New Delhi : HL August 07, 2026
A major evaluation by the World Health Organization’s International Agency for Research on Cancer (IARC) has identified three widely used medicines—hydrochlorothiazide, voriconazole, and tacrolimus—as carcinogenic to humans (Group 1), citing sufficient scientific evidence linking them to certain types of cancer. The findings were published in The Lancet Oncology and are detailed in IARC Monographs Volume 137.
Hydrochlorothiazide is a commonly prescribed medication for high blood pressure, voriconazole is used to treat serious fungal infections, and tacrolimus is an immunosuppressant widely administered to organ transplant recipients to prevent organ rejection. According to IARC, long-term exposure to these medicines has been associated with an increased risk of specific cancers, particularly cutaneous squamous cell carcinoma, a form of skin cancer. The evaluation was based on extensive reviews of human, animal, and mechanistic evidence.
Medical experts, however, stress that patients should not discontinue these medicines without consulting their doctors. For many individuals, especially organ transplant recipients, these drugs are life-saving, and abruptly stopping treatment can result in severe complications, including organ rejection, uncontrolled infections, or worsening of underlying diseases.
Doctors explain that the reported cancer risk is primarily associated with long-term, high cumulative exposure, and the absolute risk for many patients remains relatively low. Regular medical follow-up, routine skin examinations, protection from excessive sun exposure, and timely reporting of any suspicious skin changes can significantly reduce the likelihood of serious outcomes.
Physicians also note that alternative medicines may be available for some patients, particularly those taking hydrochlorothiazide for hypertension. However, any decision to switch medications should be made only after a careful assessment of the patient’s overall health, medical history, and treatment needs.
The IARC classification identifies a cancer hazard, meaning there is convincing evidence that the medicines can cause cancer under certain conditions. It does not indicate that every patient taking these medicines will develop cancer. Health experts emphasize that the benefits of these treatments often far outweigh the potential risks when they are used appropriately and under medical supervision.
