Health Canada says a recall on certain medication used to treat high blood pressure and heart failure is being expanded because the drugs may contain a substance that can increase the risk of cancer.

The agency says eight additional valsartan medications are being recalled as a precautionary measure.

Health Canada says a recall of 28 valsartan medications was announced last month because the drugs contained an impurity known as NDMA, a potential carcinogen that can cause cancer with long-term exposure.

It says all of the recalled products use a valsartan ingredient manufactured by a pharmaceutical company in China.

The agency says anyone taking affected valsartan medications should contact their health-care provider to discuss treatment options.

It also says patients should continue taking their medications unless they have been advised by their health-care provider to stop.