The largest organ inside your body is your liver. It sits on the right side of your abdomen, just below your diaphragm. The liver weighs about 3 pounds in an adult and performs more than 500 vital jobs, from filtering blood to processing nutrients.
What Is The Largest Organ Inside Your Body? Definition
The liver is the largest solid internal organ. It is also the largest gland. The skin is the largest organ overall, but it is external. When people ask about the largest organ inside the body, the answer is always the liver.
The liver is roughly the size of a football. It is wedge-shaped and has two main lobes. It is reddish-brown and holds about 13 percent of your total blood supply at any given moment. That blood flow is central to everything the liver does.
What Does the Liver Actually Do?
The liver is the body’s main chemical processing plant. Almost everything you eat, drink, or absorb through your skin eventually passes through it. The liver decides what to store, what to use, and what to remove.
One of its most important jobs is filtering blood. Blood comes to the liver from the digestive tract through the portal vein. The liver removes bacteria, old red blood cells, and toxins before the blood moves on to the rest of the body.
The liver also processes nutrients. It converts carbohydrates into glucose for energy and stores the excess as glycogen. It breaks down fats and proteins. It makes bile, a fluid that helps you digest fat in the small intestine.
Beyond digestion, the liver produces essential proteins. It makes albumin, which keeps fluid in your blood vessels. It makes clotting factors that stop bleeding when you are injured. Without these proteins, your body cannot function normally.
How the Liver Regenerates
The liver is the only internal organ that can regrow lost tissue. If a surgeon removes up to 70 percent of a healthy liver, it can grow back to full size within weeks or months. This is why living-donor liver transplants are possible.
Regeneration is not unlimited. It works well when the remaining liver tissue is healthy. If the liver is damaged by cirrhosis or chronic disease, regeneration is impaired. The scar tissue that forms in cirrhosis does not regrow into healthy liver cells.
This regenerative ability is one reason the liver can tolerate years of moderate damage before symptoms appear. By the time symptoms develop, significant damage may already be present.
Common Liver Conditions You Should Know
Several conditions can damage the liver. The most common in the United States is fatty liver disease. This occurs when fat builds up in liver cells. It is strongly linked to obesity, type 2 diabetes, and high alcohol intake.
Fatty liver disease often has no symptoms in its early stages. Some people feel fatigue or mild discomfort in the upper right abdomen. Many people only learn they have it after routine blood tests show elevated liver enzymes.
Viral hepatitis is another major cause of liver damage. Hepatitis A, B, and C are different viruses that affect the liver in different ways. Hepatitis B and C can become chronic and lead to cirrhosis or liver cancer over time. Vaccines exist for hepatitis A and B. Hepatitis C can now be cured in most cases with antiviral medication.
Cirrhosis is the end stage of many liver diseases. It happens when healthy liver tissue is replaced by scar tissue. This scar tissue blocks blood flow and prevents the liver from working properly. Cirrhosis is not reversible, but treatment can slow its progression.
Signs Your Liver May Need Attention
Liver disease is often called silent because early symptoms are vague or absent. When symptoms do appear, they can include jaundice, which is yellowing of the skin and eyes. Dark urine and pale stool can also signal liver problems.
Other signs include persistent fatigue, nausea, loss of appetite, and unexplained weight loss. Swelling in the legs or abdomen can occur when the liver fails to produce enough albumin. Easy bruising or bleeding may indicate the liver is not making enough clotting factors.
These symptoms are not specific to liver disease. Many other conditions cause them. But if you have several of these symptoms together, especially with risk factors like heavy alcohol use or obesity, you should talk to a doctor.
Blood tests can check liver health. The most common are liver enzyme tests, which measure ALT and AST. Elevated levels suggest liver cell damage. Other tests check bilirubin, albumin, and clotting time. Imaging tests like ultrasound can show fat, scar tissue, or tumors.
How to Protect Your Liver
Liver health largely comes down to lifestyle choices. Limiting alcohol is the single most important step for many people. Moderate drinking is defined as up to one drink per day for women and up to two for men. Heavy drinking over years is a direct cause of liver damage.
Maintaining a healthy weight matters. Obesity is the leading risk factor for fatty liver disease. Even a 5 to 10 percent weight loss can reduce liver fat and inflammation in people with fatty liver.
Vaccination protects against hepatitis A and B. Practicing safe sex and avoiding shared needles reduces the risk of hepatitis B and C. Getting tested if you have risk factors is important because treatment works best before significant damage occurs.
Be cautious with medications and supplements. Acetaminophen is safe at recommended doses but can cause severe liver damage in overdose. Some herbal supplements, including certain weight-loss and bodybuilding products, have been linked to liver injury. Always tell your doctor about every supplement you take.
What Happens When the Liver Fails?
Liver failure is a medical emergency. Acute liver failure can develop in days, often from medication overdose or viral infection. Chronic liver failure develops slowly over years as cirrhosis progresses.
When the liver fails, toxins build up in the blood. This can cause confusion, disorientation, and coma, a condition called hepatic encephalopathy. Fluid accumulates in the abdomen. Bleeding can occur in the esophagus from swollen veins. Kidney function often declines.
Treatment depends on the cause and severity. Some causes are reversible if caught early. For advanced failure, a liver transplant may be the only option. More than 9,000 liver transplants are performed in the United States each year, with good long-term outcomes.
Frequently Asked Questions
Is the liver the largest organ in the human body?
No, the skin is the largest organ overall. The liver is the largest internal organ and the largest solid organ inside the body.
How big is the human liver?
An adult liver weighs about 3 pounds and is roughly the size of a football. It measures about 10 to 12 inches across at its widest point.
Can the liver repair itself?
Yes, the liver can regenerate damaged tissue if the remaining tissue is healthy. This ability is limited when cirrhosis or chronic disease is present.
What are early signs of liver damage?
Early liver damage often has no symptoms at all. When symptoms appear, they may include fatigue, nausea, loss of appetite, and mild pain in the upper right abdomen.
