Yucatan Hospitals Pull Counterfeit Cancer Drug Keytruda After Patient Harm

Mérida, Yucatán — Hospitals in Yucatán have suspended use of the cancer immunotherapy drug Keytruda after counterfeit batches caused adverse effects in patients, officials announced. The Mexican Social Security Institute (IMSS) confirmed the drug is no longer in use at its facilities in the state following a national and international investigation that revealed fake versions circulating in public health institutions.

The Federal Commission for Protection against Health Risks (Cofepris) issued a health alert in March 2026 warning about counterfeit Keytruda® 100 mg/4 mL injectable solution. Previously identified batches Y011745 and Y005786 have been joined by new suspect lots including Y005560, with an expiration date of October 2025, and DR82765, expiring in May 2026. Cofepris emphasized that as counterfeit products, their origin, manufacturing conditions, storage, and transportation are unknown, posing serious health risks with no guarantee of safety, efficacy, or quality.

The alert gained urgency in Yucatán after a patient at Mérida’s Elvia Carrillo Puerto Regional Hospital reported adverse effects following doses from batches later identified as irregular. This incident raised concerns about supply chain controls and oversight mechanisms for acquiring specialized medical supplies within the public health system.

According to the International Consortium of Investigative Journalists (ICIJ), Mexico is the only country among those analyzed where multiple cases of Keytruda counterfeiting have been detected within the public health system. Official records indicate at least 10 institutions acquired vials from batches later flagged by Cofepris. High demand for Keytruda, which costs approximately 97,000 pesos per vial in Mexico, has created pressure on health systems and spawned illegal markets where counterfeit versions circulate.

The Federal Prosecutor’s Office has documented at least 30 incidents related to the drug over the past five years since counterfeiting was first detected, though no convictions have been secured. At least one death has been confirmed associated with use of a counterfeit product.

The withdrawal of Keytruda from IMSS hospitals in Yucatán occurs amid growing concern about the safety and efficacy of medications used to treat serious illnesses. While IMSS authorities assure the drug is no longer in use, the incident highlights failures in quality controls and oversight of specialized medication procurement in the public health system.

As of publication, pharmaceutical manufacturer Merck, which produces Keytruda, had not provided official comment on the matter.