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Also known as: Ethyl Alcohol; Alcohol; EtOH; Blood Alcohol Level; BAL; Blood Alcohol Content; BAC
Formal name: Ethanol

At a Glance

Why Get Tested?

To determine if a person has consumed ethanol and to measure the amount of ethanol present

When to Get Tested?

When someone has signs and symptoms that suggest intoxication or ethanol poisoning; when a person is suspected of violating drinking-related laws, or as part of a drug testing panel

Sample Required?

A blood sample drawn from a vein in the arm, a urine sample, or sometimes a breath sample; rarely, saliva is collected. Blood, urine, and saliva samples must be sent to a laboratory for analysis. A breath sample is analyzed immediately on site using a breathalyzer.

Test Preparation Needed?


The Test Sample

What is being tested?

Ethanol is the intoxicating ingredient in alcoholic beverages such as beer, wine, and liquor. This test measures the amount of ethanol in the blood, urine, breath, or saliva.

When ethanol is consumed, the gastrointestinal tract absorbs it. Ethanol is then carried throughout the body in the blood. The body eliminates small amounts of ethanol in the urine or from the lungs upon exhalation, but the liver processes (metabolizes) most ethanol.

The liver can process about one drink an hour, with one drink being defined as the amount of ethanol in 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of whisky. A person who drinks more than one drink an hour will have an increased level of ethanol in the blood. However, certain factors affect the metabolism of alcohol, especially the amount of food consumed prior to and during drinking. The degree of a person's intoxication can vary with age, gender, weight, and whether he or she has taken other drugs that interact with alcohol.

Drinking alcoholic beverages faster than the liver can process can result in an elevated level of ethanol in the blood. This leads to signs and symptoms of intoxication such as bloodshot eyes, flushed face, slurred speech, slow response to questions or comments, impaired judgment, decreased motor skills, drowsiness or falling asleep, and/or vomiting.

With a very high blood ethanol, more serious signs and symptoms of toxicity may appear such as confusion, stupor, staggering, irregular or slow breathing, loss of consciousness, seizures, and low body temperature (hypothermia). A very high blood ethanol can be fatal.

Long-term, excessive alcohol use can lead to the development of several medical problems such as liver disease, cardiovascular problems, depression and anxiety. (Read more about this in the article on Alcoholism.)

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm. A breath sample is collected by blowing into a tube or balloon. Urine samples are collected in plastic containers. Sometimes a single urine sample is collected and sometimes two separate samples may be collected with the first discarded and the second collected after a measured time. Saliva samples are often collected from the mouth using a swab.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

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Article Sources

« Return to Related Pages

NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

50 Signs of Visible Intoxication. Oregon Liquor Control Commission. Available online at thorugh Last revised June 2012. Accessed June 9, 2014.

Diseases and Conditions: Alcohol Poisoning. Mayo Clinic. Available online at through Last revised July 23, 2013. Accessed June 9, 2014.

Blood Alcohol Level: Are You Legally Drunk? Nolo Network. Available online at through Accessed June 10, 2014.

Effects of Blood Alchol Concentrations. U.S. Centers for Disease Control and Prevention. Available online at through Last updated February 11, 2011. Accessed June 10, 2014.

Preeti Dalawari. Ethanol Level. Medscape. Available online at through Last updated February 4, 2014. Accessed June 10, 2014.

Alcohol Urine. Clinical Lab Navigator. Available online at through Last updated October 6, 2013. Accessed June 10, 2014.

Message to Our Nation's Health Care Providers. U.S. Department of Health and Human Services. Available at through Issued January 13, 2013. Accessed June 10, 2014.

Law Enforcement Access to Patients and Patient Information. University of Chicago HIPAA Program Office. Available online at through Issued November 26, 2007. Accessed June 10, 2014.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. 4th edition. St. Louis: Elsevier Saunders; 2006, Pg 2269.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO. Pp 392-393.

Whetstone W. (2005 August 8, Updated). Breath alcohol test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at

(2005 December 5). Highway Safety Programs; Conforming Products List of Screening Devices to Measure Alcohol in Bodily Fluids. National Highway Traffic Safety Administration [On-line information]. PDF available for download at through

Harty-Golder, B. (2003 September). Liability in the lab. Medical Laboratory Observer v 35(9) [On-line journal]. Available online at through

(2000 Updated). Alcohol Metabolism. National Institute on Alcohol Abuse and Alcoholism, Alcohol Alert no. 35; PH 371 [On-line information]. Available online at through

Barone, P. and Crampton, J. (2003 August). Blood Alcohol Testing: Understanding quantitative blood alcohol testing in drunk driving cases. Michigan Bar Journal [On-line journal]. Available online at through

Kadehjian, L. (2002 June). Urine Alcohol Testing is a Valuable, Underused Tool. Clinical & Forensic Toxicology News [On-line journal]. Available online through

(2002 February). Urine Alcohol Testing. Marshfield Laboratories [On-line information]. Available online through

(2004 December 20, Updated). Alcohol Intoxication Testing. North Carolina Wesleyan College, [On-line lecture]. Available online at through

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 422-423.

Brothers, E. and Doty, C. (Updated 2009 October 14). Toxicity, Ethanol. eMedicine [On-line information]. Available online at through Accessed April 2010.

Ramachandran, T. and Gellido, C. (Updated 2009 June 15). Alcohol (Ethanol) Related Neuropathy. eMedicine [On-line information]. Available online at through Accessed April 2010.

Grenache, D. and McMillin, G. (Reviewed 2009 May). Alcohol Abuse. ARUP Consult [On-line information]. Available online at through Accessed April 2010.

Mayo Clinic Staff (2008 December 11). Alcohol poisoning. [On-line information]. Available online at through Accessed April 2010.

O'Connor, P. (Revised 2008 July). Alcohol. Merck Manual for Healthcare Professionals [On-line information]. Available online at through Accessed April 2010.

Pagana K, Pagana T. Mosby's Manual of Diagnostic and Laboratory Tests. 3rd Edition, St. Louis: Mosby Elsevier; 2006, Pp 241-242.