What Is MASH?
Published Jul 1, 2026 · 5 minute read
MASH is the liver disease that keeps appearing in headlines about new GLP-1 drugs. If you have seen pemvidutide, survodutide, or efinopegdutide described as “MASH drugs” and wondered what that means, this page explains the disease, the recent name change, and why so many metabolic molecules target it.
Key Takeaways
- MASH stands for metabolic dysfunction-associated steatohepatitis, a fatty liver disease with inflammation and liver-cell injury.
- MASH is the newer name for what used to be called NASH.
- MASLD (formerly NAFLD) is the broader category of fat in the liver; MASH is a more serious form within it.
- Untreated MASH can progress to fibrosis (scarring) and, in some cases, cirrhosis.
- GLP-1, GLP-1/glucagon, and triple agonist drugs are heavily studied for MASH.
- This page is educational background and is not medical advice, diagnosis, or treatment guidance.
1. What Is MASH?
MASH stands for metabolic dysfunction-associated steatohepatitis. It is a form of fatty liver disease in which excess fat in the liver is accompanied by inflammation and liver-cell injury. The “steato” part refers to fat, and “hepatitis” refers to liver inflammation.
MASH is more serious than simply having fat in the liver. The added inflammation and cell damage are what can, over time, drive scarring of the liver tissue.
| Term | What it means |
|---|---|
| MASH | Metabolic dysfunction-associated steatohepatitis: fat + inflammation + cell injury. |
| MASLD | The broader category of fat in the liver (formerly NAFLD). |
| Steatosis | Fat accumulation in the liver. |
| Fibrosis | Scarring of the liver, which MASH can lead to. |
2. The 2023 Name Change: NASH to MASH
If you have read older material, you may know this disease as NASH (nonalcoholic steatohepatitis). In 2023, a multi-society group of liver organizations updated the terminology. The goals were to describe the condition by its link to metabolic health rather than by what it is not (“nonalcoholic”), and to reduce stigma.
| Old name | New name |
|---|---|
| NAFLD (nonalcoholic fatty liver disease) | MASLD (metabolic dysfunction-associated steatotic liver disease) |
| NASH (nonalcoholic steatohepatitis) | MASH (metabolic dysfunction-associated steatohepatitis) |
So MASH and NASH refer to the same disease; the label was modernized.
3. MASLD vs MASH vs Fibrosis
These terms describe a spectrum, from mild to more advanced.
- MASLD: the umbrella term for fat building up in the liver. Many people have this with no symptoms.
- MASH: a more advanced form within MASLD, where inflammation and liver-cell injury are also present.
- Fibrosis: scarring of liver tissue that MASH can cause over time. Severe, advanced scarring is called cirrhosis.
Disease progression varies a great deal between individuals, and not everyone with fat in the liver develops MASH.
4. Why GLP-1 Drugs Are Studied for MASH
MASH is tightly linked to weight and metabolic health, which is exactly what incretin-based drugs act on. Two mechanisms make these molecules attractive candidates in MASH research:
5. Which Drugs Are Studied in MASH
Many molecules in the broader GLP-1 family run MASH trials. Some are primarily obesity drugs being tested in the liver; others treat MASH as their lead program.
| Drug | Mechanism | MASH role |
|---|---|---|
| Pemvidutide | GLP-1/glucagon | MASH is a lead program |
| Survodutide | GLP-1/glucagon | Phase 3 in MASH |
| Efinopegdutide | GLP-1/glucagon | Liver-focused program |
| Retatrutide | GIP/GLP-1/glucagon | Studied across metabolic conditions including the liver |
The presence of a glucagon component in most of these is not a coincidence; it is the design feature aimed at the liver.
6. Where MASH Fits
MASH is the liver-disease anchor of the modern metabolic drug story. Understanding it explains why so many GLP-1 molecules, especially the ones that add glucagon, are tested far beyond weight and diabetes.
- MASH = fat plus inflammation plus liver-cell injury.
- Formerly NASH, renamed in 2023.
- Part of MASLD, the broader fatty-liver category.
- Targeted by GLP-1/glucagon and triple agonist drugs because of the weight-plus-liver mechanism.
7. What Is MASH FAQ
What is MASH in simple terms?
MASH is a liver disease in which excess fat in the liver is accompanied by inflammation and liver-cell damage. The full name is metabolic dysfunction-associated steatohepatitis. It is a more serious stage than simply having fat in the liver.
What is the difference between MASH and NASH?
They refer to the same disease. In 2023, medical organizations updated the terminology, replacing NASH (nonalcoholic steatohepatitis) with MASH (metabolic dysfunction-associated steatohepatitis) to better describe its link to metabolic health and to avoid defining it by what it is not.
How are MASLD and MASH related?
MASLD (metabolic dysfunction-associated steatotic liver disease, formerly NAFLD) is the umbrella term for fat buildup in the liver. MASH is a more advanced form within MASLD where inflammation and cell injury are also present.
Why are GLP-1 drugs studied for MASH?
MASH is closely tied to weight and metabolic health. GLP-1 drugs reduce weight and improve metabolic markers, and adding a glucagon receptor target can directly reduce liver fat. That is why many GLP-1, GLP-1/glucagon, and triple agonist molecules are tested in MASH trials. This is not a statement that any specific drug treats MASH.
Is MASH the same as cirrhosis?
No. MASH can progress to fibrosis (scarring) and, in some people, eventually to cirrhosis (severe, advanced scarring), but MASH itself is an earlier stage. Disease progression varies widely between individuals.