Nonalcoholic steatohepatitis, or NASH, is inflammation of the liver caused by a buildup of fat in liver cells. NASH has features similar to alcohol-induced liver disease, but it occurs in people who do not abuse alcohol.

The exact cause of NASH is not known. NASH is part of a group of liver diseases known as nonalcoholic fatty liver disease (NAFLD). In this group of diseases, fat builds up in the liver and sometimes causes liver damage that gets worse over time (progressive liver damage). People who get NASH are usually middle-aged and overweight or obese and often have other conditions such as diabetes. But NASH can occur in a person who has none of these risk factors.

Many people with NASH have no symptoms and do not know that they have the condition. As NASH gets worse, symptoms may appear and include being tired all the time and having unexplained weight loss and general weakness.

Treatment for NASH may include reducing cholesterol levels, losing weight, and controlling diabetes. Treatment may also include stopping the use of medicines that may make symptoms worse.