Simvastatin is a medication used to lower "bad" cholesterol and fats (such as LDL, triglycerides) and raise "good" cholesterol (HDL) in the blood. It belongs to a group of drugs called HMG-CoA reductase inhibitors, or statins, which work by blocking an enzyme that is needed to make cholesterol. Simvastatin is used together with a proper diet, weight-loss, and exercise to reduce the risk of heart attack and stroke and to decrease the chance that heart surgery will be needed in people who have heart disease or who are at risk of developing heart disease. It may also help prevent medical problems (e.g., heart or blood vessel problems, heart attacks, or strokes) caused by clogged blood vessels. Simvastatin may also be used to decrease the amount of cholesterol and other fatty substances in the blood in children and teenagers 10 to 17 years of age who have familial heterozygous hypercholesterolemia (an inherited condition in which cholesterol cannot be removed from the body normally) .

It is important to take simvastatin as directed by a doctor, usually once daily in the evening, with or without food. A very small number of people taking simvastatin may have mild memory problems or confusion, and rarely, statins may cause or worsen diabetes. Before taking simvastatin, it is important to tell your doctor or pharmacist if you are allergic to it or if you have any other allergies, liver disease, kidney disease, alcohol use, or are taking other medications that may affect how simvastatin works.