Metabolic Dysfunction-Associated Steatohepatitis (MASH)
Overview
Metabolic dysfunction-associated steatohepatitis, or MASH (previously called nonalcoholic steatohepatitis, or NASH) is a dangerously progressive form of fatty liver in which patients have inflammation of the liver and liver damage, attributed to excess fat (steatosis).
About 1.5% to 6.5% of U.S. adults have MASH. One estimate is that nine to 15 million adults have MASH. MASH prevalence is projected to increase by 63% by 2030. MASH may advance to cirrhosis (irreversible scarring of the liver), which increases the risk of hepatocellular cancer (HCC), among other liver related complications, such as ascites (fluid in the abdomen), encephalopathy (confusion) and bleeding from enlarged blood vessels in the esophagus or stomach, known as varices. MASH is currently a leading cause of liver transplant.
It is expected that MASH will become the leading cause of liver transplantation in the United States. Most current data from the United Network of Organ Sharing states that 11,458 liver transplants were performed in 2024. Learn more about understanding the differences between MASLD and MASH.
Learn how MASH can lead to some serious complications.
Symptoms and Causes
Metabolic dysfunction-associated steatohepatitis (MASH, previously called NASH) is not typically associated with symptoms. Some patients, however, may experience symptoms of feeling tired, or pain in the upper right side of the abdomen, where the liver is located. As liver damage worsens, more symptoms may occur.
Learn more about recognizing the signs and symptoms of MASLD and MASH.
Explore who’s at risk and see if children can be impacted.
Diagnosis and Tests
Most people with MASH (previously called NASH) have no symptoms. Medical screening for both MASLD and MASH is not currently a recommended medical guideline. Therefore, it is often discovered during routine blood tests or screenings for another medical condition. Elevated liver enzymes, often found on routine blood tests, is often one of the first signs that patients may have MASH.
People at risk for MASH (as well as MASLD) should discuss tests that could rule out or confirm these conditions. Tests may include blood tests and calculating Body Mass Index (BMI) to determine the best weight for your height. Additional tests may include ultrasound, CT scan, or other image tests that will provide important information about the condition of the liver. Other non-invasive tests may include an Elastography, which is a test that can assess scarring of the liver and help measure the amount of fat in the liver without a painful biopsy.
Another key part of evaluating and diagnosing MASH is to evaluate for other causes of steatosis, or fat, in the liver. One of the most common causes of fat development in the liver is alcohol-associated liver disease. Your healthcare provider may ask you follow up questions on alcohol use.
Learn more about the tests that can diagnose MASLD and MASH.
Management and Treatment
The first line of treatment for MASH (previously called NASH) is weight loss through a combination of weight loss through healthy eating, lower intake of calories and increasing physical activity. Weight loss of 3-5% may improve steatosis (fat) within the liver;; however greater than 10% of weight loss may improve fibrosis of the liver. With respect to exercise, studies have demonstrated that moderate exercise (five times per week for a total of 150 minutes per week) may improve MASH outcomes. Bariatric surgery may also be of benefit for patients.
In March 2024, the US Food and Drug Administration approved the use of resmetirom (Rezdiffra™) for people with NASH and stage 2 or 3 fibrosis (but not cirrhosis) along with eating a healthy diet and participating in regular exercise. This is the first FDA approved medication for steatotic liver disease. Speak with your liver specialist to see if this medication could be right for you.
People with MASH may have several healthcare providers involved with the management and treatment of the disease. The hepatologist (liver specialist) is one member of the healthcare team, but other specialists may be needed as part of an effective treatment plan. These can include nutritionists or dietitians, cardiologists (heart specialists), and endocrinologists (doctors who treat people who have diabetes or thyroid diseases).
Learn how MASH (previously called NASH) is treated differently from MASLD. (previously called NAFLD)
Prevention
MASH (previously called NASH) may be prevented by focusing on choices that will reduce your risk of gaining excess weight and developing type 2 diabetes. If you have excess weight, diabetes or high cholesterol, speak with your healthcare provider about tools to help you manage these conditions.
Physical activity can provide health benefits as well. Many patients with MASH also have cardiovascular (heart) disease, which is a leading cause of death in patients with MASH. Physicial activity may help mitigate the risk for cardiovascular disease and is recommended for all patients with MASH. Getting regular physical activity can help people maintain or lose weight, as well as boost mood. Talk to your healthcare provider about the types of activities that would be safe and healthy for you – and remember, if you do activities that you enjoy, you are more likely to stick with it.
Alcohol can be damaging to the liver. Medical experts recommend that anyone with liver disease avoid drinking all alcohol (beer, wine, or hard liquor) to prevent liver damage from getting worse.
Tobacco products are harmful to the entire body, and as such medical experts recommend avoiding the use of these products.
Outlook and Prognosis
People with MASH have inflammation (swelling) of the liver. In general terms, we know that inflammation of the liver is what leads to the development of scarring (fibrosis) of the liver and puts people at risk for developing cirrhosis. About five to 12% of people with MASH will develop cirrhosis, which in turn increases the risk of needing a liver transplant or developing liver cancer.
Prognosis (likely outcome of a disease) of MASH depends on several various factors – including your own family history (genetics), presence of risk factors, such as type II diabetes, high blood pressure, high cholesterol, weight, and the stage of liver disease at the time of diagnosis (e.g. how much scar tissue is present). As you can see, there are multiple variables that go into evaluating the prognosis of MASH and these variables are highly different in each patient with MASH. Therefore, the best way to find out your own prognosis is to discuss this matter with your healthcare provider.
Living with MASH
People with MASH are encouraged to seek accurate information and develop a connection with others.
1. Ask the right questions to get the most from your doctor’s visit. Use this guide to help begin your conversation with your doctor. View and download our MASH Patient-Physician Discussion Guide.
2. Empower yourself to work with your doctors and medical team to achieve the best health outcomes on your journey with NASH (MASH) by downloading our NASH Patient Bill of Rights. For more details, click here.
3. Connect with other people with MASH by visiting the American Liver Foundation metabolic dysfunction-associated steatohepatitis (MASH), previously called NASH, support group on Facebook. For more details, click here.
Clinical Trials
Clinical trials are research studies that test how well new medical approaches work in people. Before an experimental treatment can be tested on human subjects in a clinical trial, it must have shown benefit in laboratory testing or animal research studies. The most promising treatments are then moved into clinical trials, with the goal of identifying new ways to safely and effectively prevent, screen for, diagnose, or treat a disease.
Speak with your doctor about the ongoing progress and results of these trials to get the most up-to-date information on new treatments. Participating in a clinical trial is a great way to contribute to curing, preventing and treating liver disease and its complications.
Search for a Clinical Trial
Start your search here to find clinical trials that need people like you.
New Nomenclature (Names) of MASH
Please note that MASH (metabolic dysfunction-associated steatohepatitis) used to be called NASH (nonalcoholic steatohepatitis).
Learn about the new nomenclature (terminology) changes to NASH here.
Medically reviewed on April 2025.
Last updated on June 16th, 2025 at 09:40 am