OTTAWA - Several heart and high blood pressure drugs that contain valsartan are being recalled because of a substance that can cause cancer.

Health Canada says the medications were supplied by Zhejiang Huahai Pharmaceuticals of China and that the valsartan used in the affected products contains an impurity known as N-nitrosodimethylamine (NDMA).

NDMA is a potential carcinogen that could cause cancer with long-term exposure. The recall was issued by the manufacturers of several drugs involving five companies.

Drugs containing valsartan are used to treat high blood pressure and help prevent heart attacks and stroke. They are also used by patients who have had heart failure or a recent heart attack.

Health Canada says anyone taking medication that contains valsartan should continue unless told to stop by their doctor or pharmacist.

But the agency also says patients taking the drug should check with their pharmacist to learn if their medicine is being recalled.