegally online may be counterfeit ^[3]. Outside the US, the WHO advises buying only from authorised or licensed suppliers ^[8].

If you think a pen is fake

• Do not use a product that matches a notice. Keep it with its box and label and contact the pharmacy that supplied it ^[1][7].
• Do not try to draw a dose from a defective pen ^[6].
• In the US, report side effects to the FDA’s MedWatch programme, and report a suspected counterfeit or seller to the FDA’s criminal investigations office ^[1][2]. Lilly also asks people to tell its answer centre and their state board of pharmacy about suspect tirzepatide ^[10].
• Elsewhere, the WHO asks for suspected falsification to be reported to the national medicines regulator; in the UK that is the Yellow Card scheme ^[8][6].
• Ask your pharmacist or prescriber what to do about your next dose.

Ozempic® and Wegovy® are registered trademarks of Novo Nordisk A/S. Mounjaro®, Zepbound® and KwikPen® are registered trademarks of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Novo Nordisk or Eli Lilly and Company.