Statins are drugs that can lower your cholesterol. They work by blocking a substance that your body needs to make cholesterol.

Lowering cholesterol isn't the only benefit of taking a statin. These medicines also have been linked to a lower risk of heart disease and stroke. Statins also may help reduce the risk of certain blood clots.

A number of statins are available for use in the United States. They include:

• Atorvastatin (Lipitor).
• Fluvastin (Lescol XL).
• Lovastatin (Altoprev).
• Pitavastatin (Livalo).
• Pravastatin.
• Rosuvastatin (Crestor).
• Simvastatin (Zocor).

Sometimes, a statin is combined with another heart medicine. Examples are atorvastatin-amlodipine (Caduet) and ezetimibe-simvastatin (Vytorin).

Whether you need to be on a statin depends on your cholesterol levels and other risk factors for heart and blood vessel disease. Your healthcare professional will consider all of your risk factors for heart attacks and strokes before prescribing a statin.

Knowing your cholesterol numbers is a good place to start.

• Total cholesterol. Most people should try to keep their total cholesterol below 200 milligrams per deciliter (mg/dL), or 5.2 millimoles per liter (mmol/L).
• Low-density lipoprotein (LDL) cholesterol. Aim to keep this "bad" cholesterol under 100 mg/dL, or 2.6 mmol/L. If you have a history of heart attacks or are at a very high risk of a heart attack or stroke, you may need to aim even lower (below 70 mg/dL, or 1.8 mmol/L).

Your long-term risk of a heart attack or stroke is the most important thing that your healthcare professional will keep in mind when thinking about statin treatment. If your risk is very low, you probably won't need a statin, unless your LDL is above 190 mg/dL (4.92 mmol/L).

If your risk is very high — for example, you've had a heart attack in the past — a statin may be helpful even if you don't have high cholesterol.

Besides cholesterol, other risk factors for heart disease and stroke are:

• Tobacco use.
• Lack of exercise.
• High blood pressure.
• Diabetes.
• Overweight or obesity.
• Narrowed arteries in your neck, arms or legs. This is known as peripheral artery disease.
• Family history of heart disease, especially before the age of 55 in male relatives or before 65 in female relatives.
• Older age.

Your healthcare professional may use an online tool or calculator to better understand your long-term risks of developing heart disease and whether a statin may be right for you. These tools can help predict your chances of having a heart attack in the next 10 to 30 years. The formulas in these tools often consider your cholesterol levels, age, race, sex, smoking habits and health conditions.

Not everyone with a heart condition needs to use a statin. Guidelines from the U.S. Preventive Services Task Force, American College of Cardiology and American Heart Association suggest four main groups of people who may be helped by statins:

• People who have one or more cardiovascular disease risk factors and a higher 10-year risk of a heart attack. This group includes people who have diabetes, high cholesterol or high blood pressure, or who smoke and whose 10-year risk of a heart attack is 10% or higher.
• People who already have cardiovascular disease related to hardening of the arteries. This group includes people who have had heart attacks, strokes caused by blockages in a blood vessel, ministrokes, called transient ischemic attacks, blocked arteries in the legs or neck, or prior surgery to open or replace coronary arteries.
• People who have very high LDL ("bad") cholesterol. This group includes adults who have LDL cholesterol levels of 190 mg/dL (4.92 mmol/L) or higher. Many of these patients have a condition called familial hyperlipidemia and are at a significantly higher risk of heart attacks and strokes.
• People who have diabetes. This group includes adults 40 to 75 who have diabetes and an LDL cholesterol level between 70 and 189 mg/dL (1.8 and 4.9 mmol/L), especially if they have evidence of blood vessel disease or other risk factors for heart disease such as high blood pressure or smoking.

The U.S. Preventive Services Task Force recommends low- to moderate-dose statins in adults ages 40 to 75 who have one or more risk factors for heart and blood vessel disease and at least a 10% chance of having a cardiovascular disease event in the next 10 years.

Lifestyle changes are key to reduce your risk of heart disease, whether you take a statin or not. To reduce your risk:

• Quit smoking and avoid secondhand smoke.
• Eat a healthy diet rich in vegetables, fruits, legumes, fish and whole grains.
• Limit the amount of saturated fat, trans fat, refined carbohydrates and salt you eat.
• Be physically active more often and sit less.
• Maintain a healthy weight.

If your cholesterol — particularly the LDL ("bad") type — stays high after you make healthy lifestyle changes, statins might be an option for you.

You may think that if your cholesterol goes down, you don't need a statin anymore. But if the medicine helped lower your cholesterol, you'll likely need to stay on it long term to keep your cholesterol down. If you make significant changes to your diet or lose a lot of weight, talk to your healthcare professional about whether it might be possible to control your cholesterol without medicine.

Statins are tolerated well by most people, but they can have side effects. Some side effects go away as the body adjusts to the medicine.

But tell your healthcare professional about any unusual symptoms you might have after starting statin therapy. They may want to decrease your dose or try a different statin. Never stop taking a statin without talking to your healthcare team first.

Commonly reported side effects of statins include:

• Headaches.
• Nausea.
• Mild increase in sugar levels.
• Muscle and joint aches.

However, studies comparing statins to a fake pill, called a placebo, have found a very small difference in the number of people reporting muscle aches between the groups.

For people who already have high sugar levels, the mild increase in blood sugar levels may lead to being diagnosed with type 2 diabetes. However, the benefit of taking a statin may outweigh that risk. People with diabetes who take statins have much lower risks of heart attacks.

Rarely, statins can cause more-serious side effects such as:

• Muscle cell damage. Very rarely, high-dose statin use can cause muscle cells to break down and release a protein called myoglobin into the bloodstream. This can lead to severe muscle pain and kidney damage.
• Liver damage. Occasionally, statin use causes an increase in liver enzymes. If the increase is mild, you can continue to take the medicine. Low to moderate doses of statins don't appear to raise liver enzyme levels severely.

Some people have reported memory loss and thinking problems after using statins. But a number of studies haven't been able to find any evidence to prove that statins actually cause these problems. Other studies suggest that statins may help prevent these issues.

Also, ask your healthcare professional if the statin you use will interact with any other medicines or supplements you take.

When thinking about whether you should take statins for high cholesterol, ask yourself these questions:

• Do I have other risk factors for heart and blood vessel disease?
• Am I willing and able to make lifestyle changes to improve my health?
• Am I concerned about taking a pill every day, perhaps for the rest of my life?
• Am I concerned about statins' side effects or interactions with other medicines?

It's important to consider your medical reasons, personal values, lifestyle choices and any concerns when choosing a treatment. Talk to your healthcare professional about your total risk of heart and blood vessel disease and personal preferences before making a decision about statin therapy. And if the conclusion is that you cannot take statins, be reassured that there are other medications that can lower your cholesterol.