Statins are very commonly used to lower cholesterol in patients who are at increased risk for cardiovascular disease.
They also may have other beneficial effects, currently being studied, such as being anti-inflammatory.
There are occasional side effects including muscle pains (myalgias) and rarely liver dysfunction, which should be closely monitored by you and your prescribing physician.
There has been some evidence that statins can increase your risk for diabetes, but in most cases the benefits of preventing cardiovascular disease outweigh that risk.
The amount of cholesterol lowering depends on the type and dose of statin prescribed.