High cholesterol levels do not usually cause any obvious symptoms. As a result, people are often not aware that they have high cholesterol until a screening test shows abnormal results.

High cholesterol levels can have harmful effects on the body, but people can take steps to lower them. In some cases, doctors may also prescribe medications.

Keep reading to learn about the effects of high cholesterol, as well as the causes and treatment options.

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Photo editing by Stephen Kelly; Robert DiScalfani/Getty Images

Cholesterol is a fat-like substance that the liver makes. Its functions include:

  • being a component of bile acids, which aid in the digestion of fatty foods
  • being the precursor of steroid hormones
  • helping the skin make vitamin D when it has exposure to sunlight
  • playing a key role in cell membrane health

As the body can make all of the cholesterol that it uses for these functions, people do not need to get it from their diet. As long as the body has cholesterol in the right amounts, this substance is beneficial. However, it becomes a risk factor for several conditions when there is too much of it.

The Centers for Disease Control and Prevention (CDC) note that the two main types of cholesterol are:

Low-density lipoprotein (LDL) cholesterol

People sometimes refer to this as “bad” cholesterol. High LDL levels cause plaque to build up in the blood vessels, narrowing them. This narrowing can lead to stroke, heart attack, and other problems.

High-density lipoprotein (HDL) cholesterol

People sometimes call this “good” cholesterol. Therefore, low HDL levels may also be a health concern.

According to the National Heart, Lung, and Blood Institute (NHLBI), high levels of LDL cholesterol usually do not cause symptoms. As a result, individuals are often unaware of the high levels until they get their results from a cholesterol screening.

However, the NHLBI note that some people with very high levels may experience grayish-white rings around the corneas in their eyes or fatty bumps on their skin.

The CDC state that about 38% of people in the United States have high cholesterol, so it is important to have a screening periodically. The diagnosis and treatment of this condition can help prevent serious problems.

Over time, high cholesterol may lead to the development of atherosclerosis, note the NHLBI.

In this condition, plaque accumulates in blood vessels throughout the body. Once the plaque buildup obstructs blood flow, it can lead to the following:

A 2014 study found that high cholesterol and high blood pressure may work together to contribute to the development of coronary heart disease. The authors reported that people with the highest cholesterol and blood pressure levels had the greatest risk of death from the condition.

Doctors will generally categorize a person’s total cholesterol according to these ranges:

Less than 200 milligrams/deciliter (mg/dl)Desirable
200–239 mg/dlBorderline high
240 mg/dl and aboveHigh

The optimal levels of LDL cholesterol are less than 100 mg/dl, while HDL cholesterol levels should ideally be 60 mg/dl or higher.

The NHLBI report that the following factors may cause abnormal cholesterol levels:

  • Diet and lifestyle: These factors, which are the most common cause, include physical inactivity, smoking, and eating an imbalanced diet.
  • Certain medications: Some drugs can increase levels of LDL cholesterol or decrease levels of HDL cholesterol. Examples include chemotherapy drugs for cancer and beta-blockers for reducing high blood pressure.
  • Genes: People may inherit a tendency to have high levels of LDL cholesterol.

In addition, some conditions are associated with abnormal levels of cholesterol. These conditions include:

  • Diabetes: High cholesterol is common in people with this disease.
  • Hypothyroidism: This condition happens when the thyroid gland does not make enough hormones. Signs of the condition include high levels of LDL cholesterol and total cholesterol.
  • Metabolic syndrome: Metabolic syndrome is a group of risk factors that increase the likelihood of heart disease, stroke, and diabetes. A low level of HDL cholesterol is one of the risk factors.

The American Heart Association (AHA) recommend that people follow the habits below to lower their cholesterol.

Eat a heart-healthy diet

A heart-healthy diet includes fruits, vegetables, whole grains, nuts, fish, poultry, low fat dairy products, and nontropical vegetable oils. It also involves limiting foods high in salt and sugar, along with red and processed meats.

The best dietary practice to lower cholesterol is to avoid saturated and trans fats, which are present in various food sources, such as fatty meats and packaged foods.

Exercise regularly

A sedentary lifestyle lowers HDL cholesterol — an effect that raises LDL cholesterol. Getting at least 150 minutes of moderate intensity exercise per week can lower total cholesterol and blood pressure.

Quit smoking, if applicable

When a person with high cholesterol smokes, it further increases their risk of coronary artery disease.

Quitting smoking can raise HDL cholesterol and lower LDL cholesterol.

As secondhand smoke is also harmful, nonsmokers should avoid exposure where possible.

Reach or maintain a moderate weight

Overweight and obesity raise LDL cholesterol and lower HDL cholesterol. Losing as little as 5–10% of body weight can improve cholesterol levels.

Doctors prescribe several types of medications to lower cholesterol. The CDC list the following:

  • Statins: These drugs reduce the liver’s production of LDL cholesterol and increase its ability to remove this substance.
  • Niacin: This B vitamin increases HDL cholesterol while decreasing LDL cholesterol.
  • Bile acid sequestrants: These molecules remove bile acids, which helps decrease cholesterol.
  • Injectable medicines: Doctors mainly use these drugs for people with a genetic condition that causes very high levels of LDL cholesterol.

Anyone with cholesterol levels that do not fall within the desirable range should see a doctor.

The person’s treatment options will depend on how high their cholesterol levels are and whether they have other risk factors for heart attack or stroke.

The CDC report that doctors may prescribe drugs for people who have an LDL cholesterol level of at least 190 mg/dl without risk factors or at least 70 mg/dl with risk factors.

As there are no symptoms of high cholesterol, people may have it without being aware.

The most common cause is unhealthy habits, so doctors typically recommend making certain lifestyle changes. These include practices such as eating a nutritious diet, getting regular exercise, and quitting smoking.

Doctors also prescribe medications for certain individuals. A person with high cholesterol should visit their doctor to get a personalized treatment plan.