MASH is the form of fatty liver disease in which extra fat in the liver is accompanied by inflammation and injury to liver cells, which is what can lead over time to scarring, cirrhosis and liver cancer [6,11].
This page provides general information. It does not replace advice from a doctor or another qualified healthcare professional.
MASH stands for metabolic dysfunction-associated steatohepatitis. It is a condition of the liver in which three things happen at once [6,11]:
The third element is the point. Fat alone is common and often harmless. Fat plus inflammation plus injury sets off a repair cycle that lays down scar tissue, and scarring leads to cirrhosis and liver cancer [16,22].
The umbrella condition is MASLD, metabolic dysfunction-associated steatotic liver disease: fat in the liver in someone who also has at least one of five cardiometabolic features, once heavy alcohol use and other causes are ruled out [24]. Most people with MASLD have fat with little or no inflammation, and that form usually does not progress [6]. MASH is the smaller group where inflammation and injury are present too, and nobody can tell them apart by how they feel [6]. See also the trialport guide to fatty liver disease and MASLD.
In June 2023 a consensus of three international liver associations, drawing on 236 panelists from 56 countries, renamed NAFLD as MASLD and NASH as MASH [1]. The old naming defined the condition by exclusion, by what it was not, and the words were felt to be stigmatizing, by 61 percent of those surveyed for “nonalcoholic” and 66 percent for “fatty” [1]. The new names describe it through the metabolic features that drive it [1,24]. Readers will still meet NASH and NAFLD in older leaflets, on results and in conversation, and they mean the same conditions. The United Kingdom’s guideline was renamed in July 2026 [2].
Around 32 percent of adults worldwide are estimated to have MASLD and around 5 percent to have MASH, with MASLD at 30 percent across the European Union and the United Kingdom [23]. United States government estimates put MASLD at about 24 percent of adults and MASH at 1.5 to 6.5 percent [6].
These are estimates, not counts: confirming MASH has historically needed a liver biopsy, which cannot be done across a population, so figures vary and many go undiagnosed [5,19].
Rates run far higher in some groups: MASH is estimated at 33.5 percent among people living with overweight or obesity and 31.6 percent among people with type 2 diabetes [23]. More than a third of Australians are thought to have fatty liver disease [26], and in a Dubai study of 94,754 adults, half screened positive for MASLD risk factors [25].
MASLD including MASH is now the second leading cause of end-stage liver disease and liver transplantation in Europe [23].
MASH begins with a problem in metabolism, the way the body takes and stores energy from food. Fat builds up inside liver cells, damages and inflames them, and the repeated repair that follows lays down scar tissue [16].
The metabolic conditions involved are type 2 diabetes or prediabetes, overweight or obesity, high blood pressure and abnormal blood fats. Doctors use the term metabolic syndrome for any three of a large waist, high triglycerides, low HDL cholesterol, high blood pressure and raised blood glucose [7]. Genes, meaning small differences in the instructions inside cells, also matter and may help explain why rates differ between ethnic groups [6,7]. Risk rises with age, is higher in men, and increases after menopause in women [16].
Body weight is part of the picture and not the whole picture: up to 1 in 5 people with MASLD have a body mass index in the healthy range [16]. Nobody chooses to develop this condition, and weight is shaped by far more than personal choices [16]. Experts still do not know why some people with liver fat develop MASH and others never do [6].
This is the most important thing on the page. MASH is usually silent. A person can have cirrhosis caused by MASH and have no symptoms at all [7].
Early symptoms, where they appear, are vague: tiredness, and discomfort in the upper right of the abdomen where the liver sits [7,17]. Neither is specific to the liver, and many people with MASH feel well [17], so asking a doctor about tests beats waiting for a symptom.
When to seek urgent help. Symptoms of advanced liver disease are the exception, and most people with MASH will never experience them. Tell a doctor straight away, or seek urgent care, if any of these appear: yellowing of the skin or the whites of the eyes, which is harder to see on black or brown skin; vomiting blood; black, tarry stools; confusion or unusual changes in mood; swelling of the abdomen, legs or feet; bruising very easily; dark urine; or losing weight without trying [17,26].
No single test diagnoses MASH, part of why it is missed [19]. Diagnosis starts with a family doctor, who asks about other conditions, medicines and alcohol intake to rule out alcohol-related liver disease, and moves to a liver specialist, called a hepatologist, if results suggest advanced scarring [2,19].
Blood tests, with an important caveat. Raised liver enzymes can be a clue [8]. Normal ones prove nothing. More than 80 percent of people with MASLD have normal routine liver blood tests, and United Kingdom guidance says plainly that those tests should not be used to rule MASLD out or to check for advanced scarring [2,5].
Fibrosis scores combine several results into one number. FIB-4 uses age, two liver enzymes and the platelet count, and a result below about 1.3 is usually low risk and above 2.67 high risk [19,25]. United Kingdom guidance suggests the enhanced liver fibrosis test, treating a score of 10.51 or above as advanced fibrosis [2].
Scans. Ultrasound shows fat but not inflammation or scarring. Transient elastography, often called FibroScan, is a quick painless scan of liver stiffness, which reflects scarring [8,19].
Liver biopsy remains the only test that can prove MASH, and its role is shrinking [8]. Guidelines now use blood scores first and imaging second, keeping biopsy for unclear or high-risk cases, and the newest MASH medicine can be prescribed on either route [8,14,24].
Treatment has two aims: to stop the condition getting worse, and to let the liver repair what it can [20]. Damage can be slowed and sometimes partly reversed, especially at earlier stages [18,20].
