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What is hepatitis?

Thumbnail image of the liverHepatitis is an inflammation of the liver. Most often, hepatitis is caused by infection with certain viruses. However, liver inflammation can also result from exposure to chemicals, over-the-counter or prescription drugs, heavy alcohol use, inherited diseases, autoimmune disease, or fatty buildup in the liver.

Hepatitis can be acute, flaring up and then resolving within a few weeks to months, or chronic, enduring over many years. Chronic hepatitis may persist for 20 years or more before causing significant symptoms related to progressive liver damage, such as cirrhosis and liver cancer, and can cause death.

The liver is a vital organ located in the upper right-hand side of the abdomen. It performs many functions in the body, including processing the body's nutrients, producing bile to help digest fats, synthesizing many important proteins, regulating blood clotting, and breaking down potentially toxic substances into harmless ones that the body can use or eliminate. In severe cases, liver inflammation may interfere with these processes and allow potentially toxic substances to build up.

The following table summarizes some common types of hepatitis. Click on the links to read more about the various types.

Type of Hepatitis Description Examples of Causes
Viral Infection with one of the hepatitis viruses causes inflammation; may be acute or chronic depending on virus. In the U.S., most common causes are hepatitis A, B and C viruses.
Toxic or drug-induced The liver processes many substances for the body to use and/or eliminate. The byproducts of this process can be toxic to the liver and may cause hepatitis. In other cases, hepatitis occurs with a drug that is not directly toxic to the liver but the body recognizes the drug as foreign and attacks it, causing hepatitis. Alcohol, over-the-counter pain relievers, prescription drugs, herbal and vitamin supplements, industrial chemicals
Inherited Certain gene mutations that are passed from one generation to the next can result in a disease that damages the liver, causing hepatitis. Wilson disease, hemochromatosis, alpha-1 antitrypsin deficiency
Non-alcoholic fatty liver Fat deposited in the liver cells in increasing amounts can lead to inflammation and liver injury, causing hepatitis. Associated with metabolic syndrome
Autoimmune The body's immune system inappropriately produces antibodies directed against liver tissue, causing hepatitis. Sometimes associated with other autoimmune diseases, such as type 1 diabetes, Hashimoto thyroiditis, pernicious anemia, or Sjögren syndrome

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