People taking the cholesterol-lowering medication Zocor should be aware they may be at risk for muscle problems if taking a high dose or using certain other medications and foods.

Health Canada said Tuesday that people taking Zocor or simvastatin within the recommended dose range are at increased risk for two muscle problems.

Zocor is used to lower the levels of cholesterol and triglcerides in the blood. (Mel Evans/Associated Press)

The drug, which is also available in generic forms, is used to lower the levels of cholesterol and fatty substances called triglycerides in blood and to reduce the health risks associated with coronary heart disease, the department said.

Those taking 80 milligrams of the medication are at increased risk of rhabdomyolysis — a type of muscle injury that in severe cases can lead to kidney failure or death — particularly in the first year of treatment, Health Canada said in a letter to health professionals. Those patients may also be at risk of myopathy, a type of muscle weakness.

The 80-milligram dose is only for patients who've been taking that dose chronically with no muscle problems or those at high risk of heart disease who aren't able to take other cholesterol-lowering drugs, Health Canada said.

Since an increased risk is also seen when simvastatin is taken with grapefruit juice, the department recommended that patients avoid drinking more than one litre of grapefruit juice a day.

The information for health professionals includes details on what medications are contradicted with Zocor.

Health Canada said the advisory was released in consultation with Merck Canada.