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What is hepatitis?

Thumbnail image of the liverHepatitis is an inflammation of the liver that is most commonly caused by viruses but may also be due to chemicals, drugs, alcohol, inherited diseases, or autoimmune disease. The inflammation 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, liver cancer, or 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, manufacturing 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 excrete. Inflammation may (in severe cases) interfere with these processes and allow potentially toxic substances to accumulate.

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.
Chemical or drug induced The liver processes many substances for the body to use and/or then eliminate. Some of these substances are toxic to the liver and can result in 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 within liver cells, causing hepatitis. Acute or chronic exposure to alcohol, acetaminophen
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 Sjorgren syndrome

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