Acute liver failure is loss of liver function that happens quickly — in days or weeks — usually in a person who has no preexisting liver disease. It's most often caused by a hepatitis virus or drugs, such as acetaminophen. Acute liver failure is less common than chronic liver failure, which develops more slowly.

Acute liver failure, also known as fulminant hepatic failure, can cause serious complications, including bleeding and increased pressure in the brain. It's a medical emergency that requires hospitalization.

Depending on the cause, acute liver failure can sometimes be reversed with treatment. In many situations, though, a liver transplant may be the only cure.

Symptoms of acute liver failure may include:

• Yellowing of the skin and eyeballs, called jaundice.
• Pain in the upper right belly area, called the abdomen.
• A swollen belly, known as ascites.
• Nausea and vomiting.
• A general sense of feeling unwell, known as malaise.
• Disorientation or confusion.
• Sleepiness.
• Breath with a musty or sweet odor.
• Tremors.

When to see a doctor

Acute liver failure can develop quickly in an otherwise healthy person, and it is life-threatening. If you or someone you know suddenly develops a yellowing of the eyes or skin; tenderness in the upper belly; or any unusual changes in mental state, personality or behavior, seek medical attention right away.

Risk factors for acute liver failure include:

• Being female. A majority of people affected by acute liver failure are female.
• Underlying illness. Many conditions, including viral hepatitis, metabolic disease, autoimmune disease and cancer can increase the risk of acute liver failure.

Acute liver failure occurs when liver cells are seriously damaged and are no longer able to function. Possible causes include:

• Acetaminophen overdose. Taking too much acetaminophen (Tylenol, others) is the most common cause of acute liver failure in the United States. Outside of the United States, acetaminophen is known as paracetamol. Acute liver failure can happen after one very large dose of acetaminophen, or after higher than recommended doses every day for several days.

  If you or someone you know has taken an overdose of acetaminophen, seek medical attention as quickly as possible. Treatment may prevent liver failure. Don't wait for the symptoms of liver failure.

• Hepatitis and other viruses. Hepatitis A, hepatitis B and hepatitis E increase the risk of acute liver failure. Other viruses that can increase risk include Epstein-Barr virus, cytomegalovirus and herpes simplex virus.
• Prescription medicines. Some prescription medicines, including antibiotics, nonsteroidal anti-inflammatory drugs and anticonvulsants, can cause acute liver failure.
• Herbal supplements. Herbal drugs and supplements, including kava, ephedra, skullcap and pennyroyal, have been linked to acute liver failure.
• Toxins. Toxins that can cause acute liver failure include the poisonous wild mushroom Amanita phalloides, which is sometimes mistaken for one that is safe to eat. Carbon tetrachloride is another toxin that can cause acute liver failure. It is an industrial chemical found in refrigerants and solvents for waxes, varnishes and other materials.
• Autoimmune disease. Liver failure can be caused by autoimmune hepatitis — a disease in which the immune system attacks liver cells, causing inflammation and injury.
• Diseases of the veins in the liver. Vascular diseases, such as Budd-Chiari syndrome, can cause blockages in the veins of the liver and lead to acute liver failure.
• Metabolic disease. Rare metabolic diseases, such as Wilson's disease and acute fatty liver of pregnancy, sometimes cause acute liver failure.
• Cancer. Cancer that either begins in or spreads to the liver can cause the liver to fail.
• Shock. Overwhelming infection, called sepsis, and shock can severely reduce blood flow to the liver, causing liver failure.
• Heat stroke. Extreme physical activity in a hot environment can trigger acute liver failure.

Some cases of acute liver failure have no obvious cause.

Acute liver failure often causes complications, including:

• Too much fluid in the brain, called cerebral edema. Too much fluid causes pressure to build up in the brain, which can lead to disorientation, severe mental confusion and seizures.
• Bleeding and bleeding disorders. A failing liver cannot make enough clotting factors, which help blood to clot. Bleeding in the gastrointestinal tract is common with this condition. It may be difficult to control.
• Infections. People with acute liver failure are more likely to develop infections, particularly in the blood and in the respiratory and urinary tracts.
• Kidney failure. Kidney failure often occurs after liver failure, especially with an acetaminophen overdose, which damages both the liver and the kidneys.

Reduce your risk of acute liver failure by taking care of your liver.

• Follow instructions on medicines. If you take acetaminophen or other medicines, check the package insert for the recommended dose, and don't take more than that. If you already have liver disease, ask your healthcare team if it is safe to take any amount of acetaminophen.
• Tell your healthcare team about all your medicines. Even nonprescription and herbal medicines can interact with prescription drugs you're taking.
• Drink alcohol in moderation, if at all. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men.
• Avoid risky behavior. Get help if you use illicit intravenous drugs. Don't share needles. Use condoms during sex. If you get tattoos or body piercings, make sure the shop you choose is clean and safe. Don't smoke.
• Get vaccinated. If you have chronic liver disease, a history of any type of hepatitis infection or an increased risk of hepatitis, talk to your care team about getting the hepatitis B vaccine. A vaccine also is available for hepatitis A.
• Be careful not to come into contact with other people's blood and body fluids. Accidental needle sticks or improper cleanup of blood or body fluids can spread hepatitis viruses. Sharing razor blades or toothbrushes also can spread infection.
• Don't eat wild mushrooms. It can be difficult to tell the difference between a poisonous mushroom and one that is safe to eat.
• Take care with aerosol sprays. When you use an aerosol cleaner, make sure the room is ventilated, or wear a mask. Take similar protective measures when spraying insecticides, fungicides, paint and other toxic chemicals. Follow product instructions carefully.
• Watch what gets on your skin. When using insecticides and other toxic chemicals, cover your skin with gloves, long sleeves, a hat and a mask.
• Maintain a healthy weight. Obesity can cause a condition called nonalcoholic fatty liver disease (NAFLD), now called metabolic dysfunction-associated steatotic liver disease (MASLD). MASLD may lead to serious liver damage.

