Acute Liver Failure Criteria: How Doctors Diagnose and What You Should Know
Acute liver failure (ALF) is a rare but life-threatening emergency. It happens when your liver suddenly stops working — usually in someone without prior liver disease. It can develop in days or weeks. Fast diagnosis and treatment can save lives.
This article explains the clinical criteria for ALF, common symptoms, how it's tested, and what treatment may involve. It’s written to help you or your loved ones understand this condition in plain language.
What is acute liver failure?
Acute liver failure means your liver stops functioning quickly. The liver normally helps your body by:
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Filtering toxins from your blood
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Producing proteins (like those that help your blood clot)
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Storing energy and nutrients
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Processing medications
When the liver fails, toxins build up, bleeding risks increase, and other organs may be affected.
For more insight into how toxins and infections can silently damage the liver, read about early detection of liver disease.
What are the diagnostic criteria for acute liver failure?
Doctors typically use three key criteria to define ALF:
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Evidence of liver injury: This is seen as a sharp rise in liver enzymes (ALT or AST) in blood tests.
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Hepatic encephalopathy: This means confusion, personality changes, extreme fatigue, or even coma due to toxin buildup in the brain.
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Impaired blood clotting: Measured using the INR (International Normalized Ratio), which should be ≥ 1.5 in ALF cases.
These features must occur in someone with no known chronic liver disease.
How do symptoms of acute liver failure start?
ALF can start suddenly and may seem like a general illness at first. Watch for:
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Nausea, vomiting, or feeling unwell
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Yellowing of the skin or eyes (jaundice)
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Sleepiness, confusion, or irritability
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Bleeding easily or unexplained bruises
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Swollen belly or legs
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Breath that smells sweet or like ammonia
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Personality or mood changes
These symptoms can worsen quickly. If you or someone near you experiences these signs, go to the emergency room.
What causes acute liver failure?
ALF has many possible causes, but some of the most common include:
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Acetaminophen (Tylenol) overdose: Even short-term high doses can cause liver failure.
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Viral hepatitis: Hepatitis A, B, or E infections can damage the liver.
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Drug reactions: Certain antibiotics, anti-seizure meds, and herbal products may be toxic to the liver.
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Autoimmune hepatitis: The immune system mistakenly attacks the liver.
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Wilson’s disease: A rare genetic disorder that causes copper buildup.
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Toxins: Such as poisonous mushrooms or chemicals.
In some cases, no clear cause is found.
How do doctors test for acute liver failure?
Doctors use several tests to diagnose ALF:
Blood tests:
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Liver enzymes (ALT, AST): Show liver cell damage
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INR: Measures blood clotting ability
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Bilirubin: Elevated in liver dysfunction
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Ammonia levels: Higher levels can cause brain symptoms
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Kidney function: Since liver failure can affect other organs
Imaging:
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Ultrasound or CT scan: To look at liver size, structure, and blood flow
Neurological exam:
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Checks for signs of encephalopathy (mental confusion, sleepiness, etc.)
Additional tests:
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For viral hepatitis, autoimmune antibodies, drug levels, and rare conditions like Wilson’s disease
Why is early treatment important?
ALF can lead to serious complications within hours or days:
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Brain swelling (cerebral edema)
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Internal bleeding
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Kidney failure
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Infections
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Multi-organ failure
Early intervention improves your chances of survival. Some people recover fully with supportive care. Others may need a liver transplant urgently.
Learn how to assess your liver from home with our guide to the Ribbon Liver Test.
What is the treatment for acute liver failure?
Treatment depends on the cause, severity, and timing.
Hospital care:
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Most patients are admitted to an intensive care unit (ICU)
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IV fluids and medications to support blood pressure and reduce brain swelling
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Frequent monitoring of blood tests, breathing, and brain activity
Targeted treatments:
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Acetaminophen overdose: Treated with a medication called N-acetylcysteine (NAC)
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Infections: Treated with antivirals or antibiotics
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Autoimmune causes: May be treated with corticosteroids
Liver transplant:
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This is often needed when liver damage is severe and irreversible
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The transplant team will evaluate whether someone qualifies quickly
Not all patients are transplant candidates. Doctors use scoring systems (like the King’s College Criteria) to decide.
To understand how long you can live with liver failure and what outcomes to expect, read our article on how long can you live with liver failure.
Can acute liver failure be prevented?
Yes — some causes of ALF are avoidable. Here's what you can do:
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Take medications only as directed (especially acetaminophen)
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Don’t mix alcohol with medications
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Avoid unknown or wild mushrooms
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Get vaccinated for hepatitis A and B
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Avoid sharing needles or personal items that carry hepatitis risk
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Get regular checkups if you have liver concerns or chronic conditions
What’s the difference between acute and chronic liver failure?
Acute liver failure happens quickly in people who usually had no liver disease before.
Chronic liver failure happens over months or years, often due to long-term damage from:
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Alcohol
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Hepatitis B or C
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Fatty liver disease
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Autoimmune or inherited conditions
What’s the outlook for someone with ALF?
Outcomes depend on:
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How early treatment starts
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Whether the cause is treatable
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Age and overall health
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Whether a transplant is needed and available
Some people make a full recovery. Others may need lifelong care or liver transplant. In many cases, survival improves if ALF is caught early.
Liver transplant may be necessary in severe cases. To understand transplant decisions better, read what disqualifies you from a liver transplant.
Takeaway
Acute liver failure is a rare but serious condition defined by sudden liver injury, problems with blood clotting (INR ≥ 1.5), and signs of brain dysfunction such as confusion or sleepiness — all in someone without a history of chronic liver disease. It can be caused by medications like acetaminophen, viral hepatitis, autoimmune disorders, or other less common conditions. Because it progresses quickly, acute liver failure is a medical emergency that requires immediate hospital care. Early diagnosis and treatment, including liver transplant when needed, significantly improve the chances of survival.
Worried about your liver health? Ribbon Checkup’s at-home liver test kits give you expert insights in a simple, easy-to-understand way.
Related Resources
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The Ribbon Liver Test: A Simple, Science-Backed Way to Track Liver Health from Home
Learn how you can monitor your liver health easily with this accurate at-home test. -
Early Detection of Liver Disease
Find out how recognizing symptoms early can help prevent serious complications like ALF. -
What Disqualifies You from a Liver Transplant? Eligibility, Denial, and What Comes Next
Understand transplant criteria and when it becomes a necessary treatment option.
References
Acute liver failure. (n.d.). Mayo Clinic. Retrieved August 30, 2025, from https://www.mayoclinic.org/diseases-conditions/acute-liver-failure/symptoms-causes/syc-20352863
Girish, V., Royer, A., & John, S. (2025). Acute liver failure. In StatPearls. StatPearls Publishing.
Liver failure. (2023, September 6). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/17819-liver-failure
Liver transplant. (n.d.). Mayoclinic.org. Retrieved August 30, 2025, from https://www.mayoclinic.org/tests-procedures/liver-transplant/about/pac-20384842
(N.d.-a). Medscape.com. Retrieved August 30, 2025, from https://emedicine.medscape.com/article/177354-overview
(N.d.-b). Hopkinsmedicine.org. Retrieved August 30, 2025, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/acute-liver-failure
