How Long to Abstain from Alcohol Before a Liver Function Test: A Complete Guide

By Your Health Magazine

Introduction

Liver function tests or LFTs are laboratory tests performed to find out if there is liver damage. These tests use liver enzymes as markers to pinpoint the source of the problem. In preparation for an LFT, you must fast for 8–12 hours, which means you can’t eat or drink anything besides water. But, can you drink alcohol before fasting for 12 hours?

You should abstain from alcohol for at least 24 hours before your test. This is because alcohol has significant effects on LFTs, such as elevating the levels of certain liver enzymes like AST, ALT, and GGT. If you are a long-term heavy drinker, drinking may lower the levels of total albumin and liver proteins while elevating bilirubin levels. In short, alcohol causes inaccurate LFT results.

For those monitoring their liver health over time, at-home liver health monitoring tools may offer a helpful way to observe trends between tests.

Why Liver Function Tests Matter

Liver function tests are important in assessing liver health. LFTs are especially vital if you have a high risk of liver disease and damage due to a family history of liver disease, heavy drinking, obesity, hepatitis, diabetes or hepatotoxic medicine. These tests assess liver markers that can indicate liver injury, as well as other diseases:

Marker	Normal Levels	Elevated Levels		Low levels
Alanine aminotransferase (ALT) / SGPT	4-36 U/L	>36 U/L		<4 U/L
		Causes: Liver cirrhosis Fatty liver Liver tumor or cancer Liver tissue death Hepatitis Hemochromatosis	Liver ischemia Pancreatitis Mononucleosis Hepatic congestion Myocardial infarction Drug-induced	Causes: Vitamin B6 deficiency Chronic kidney disease
Aspartate transaminase (AST)	0-35 U/L	>35 U/L		Low
		Causes: Viral infection (hepatitis, Epstein-Barr, Cytomegalovirus) Liver cirrhosis Passive liver congestion or hypoxia	Fatty liver Alcohol- or drug-induced Heart attack Pericarditis Skeletal muscle injury Muscle inflammation	Causes: May be normal Vitamin B6 deficiency Chronic kidney disease Severe Liver Failure
Alkaline phosphatase (ALP)	30-120 U/L	>147 U/L		<44 U/L
		Causes: Space-occupying liver lesions Sepsis Liver passive congestion Primary biliary cirrhosis Drug-induced liver cell dysfunction Liver cell acute injury Intrahepatic biliary obstruction Extrahepatic bile duct obstruction Paget disease (bone)	Fracture healing Physiologic bone growth Metastatic tumor with osteoblastic reaction Some parenteral albumin preparations Pregnancy Formation of granulation tissue Benign transient hyperphosphatasemia Primary hyperparathyroidism	Hypothyroidism Pernicious anemia Hypervitaminosis D Hypophosphatemia Malnutrition
Gamma-glutamyl transferase (GGT)	0-30 U/L	>30 U/L
		Causes: Cholestasis Chronic alcoholic liver disease Neoplasms (hepatoma, metastatic disease to the liver) Drugs (phenytoin, barbiturates)	Congestive heart failure Nephrotic syndrome Systemic lupus erythematosus Sepsis Trauma Carcinoma of the pancreas
Total Bilirubin	0-1.0 mg/dl	>1.0 mg/dl
		Causes: Cholangitis Cirrhosis Hepatic congestion secondary to congestive heart failure Infectious mononucleosis Biliary obstruction Neoplasm Hepatitis Gilbert disease Dubin-Johnson syndrome Pulmonary embolism or infarct	Hemolysis Antibiotics / Antimicrobials Anticonvulsants / Psychotropics Anti-inflammatory / Immunosuppressive Cardiovascular / Antihypertensives Lipid-lowering / Metabolic agents Other hepatotoxic or hormone-related drugs
Direct bilirubin	0-0.2 mg/dl	>0.2mg/dl		Low
		Causes: Biliary obstruction Rotor syndrome Drug-induced cholestasis	Hepatocellular disease Dubin-Johnson syndrome	May not be a concern May be due to metabolic dysfunction
Prothrombin time	10 to 12 sec	>12 sec		<10 sec
		Causes: Heparin Afibrinogenemia Liver disease Vitamin K deficiency Factor deficiency (I, II, V, VII, X) Disseminated intravascular coagulation Dysfibrinogenemia Oral anticoagulants (warfarin)	Drugs affecting coagulation: Antibiotics Anabolic steroids Chloral hydrate Salicylate Antacids Allopurinol Diphenylhydantoin Phenylbutazone Quinidine Estrogens	Thrombophlebitis Vitamin K supplementation Diphenhydramine Estrogens Griseofulvin Glutethimide
Albumin	4-6 g/dl	>6 g/dl		<4 g/dl
		Dehydration (relative increase)		Hypervitaminosis A Liver disease Oral contraceptives Pregnancy Chronic glomerulonephritis Nephrotic syndrome Gastrointestinal / Nutritional Protein-losing enteropathies Poor nutritional status Chronic inflammatory diseases Severe burns Rapid IV hydration Prolonged immobilization Lymphomas Neoplasia
Total protein	6-8 g/dl	>8 g/dl		<6 g/dl
		Waldenström macroglobulinemia Dehydration Collagen vascular diseases Sarcoidosis Multiple myeloma		Overhydration Pregnancy Cirrhosis Chronic diseases Neoplasms Severe burns Low-protein diet Nephrosis Malnutrition Malabsorption
Lactate Dehydrogenase	50-150 U/L	>150 U/L		<50 U/L
		Causes: Lung infarction Kidney infarction Myocardial infarction Collagen diseases Liver diseases Central nervous system diseases Cardiopulmonary system diseases Megaloblastic anemias Hemolytic anemias Transfusions	Seizures Muscle trauma Muscular dystrophy Acute pancreatitis Hypotension Shock Inflammation Intestinal obstruction Infectious mononucleosis Hypothyroidism Tumor/Cancer	Causes: – High concentrations of vitamin C –

