Liver Disease

What the liver does

The liver is the largest internal organ, sitting under the right lower ribs. It:

• processes nutrients and stores energy as glycogen
• makes proteins, including albumin and clotting factors
• produces bile to digest fats
• clears toxins, drugs and alcohol
• regulates cholesterol and blood sugar

The liver can regenerate, which is why early damage often reverses. Repeated injury leads to scarring (fibrosis) and eventually cirrhosis.

Stages of liver damage

1. Inflammation or fat buildup: often reversible.
2. Fibrosis: scar tissue starts to form; still largely reversible if the cause is removed.
3. Cirrhosis: extensive scarring that distorts the liver structure. Compensated cirrhosis may cause few symptoms; decompensated cirrhosis causes ascites, jaundice, bleeding and confusion.
4. Liver failure: the liver can no longer perform its functions.

Common types of liver disease

Fatty liver disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly called NAFLD, is the most common liver disease, affecting roughly a third of adults. It is linked to obesity, type 2 diabetes, high blood pressure and high cholesterol. The inflammatory form, MASH (formerly NASH), can progress to cirrhosis. See nonalcoholic liver disease.

Alcohol-related liver disease

Heavy drinking causes fatty liver, alcoholic hepatitis and cirrhosis. Risk rises with the amount and duration of drinking. See alcoholic liver disease.

Viral hepatitis

• Hepatitis B: spread through blood, sex and from mother to baby. Chronic infection can cause cirrhosis and liver cancer. Preventable by vaccine; controlled with antivirals.
• Hepatitis C: spread mainly through blood. Curable in over 95 percent of people with 8 to 12 weeks of antiviral tablets.
• Hepatitis A and E: usually short-lived infections from contaminated food or water.

Other causes

• autoimmune hepatitis: the immune system attacks the liver
• primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC): diseases of the bile ducts
• hemochromatosis: inherited iron overload
• Wilson disease: inherited copper buildup
• alpha-1 antitrypsin deficiency
• drug-induced liver injury: acetaminophen overdose, some antibiotics, and herbal and bodybuilding supplements
• liver cancer: usually in people with cirrhosis or chronic hepatitis B

Symptoms

Early liver disease is often silent. When symptoms appear, they include:

• fatigue and weakness
• loss of appetite, nausea and weight loss
• discomfort under the right ribs
• jaundice: yellow skin and eyes
• dark urine and pale stools
• itchy skin
• easy bruising and bleeding
• swelling of the belly (ascites) and legs
• spider-like blood vessels on the skin, red palms
• confusion, sleep changes or drowsiness (hepatic encephalopathy)
• vomiting blood or black stools from enlarged veins (varices)

Risk factors

• drinking more than recommended limits
• obesity, type 2 diabetes and metabolic syndrome
• injecting drugs, unsafe tattoos, blood transfusions before 1992
• unprotected sex and multiple partners
• being born in regions with high hepatitis B rates
• family history of liver disease
• exposure to some medicines, supplements and toxins

Diagnosis

• Liver blood tests: ALT, AST, alkaline phosphatase, GGT, bilirubin, albumin and INR.
• Hepatitis B and C tests: the CDC recommends hepatitis C testing for all adults at least once, and hepatitis B screening for all adults.
• Other blood tests: iron studies, autoimmune antibodies, ceruloplasmin, alpha-1 antitrypsin.
• Ultrasound: shows fat, liver size, cirrhosis and tumors.
• Fibrosis assessment: blood scores such as FIB-4 and elastography (FibroScan), which measures liver stiffness.
• Liver biopsy in selected cases.

Treatment

• Fatty liver: weight loss of 7 to 10 percent can reduce fat, inflammation and fibrosis; manage diabetes, blood pressure and cholesterol. Resmetirom is FDA-approved for MASH with moderate to advanced fibrosis, and semaglutide (a GLP-1 medicine) was approved for the same use in 2025.
• Alcohol-related: stopping alcohol completely is the most important treatment, with support and medicines for alcohol use disorder.
• Hepatitis B: long-term antivirals when indicated.
• Hepatitis C: curative direct-acting antivirals.
• Autoimmune and bile duct diseases: immunosuppressants, ursodiol and other specific medicines.
• Hemochromatosis: regular blood removal (venesection).
• Cirrhosis care: screening for liver cancer every 6 months, endoscopy for varices, diuretics for fluid, lactulose for confusion, vaccinations, and nutrition.
• Liver transplant: for end-stage liver disease or some liver cancers.

Protecting your liver

• keep alcohol within limits or avoid it
• maintain a healthy weight and stay active
• get vaccinated against hepatitis A and B
• get tested for hepatitis C
• do not exceed the label dose of acetaminophen (paracetamol), and be careful with combination cold and flu products that also contain it
• be cautious with herbal and bodybuilding supplements

Frequently asked questions

What are the early signs of liver disease?

Early liver disease often has no symptoms. When present, early signs are tiredness, loss of appetite, nausea and discomfort under the right ribs. Abnormal liver blood tests on a routine check are often the first clue.

What is the most common cause of liver disease?

Fatty liver disease linked to obesity, diabetes and metabolic syndrome (MASLD) is now the most common cause. Alcohol and viral hepatitis B and C are other major causes.

Can the liver repair itself?

Yes, to a large degree. The liver can regenerate, and fatty liver, inflammation and early fibrosis often improve when the cause is removed. Advanced cirrhosis is usually not reversible, but stopping the cause can prevent further damage.

What are the signs that liver disease is getting worse?

Worsening signs include jaundice, a swelling belly, leg swelling, easy bruising, confusion or drowsiness, and vomiting blood or black stools. These indicate decompensated cirrhosis and need urgent medical care.

How is liver disease diagnosed?

Doctors use liver blood tests, hepatitis tests, ultrasound and tests of liver stiffness such as FibroScan or blood-based fibrosis scores. A liver biopsy is sometimes needed to confirm the cause or stage.