Nonalcoholic steatohepatitis (NASH) is fat buildup in the liver and inflammation of the liver in people who drink little or no alcohol. Because of the inflammation, the liver doesn't work as well as it should. Over time, NASH may get worse and cause scarring of the liver. This can lead to cirrhosis and liver failure.

NASH is the more serious type of nonalcoholic fatty liver disease (NAFLD). In the most common type, nonalcoholic fatty liver (NAFL), fat builds up in the liver but doesn't seem to cause damage. Only some people who have NAFLD have NASH.

The exact cause of NASH is not known, but being obese seems to increase the risk. People who have NASH often have other conditions such as diabetes and high cholesterol. But NASH can occur in a person who has none of these problems.

Many people with NASH have no symptoms and don't know that they have the condition. As NASH gets worse, symptoms may appear. They may include fatigue, weakness, and unexplained weight loss.

To diagnose NASH, a doctor may do blood tests and imaging tests, such as a CT scan. A special type of ultrasound or MRI may be done to see if a liver biopsy is needed.

Treatment focuses on managing related conditions like diabetes and making lifestyle changes, including losing weight if needed, eating a healthy diet, and being more active. A doctor may prescribe medicines for related conditions or to help with weight loss. Weight-loss surgery may be an option for people who have obesity. Treatment may also include stopping the use of medicines that may make symptoms worse. If NASH progresses to cirrhosis, a liver transplant may be needed.