Among these markers, bilirubin stands out for its ability to reflect how well the liver is processing waste. High levels may indicate bile duct obstruction or liver inflammation. In between formal LFTs, some people use home-based urine tests to check for bilirubin or urobilinogen, which can be early signs of liver dysfunction

How Alcohol Affects Liver Enzyme Test Results

The liver metabolizes alcohol, and this reaction triggers a stress response where ALT and AST rise, indicating liver cell damage or inflammation. ALT and AST enter the bloodstream when there is damage or inflammation of the liver, even if you are only having a few drinks the night before your test.

Aside from ALT and AST, GGT, which is also sensitive to alcohol intake, may rise significantly within hours of consuming alcohol and can remain elevated for days, especially in regular drinkers. Bilirubin can also increase after alcohol intake, contributing to distorted test results.

If you’ve previously had borderline bilirubin readings or are observing changes in your urine color, testing for bilirubin and urobilinogen at home can be a practical way to track trends before your next lab visit.

How Long Should You Avoid Alcohol Before an LFT?

Avoid alcohol for at least 24 hours before your liver function test. If you’ve had more than one drink or drank heavily in the past few days, abstain for 48–72 hours. Your liver needs time to process and clear alcohol, and allowing this window reduces the likelihood of test inaccuracies.

Because liver inflammation doesn’t always resolve right away, some people opt to monitor their liver markers at home during alcohol abstinence periods—especially if they’ve had abnormal tests in the past or are actively making lifestyle changes.

How Many Days of No Alcohol Are Needed for Accurate Results?

Most physicians recommend 1–3 alcohol-free days to ensure accurate liver function test results. This gives the liver time to recover from temporary changes caused by alcohol. However, in some cases—particularly when there’s underlying liver disease—a full week without alcohol may be advised.

Can Drinking Two Days Before a Liver Test Affect Results?

Yes, drinking alcohol two days before a liver test can affect results, especially if you’re a moderate or heavy drinker. Elevated AST, ALT, and GGT levels may suggest liver stress or damage even when none exists—or they may temporarily mask a developing issue. If your results were unexpected, observing urine bilirubin or urobilinogen changes at home in the following days can provide added insight into liver recovery.

Fasting and Alcohol: What You Should Know

Fasting means no food or beverages (other than water) for 8–12 hours before your test. Alcohol abstinence is a separate consideration, but equally important. While fasting helps stabilize markers like glucose and triglycerides, avoiding alcohol ensures that liver enzyme results reflect your baseline status—not a temporary reaction to drinking.

Some people find that combining fasting with ongoing tracking—such as through home test kits—gives a more complete picture of their metabolic and liver health.

Is It Okay to Drink After the Liver Function Test?

Technically, yes—it is okay to drink after your liver function test, unless your doctor has advised against it. However, if you’ve had previous abnormal results or symptoms suggestive of liver stress, it’s a good idea to wait until you’ve reviewed your lab results. Staying alcohol-free during that waiting period may also give your liver more time to normalize any elevated enzymes.

Conclusion

Alcohol has a measurable impact on liver enzyme levels, and even small amounts consumed shortly before your test can influence your results. For most people, avoiding alcohol for 24–72 hours is enough to help ensure accuracy. But if you’re managing liver concerns or adjusting your lifestyle, additional tools—like at-home urine tests for bilirubin and urobilinogen—can support your health journey in between clinical visits.

Taking small, proactive steps to understand how your body responds to alcohol can help you feel more confident about your liver health and the results of your next LFT.

References

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AST test. (n.d.). https://medlineplus.gov/lab-tests/ast-test/

Content – Health Encyclopedia – University of Rochester Medical Center. (n.d.). https://www.urmc.rochester.edu/encyclopedia/content?contenttypeid=167&contentid=alkaline_phosphatase

Farhana, A., & Lappin, S. L. (2023, May 1). Biochemistry, lactate dehydrogenase. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK557536/

Lala, V., Zubair, M., & Minter, D. A. (2023, July 30). Liver function tests. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK482489/

Liver function tests. (n.d.). https://medlineplus.gov/lab-tests/liver-function-tests/

Moriles, K. E., Zubair, M., & Azer, S. A. (2024a, February 27). Alanine aminotransferase (ALT) test. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK559278/

Moriles, K. E., Zubair, M., & Azer, S. A. (2024b, February 27). Alanine aminotransferase (ALT) test. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK559278/

Prothrombin Time (PT). (2023, October 31). ucsfhealth.org. https://www.ucsfhealth.org/medical-tests/prothrombin-time-(pt)