Valisure, an online pharmacy licensed in 37 states, told the FDA it found another cancer-causing chemical in valsartan, a widely prescribed heart drug, according to Bloomberg.
The pharmacy discovered an impurity called dimethylformamide, which is classified as a probable carcinogen by the World Health Organization.
The impurity was found in valsartan manufactured by five companies, including Novartis. The online pharmacy recommended a recall.
The FDA will evaluate Valisure's findings.
Dozens of forms of generic valsartan have been recalled since July 2018, after an impurity known as N-Nitrosodimethylamine was detected in a version of the drug.
Dimethylformamide is the fourth potential carcinogen to be found in generic versions of the heart pills.