Everyday changes. Reducing liver fat addresses the root cause, and research shows that reducing body weight lowers liver fat, with larger reductions also lowering inflammation and scarring [9]. Weight loss should be gradual, since rapid loss can make liver disease worse [9]. It is genuinely hard, and a doctor can refer someone to a dietitian or local program [20]. Physical activity helps on its own terms, reducing liver fat even when body weight does not change, with the clearest effect at around 150 minutes of brisk walking a week [9,24].
Resmetirom is the first medicine approved specifically for MASH. It is a daily tablet that activates a receptor in liver cells to increase fat breakdown, reducing inflammation and scarring [11]. United States regulators approved it in March 2024 and European regulators in August 2025, both conditionally, for adults with non-cirrhotic MASH and moderate to advanced fibrosis [10,11]. What it does not do is also on the record. There is no evidence yet that it reduces liver transplants or improves survival, long-term studies are still running, and it is not for people with decompensated cirrhosis [10,11]. The most common side effects are diarrhea and nausea [10]. It is under review and not yet available in the United Kingdom [21].
GLP-1 receptor agonists copy a natural hormone that helps control blood sugar and appetite [21]. In August 2025 United States regulators gave semaglutide accelerated approval for the same group [12]. In the European Union its authorized indication covers weight management, not MASH [13], and in the United Kingdom it is under review [21].
Other options. Bariatric surgery is not a direct MASH treatment, and it can improve the liver in some people with MASLD and obesity [14,20]. Where advanced fibrosis is present, United Kingdom specialists may also consider pioglitazone or vitamin E [3]. Availability differs by country.
Treating what sits alongside it. Managing type 2 diabetes, blood pressure and cholesterol is central, since the greatest risk to overall health here is often heart attack and stroke [18,20]. People taking statins should keep taking them [4]. Guidance asks clinicians to explain staying within national low-risk alcohol limits, and to advise stopping completely where advanced fibrosis or cirrhosis is present [2,20].
Where cirrhosis has developed, scans for liver cancer are usually offered every six months, and European guidance also recommends monitoring for raised pressure in the liver’s blood supply [14,22]. A transplant may be considered if the liver cannot recover [14].
Monitoring continues even when nothing feels wrong, with retesting every few years at low risk and again after starting treatment [2,3]. No complementary or alternative medicine has been shown to treat this condition and some can harm the liver. Smoking speeds liver disease up, so stopping helps [20]. A diagnosis carrying assumptions about weight and drinking can be hard to talk about, and liver charities run free helplines [1,20].
Clinical trials test whether a treatment works and is safe. Deciding whether to look into one is personal, and it helps to take it in steps.
It is worth being clear on what a study involves:
MASH studies often run a year or longer, because liver changes are slow, and many involve fasting blood tests, scans and a record of activity or food between visits.
Every trial has rules about who can take part, called eligibility criteria. For a MASH study they might include MASH confirmed on a recent liver biopsy or by validated non-invasive tests, a fibrosis stage inside a set range with cirrhosis excluded, a FIB-4 or liver stiffness reading between set limits, stable body weight beforehand, blood sugar inside a stated range for people with type 2 diabetes, alcohol below a stated limit, no other cause of liver disease, and staying on a steady dose of current medicines.
trialport’s medifit helps people consider information related to possible medical suitability. It does not diagnose a condition, confirm eligibility or replace formal screening by the study team.
Explore MASH clinical trials through trialport
A study can look right on paper and still be hard in practice. Worth thinking through:
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Study status checked: 3 August 2026. Research moves quickly and what is being studied changes, so this list will date. For current information, search at app.trialport.com.
In the United Kingdom, Liver UK, formerly the British Liver Trust, has the clearest patient information on this condition and a free nurse-led helpline [15,20], and NICE guideline NG49 sets out what care should look like [2]. In the United States, the NIDDK pages on fatty liver disease are detailed and government-reviewed, though last reviewed in 2021 and so predating the renaming and the first approved medicine [6,9]. In Australia, the Liver Foundation runs a liver nurse line [26]. Coverage is thinner elsewhere, and a hospital liver clinic is the best starting point.
Dan Marino, the American football quarterback and Pro Football Hall of Fame member, revealed in September 2025 that he has MASH. He was diagnosed in 2007 after mentioning fatigue at a routine check-up, was told it could be reversible, and has since managed it with regular activity and yearly scans [27]. He had almost no symptoms, which is how most cases present.
Is MASH the same as NASH?
Yes. NASH was renamed MASH in 2023, when NAFLD became MASLD, and both names remain in use [1,15].
What is the difference between MASLD and MASH?
MASLD means fat in the liver alongside metabolic features [24]. MASH is the form where inflammation and liver-cell injury are present too, which drives scarring [6].
Do I have MASH if my liver blood tests are normal?
Normal results do not rule it out. More than 80 percent of people with MASLD have normal routine liver blood tests, and guidance says those tests should not be used to rule the condition out [2,5].
Is this caused by drinking?
No. MASH is defined by metabolic features and the definition excludes heavy alcohol use [24]. Alcohol still strains a liver already working hard, so guidance asks people to stay within national low-risk limits [2,20].
Did I bring this on myself?
No. Nobody chooses to develop this condition, weight is shaped by far more than personal choices, and up to 1 in 5 people with MASLD have a body mass index in the healthy range [16]. Stigma in the old names is one reason they changed [1].
Is there a medicine for it?
Yes, for some people. Resmetirom is approved in the United States and the European Union for adults with non-cirrhotic MASH and moderate to advanced scarring, and semaglutide in the United States [10,11,12]. Neither is approved for MASH in the United Kingdom [21].
Written by: trialport editorial team
Reviewed by: Keith Berelowitz, Founder and CEO, trialport
Reviewed on: 3 August 2026
Next review due: 3 August 2027
References last checked: 3 August 2026