What Causes Liver Damage?

There are many types of liver diseases, including the following:

• Cirrhosis: Occurs when the liver is scarred and permanently damaged as scar tissue replaces healthy tissue and prevents the liver from working normally.
• Autoimmune hepatitis: A chronic disease in which the immune system attacks the liver, causing inflammation and damage. Without treatment, it can lead to cirrhosis.
• Nonalcoholic fatty liver disease (NAFLD): Occurs when fat builds up in the liver. NAFLD typically does not progress to cause liver damage, but it can cause pain. When inflammation and liver damage are present, this condition is called nonalcoholic steatohepatitis (NASH). NASH can lead to cirrhosis.
• Hemochromatosis: A condition in which iron builds up in the body, damaging the liver, among other organs. The most common type of hemochromatosis is genetic in nature.
• Hepatitis B and C: Liver infections that can be short-term or chronic, causing inflammation and damage. Most cases can last up to six months in the acute stage. Chronic hepatitis B or C can lead to cirrhosis, liver failure, or liver cancer.

Liver disease has many causes. Infections, such as parasites or viruses, can cause inflammation in the liver and cause hepatitis A, B, or C. Autoimmune diseases can cause autoimmune hepatitis, primary sclerosing cholangitis, or primary biliary cholangitis. There are also several genetic diseases that can cause certain substances to build up and damage the liver, including hemochromatosis and alpha-1 antitrypsin deficiency. Other common causes of liver disease include chronic alcohol use, some prescription or over-the-counter medications, and certain herbal compounds.

Catching liver disease early can be crucial to treatment. Unfortunately, many forms of liver disease do not have any symptoms until the disease has already caused cirrhosis. Early symptoms of cirrhosis may include feeling weak or tired, having itchy skin, and losing weight without trying. Other signs can be poor appetite, nausea and vomiting, muscle cramps, sexual dysfunction, or mild pain or discomfort over the right upper abdomen.

Chronic liver injury can lead to inflammation and scarring. As this progresses to cirrhosis, it can cause the collapse of liver structures, formation of nodules, and disruption of blood flow. Any liver damage from any cause can result in cirrhosis, but there is an increased risk in people with comorbidities (particularly hepatitis C and HIV), advanced age, or males, except in the case of alcoholic liver disease, when females progress more quickly. Researchers are unsure of the point where cirrhosis becomes irreversible. Patients with cirrhosis can remain stable or compensated for years, and the variability of progression depends on the underlying cause, treatment, and any continuing liver injury.

Excessive alcohol consumption can affect liver function and contribute to three types of liver disease: alcoholic fatty liver, alcoholic hepatitis, or alcohol-related cirrhosis. Fatty liver is the earliest stage of alcohol-related liver disease. It is usually reversible if the person stops drinking, but most people do not have symptoms, so it can be challenging to catch it early. Alcoholic hepatitis causes the liver to swell and destroys liver cells. The mild form can last for years if the person keeps drinking. Severe, life-threatening cases can occur suddenly, usually after a period of binge drinking. As many as 20 percent of people with ten or more years of heavy drinking develop cirrhosis.

There are five viruses that cause viral hepatitis, an inflammation of the liver. The three most common are hepatitis A, B, and C. Hepatitis A is relatively mild and the least likely to cause liver damage. Most cases resolve in six months. This form of viral hepatitis can be spread through contaminated water and unwashed food. Hepatitis B is a chronic disorder that can lead to long-term liver damage, cirrhosis, and liver cancer over time. It can be transmitted via exposure to contaminated needles or syringes, contaminated blood or body fluids, and from mother to child during childbirth. Hepatitis C is only transmitted through infected blood or from mother to baby during birth and can also lead to cirrhosis or liver cancer.

