Statins are drugs used to lower cholesterol. Your body needs some cholesterol to work properly. But if you have too much in your blood, it can stick to the walls of your arteries and narrow or even block them.

If diet and exercise don't reduce your cholesterol levels, you may need to take cholesterol medicine. Often, this medicine is a statin. Statins interfere with the production of cholesterol in your liver. They lower LDL (bad) cholesterol levels and raise HDL (good) cholesterol levels. This can slow the formation of plaques in your arteries.

Statins are relatively safe for most people. But they are not recommended for pregnant patients or those with active or chronic liver disease. They can also cause serious muscle problems. Some statins also interact adversely with other drugs. You may have fewer side effects with one statin drug than another.

Researchers are also studying the use of statins for other conditions.

Most heart attacks and strokes are preventable by practicing a healthy lifestyle, and when necessary, taking medications to lower blood pressure or cholesterol or to help quit smoking. Statins, when used as indicated, can dramatically reduce a person’s risk of having a heart attack or stroke, but millions of people are missing that opportunity. Some clinicians may miss prescribing a statin to a person who can benefit. Many times, individuals stop or do not start taking a statin due to concerns about side effects. The good news is that understanding your individual benefits and risks and working through your concerns with your clinician can help you prevent heart attacks and strokes and enjoy a longer, healthier life.

Statins are a class of medicines used to lower cholesterol. While some of the cholesterol in your blood comes from food, most is made by the liver. Statins work by reducing the amount of cholesterol made by the liver and helping the liver remove cholesterol that is already in the blood. Statins may also reduce inflammation in the artery walls. This can lead to blockages that damage organs such as the heart and brain.

Scientific studies and years of use all over the world have proven that statins, when used as indicated, reduce a person’s chances of having a heart attack or stroke; needing surgery, angioplasty, or stenting to improve blood flow in an artery; and dying from a heart attack. The higher a person’s risk of having a heart attack or stroke, the stronger the benefit of the statin. The benefit increases the longer the statin is taken. In general, taking a statin can cut a person’s risk of a heart attack or stroke in half.

Serious risks are rare. Studies involving thousands of people show no differences in muscle aches, liver abnormalities, dementia, memory problems, or cancer between those taking a statin and those on an inactive pill. Despite these findings, just over one in four people (29%) taking a statin describes some symptom, most commonly muscle aches or weakness. It is important to note that muscle-related symptoms are also common with aging and in active adults who are not on statins. Very uncommon risks associated with statins including a type of stroke caused by bleeding, muscle damage that can usually be detected with a blood test, and increased blood sugar levels or new-onset diabetes in those who are prone to developing diabetes. The large benefit of taking statins to prevent heart attacks and strokes likely outweighs the small risk associated with an elevated blood sugar level.

Side effects from statins can frequently be managed by adjustments in the dose or by choosing a different statin drug. Before stopping or changing your medication, please discuss your concerns with your clinician, who can help determine the likelihood that symptoms are related to the statin. Together you can map out a practical plan to keep you safe from heart attack and stroke.

People who have had a heart attack or stroke, who have diabetes or very high “bad” cholesterol levels, and who are at high risk for heart disease or stroke due to other factors like high blood pressure will live healthier and longer lives by taking a statin. Because the degree of the benefit from a statin varies with your chances of having a heart attack or stroke, it is important to discuss your individual risks and preferences with your clinician. Together you can make a good decision for your healthiest future.

• What are my “good” and “bad” cholesterol levels?
• What is my personal risk of a heart attack or stroke?
• For me, is the benefit of taking a statin worth the risk?
• How—and how soon—will we know that the statin is working for me?
• Can I quit or decrease the statin if I lose weight? Exercise daily? Eat differently?
• How soon could I feel a side effect, and what should I do about it?
• How often will I need follow-up blood tests or check-ups?
• What is the next step if a statin doesn’t work or if I can’t take it?

You go to the gym faithfully, and try to watch your diet. But after your annual physical, you find out that your blood cholesterol is surprisingly high. Your doctor calls you back to discuss taking a medication known as a statin.

Here are some commonly asked questions about cholesterol and statins.

1. What are statins? How do they work?

Statins are a class of medicines used to lower cholesterol in the blood. Most of the cholesterol in your blood is made by the liver. Statins work by reducing the amount of cholesterol made by the liver and by helping the liver remove cholesterol that is already in the blood.

According to James P. Smith, M.D., M.S., deputy director of the Division of Metabolism and Endocrinology at the U.S. Food and Drug Administration (FDA), “An important first step is to have a discussion with your healthcare provider about your risk of having heart disease or a stroke, how a statin would reduce that risk, and any side effects that you should consider.”

2. Why is it important to keep cholesterol levels in the blood low?

Your body needs cholesterol, but too much of it in your blood can lead to buildup on the walls of your arteries (this buildup is called “plaque”), putting you at higher risk for heart disease and stroke. According to the Centers for Disease Control and Prevention (CDC), heart disease is the leading cause of death for both men and women in the United States.

3. I’ve heard about “good” and “bad” cholesterol. What’s the difference?

Cholesterol is carried in the bloodstream on different types of particles, called lipoproteins. The majority is carried on low-density lipoprotein (LDL) particles and is sometimes referred to as “bad” cholesterol, because high levels of LDL particles can lead to heart disease and stroke. High-density lipoprotein (HDL) particles, on the other hand, carry cholesterol back to the liver for removal from the body. Since people with higher levels of HDL-cholesterol tend to have a lower risk of heart disease, this is sometimes referred to as “good” cholesterol. Your healthcare provider should help you interpret what your numbers mean for your cardiovascular health.

4. I thought a healthy diet and regular exercise would keep my cholesterol in check. Not so?

“A heart-healthy diet, regular physical activity, and maintaining a healthy weight are all very important components of a lifestyle that can help lower cholesterol and reduce the risk of heart disease and stroke,” says Smith. “But other factors that are out of our control, such as genetics, also play a role. For many people, cholesterol simply cannot be lowered enough by lifestyle changes alone.”

For people who are at increased risk of having a heart attack or stroke, statins may be recommended even when cholesterol levels might not seem too high. “Statins have a well-established track record for reducing the risk for heart attacks and strokes,” Smith says. “Whether or not a statin is appropriate for a specific patient should involve a conversation between the patient and his or her healthcare provider.”

5. I’ve heard that there are some risks to taking statins. Should I be worried?

Statins are typically very well tolerated. Two risks that patients may be aware of are muscle-related complaints and an increased risk of developing type 2 diabetes. “Muscle complaints are quite common even among people not taking statins, so it is important to have your healthcare provider evaluate any symptoms before stopping your medication,” Smith explains. “It is rare for statins to cause serious muscle problems.”

Similarly, the risk of developing diabetes as a result of a statin is small. “The benefits of statins in reducing heart attacks and strokes should generally outweigh this small increased risk,” Smith says.

6. I’ve heard you shouldn’t drink grapefruit juice if you’re taking a statin. Is that true?

Grapefruit juice and fresh grapefruit can affect the way some medicines work. That’s true with certain statins, too—but only some of them. In addition, other medications can also interact with statins. Smith advises patients ensure that their healthcare provider and pharmacist know about all the prescription and non-prescription medications they take.