Acute liver failure is loss of liver function that occurs rapidly — in days or weeks — usually in a person who has no preexisting liver disease. It’s most commonly caused by a hepatitis virus or drugs, such as acetaminophen. Acute liver failure is less common than chronic liver failure, which develops more slowly.

Acute liver failure, also known as fulminant hepatic failure, can cause serious complications, including excessive bleeding and increasing pressure in the brain. It’s a medical emergency that requires hospitalization. Depending on the cause, acute liver failure can sometimes be reversed with treatment. In many situations, though, a liver transplant may be the only cure.