Tests and procedures used to diagnose acute liver failure include:

• Blood tests. Blood tests can show how well the liver works. A prothrombin time test measures how long it takes blood to clot. With acute liver failure, blood doesn't clot as quickly as it should.
• Imaging tests. A healthcare professional may recommend an ultrasound exam to look at the liver. Such testing may show liver damage and help find the cause of the liver problems. A health professional also may recommend abdominal computerized tomography (CT) scanning or magnetic resonance imaging (MRI) to look at the liver and blood vessels. These tests can look for certain causes of acute liver failure, such as Budd-Chiari syndrome or tumors. They may be used if a problem is suspected and ultrasound testing does not find the problem.

• Examination of liver tissue. A healthcare professional may recommend removing a small piece of liver tissue, called a liver biopsy. Doing so may help discover why the liver is failing.

  Since people with acute liver failure are at risk of bleeding during biopsy, a transjugular liver biopsy may be performed. This procedure involves making a tiny incision on the right side of the neck. A thin tube called a catheter is then inserted into a neck vein, through the heart and into a vein exiting the liver. A needle is then threaded through the catheter to retrieve a sample of liver tissue.

People with acute liver failure often receive treatment in the intensive care unit of a hospital in a facility that can perform a liver transplant, if necessary. A healthcare professional may try to treat the liver damage itself, but in many cases, treatment involves controlling complications and giving the liver time to heal.

Acute liver failure treatments may include:

• Medicines to reverse poisoning. Acute liver failure caused by acetaminophen overdose is treated with a medicine called acetylcysteine. This medicine also may help treat other causes of acute liver failure. Mushroom and other poisonings also may be treated with medicines that can reverse the effects of the toxin and may reduce liver damage.
• Liver transplant. When acute liver failure can't be reversed, the only treatment may be a liver transplant. During a liver transplant, a surgeon removes the damaged liver and replaces it with a healthy liver from a donor.

A healthcare professional also will typically work to control symptoms and try to prevent complications caused by acute liver failure. Care may include:

• Relieving pressure caused by excess fluid in the brain. Cerebral edema caused by acute liver failure can increase pressure on the brain. Medicines can help reduce the fluid buildup in your brain.
• Screening for infections. Your medical team may take samples of your blood and urine every now and then to be tested for infection. If your team suspects that you have an infection, you'll receive medicines to treat the infection.
• Preventing severe bleeding. Your care team can give you medicines to reduce the risk of bleeding. If you lose a lot of blood, tests may be done to find the source of the blood loss. Blood transfusions may be needed.
• Providing nutritional support. If you're not able to eat, you may need supplements to treat nutritional deficiencies.

Future treatments

Scientists continue to research new treatments for acute liver failure, especially those that could reduce or delay the need for a liver transplant. While several possible future treatments are being explored, it's important to remember that the treatments are experimental and may not yet be available.

These treatments are among those being studied:

• Artificial hepatic assist devices. A machine would do the job of the liver, much like dialysis helps when the kidneys stop working. There are many different types of devices being studied. Research suggests that some, but not all, devices may improve survival. A well-controlled multicenter trial showed that one system, called an extracorporeal liver support system, helped some people with acute liver failure survive without a transplant. The treatment also is called high-volume plasma exchange. However, more study is needed for this therapy.
• Hepatocyte transplantation. Transplanting only the cells of the liver — not the entire organ — may temporarily delay the need for a liver transplant. In some cases, a short-term delay could lead to a complete recovery. A shortage of good-quality donor livers has limited the use of this treatment.
• Auxiliary liver transplantation. This procedure involves removing a small piece of your liver and replacing it with a similarly sized graft. This allows your own liver to regenerate without the need for immunosuppressant drugs. At this time, auxiliary liver transplantation is a difficult procedure that needs more research.
• Xenotransplantation. This type of transplant replaces the human liver with a liver from an animal or other nonhuman source. Doctors performed experimental liver transplants using pig livers several decades ago, but results were disappointing. However, advancements in immune and transplant medicine have prompted researchers to consider this treatment again. It may help provide support for those waiting for a human liver transplant.

If a healthcare professional suspects you have acute liver failure, you'll likely be admitted to a hospital for treatment. Most people with acute liver failure are treated in an intensive care unit.

What you can do

If you have been diagnosed with acute liver failure, here are some questions to ask your care team:

• What caused my acute liver failure?
• Can it be reversed?
• If it can be reversed, can my liver completely heal?
• What are the treatments?
• Will I need a liver transplant?
• Does this hospital have a liver transplant unit?
• Should I transfer to a hospital that performs liver transplants?

What to expect from your doctor

Your care team will ask you or your family questions to try to find the cause of your acute liver failure, including:

• When did symptoms begin?
• What prescription medicines do you take?
• What over-the-counter medicines do you take?
• What herbal supplements do you take?
• Do you use illegal drugs?
• Have you had liver problems in the past?
• Have you been diagnosed with hepatitis or jaundice?
• Do you have a history of depression or suicidal thoughts?
• How much alcohol do you drink?
• Have you recently started taking new medicines?
• Do you take acetaminophen (Tylenol, others)? How much?
• Do liver problems run in your family?