Nonalcoholic fatty liver disease (NAFLD) occurs when people have fat inside their liver unrelated to alcohol consumption. Over time, this can lead to liver damage or impaired live functioning. There are two types of NAFLD. If you have fat in your liver but no liver damage, it is called NAFLD. If you have signs of liver damage, it is called nonalcoholic steatohepatitis (NASH). NAFLD is the most common form of liver disease in the U.S., affecting as much as 30 percent of adults.

The two most common liver diseases caused by genetics are hemochromatosis and alpha-1 antitrypsin deficiency. Hemochromatosis is a disease in which you absorb more iron than you need. The body cannot get rid of this iron, so it stores it in the tissues, which can lead to organ failure if untreated. Alpha-1 antitrypsin deficiency (AATD) is a rare disorder that causes low levels of AAT. AAT is a protein made in the liver that helps the lungs work normally. AATD primarily damages the lungs, but about 10 percent of infants with AATD develop liver disease and about 15 percent of adults with AATD develop cirrhosis due to formation of scar tissue in the liver.

Many drug classes can cause liver damage, including nonsteroidal anti-inflammatory drugs (NSAIDs), anti-cancer drugs, and immunosuppressants. Acetaminophen is the most common cause of drug-induced liver damage. Dietary supplements can also cause toxicity, with some research indicating that between two and 16 percent of all cases of liver toxicity in wasted countries are the result of herbal and dietary substances.

Metabolic conditions, like obesity and diabetes, can lead to metabolic dysfunction–associated liver disease (MASLD). This condition starts as fatty infiltrations but can advance to inflammation, fibrosis, and scarring. When liver damage is present, this condition is called metabolic dysfunction–associated steatohepatitis (MASH). What causes metabolic-related liver damage is not fully understood, but it may be linked to insulin resistance.

Many liver diseases do not have symptoms until they are advanced, so identifying symptoms of progressing liver disease is crucial to ensure timely treatment. Some signs of advanced liver disease include jaundice (yellowing of the skin and eyes), loss of appetite, and feeling weak or tired. People with advanced liver disease may bruise and bleed easily, and they may develop ascites, which is a collection of fluid in the abdomen. In severe cases, brain function may begin to deteriorate as the liver is no longer able to remove toxic substances, allowing them to build up in the blood.

Doctors can use a range of blood tests to evaluate liver health. Serum bilirubin tests measure the amount of bilirubin in the blood. Bilirubin is made by the liver and is a part of bile, and elevated levels may mean there is an obstruction or that the liver is not processing bile properly. Serum albumin tests measure the amount of the protein albumin; low levels may indicate the liver is not functioning as it should be. There are also tests that measure the level of various liver enzymes, including alkaline phosphatase, alanine transaminase, and aspartate transaminase. Anything outside of the normal range can indicate problems in the liver.

Treatment and management strategies for liver disease depend on the cause. For cirrhosis, doctors might prescribe medication to prevent further damage and often recommend lifestyle changes, like losing weight, stopping any medications that are causing damage, or completely stopping alcohol use. Antiviral drugs may be used to treat hepatitis B or C, while autoimmune hepatitis may be managed with medications that suppress the immune system.

To help prevent liver disease, drink alcohol in moderation, up to one drink a day for women or two for men. Avoid risky behavior, like having unprotected sex or sharing needles. Use medications carefully, only when needed, and in the recommended doses. Do not mix drugs and alcohol, and talk to your doctor before taking any herbal supplements. Keep your food safe, wash your hands before preparing or eating food, and use bottled water to drink, wash your hands, and brush your teeth when traveling in other countries.

If you are living with liver disease, there are ways to keep it from getting worse. Avoid alcohol and illegal drug use. Talk to your doctor before taking any medications, including over-the-counter pain relievers like NSAIDs and acetaminophen, and take any prescribed medications as directed. Do not take dietary supplements, including herbal supplements, and get vaccinated against hepatitis A, hepatitis B, pneumonia, flu, and shingles, and get screened for hepatitis C. Try to maintain a healthy body weight and eat healthy foods and drinks.