Blood Alcohol Level
A blood alcohol test measures the amount of alcohol (also called ethanol) in a sample of your blood.
A blood alcohol test measures the amount of alcohol (also called ethanol) in a sample of your blood. Alcohol is the ingredient in beer, wine, and distilled spirits (liquor) that makes you feel intoxicated (drunk). When you have an alcoholic drink, your digestive tract quickly absorbs the alcohol. It then enters your bloodstream and stays there until your liver can break it down and filter it out of your blood. Your liver needs time to do this. If you consume alcohol faster than your liver can get rid of it, your blood alcohol levels will rise. The higher these levels rise, the more intoxicated you'll feel. There are a few blood tests that can measure whether a person has been drinking alcohol. The most common is the blood alcohol concentration/content (BAC) test. This test shows the amount of alcohol in your blood for up to 12 hours after drinking. Other blood tests measure substances that may stay in your blood for weeks after you've had alcohol. These tests are typically used to test for alcohol use disorder (AUD) or to check whether a person recovering from AUD has stayed sober. Other names: blood alcohol level test, ethanol test, ethyl alcohol, blood alcohol content
Why is this test ordered? You may need a blood alcohol test if you are suspected of drunk driving and/or have symptoms of intoxication. These include: Difficulty with balance and coordination. Slurred speech. Slowed reflexes. Nausea and vomiting . Mood changes. Poor judgment. You or your child may also need this test if there are symptoms of alcohol poisoning. In addition to the above symptoms, alcohol poisoning can cause: Confusion. Irregular breathing. Seizures . Low body temperature.
Clinical Interpretation
Blood alcohol level results may be given in different ways, including percentage of blood alcohol content (BAC). The legal limit for BAC is usually 0.08%, but this limit is lower in certain states and for certain driver classifications. The effects of alcohol and your level of impairment increase as your BAC increases. Typical results are below. 0.01 to 0.05% BAC: You may feel relaxed, less alert, and have a slight loss of judgement. 0.06-.15% BAC: You may have slurred speech, reduced muscle coordination and impaired judgement, memory or balance. 0.16 to 0.30% BAC: In this range, you will feel more serious signs of intoxication such as difficulty walking and speaking. You may also feel drowsy, confused, and nauseated. You may experience gaps in memory (blackouts), vomiting or loss of consciousness. Over 0.31% BAC: Levels are especially dangerous and may even be fatal. You may lose consciousness, have trouble breathing, or go into a coma. The timing of this test can affect the accuracy of the results. A blood alcohol test can detect alcohol in your system for up to about 12 hours after your last drink. Other factors can also affect your BAC and your level of impairment, including: Weight. Age. Sex. Type of alcohol. How quickly you drank. How much you ate before you drank. Medicines you're taking. Sensitivity (tolerance) to alcohol. If you have questions or concerns about your results, you may want to talk to a health care provider and/or a lawyer. Learn more about laboratory tests, reference ranges, and understanding results .
Clinical Protocol & Patient Advice
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You don't need any special preparations for a blood alcohol test.
Usage Guidance
- Reference ranges vary by laboratory. Always discuss your specific results with a qualified healthcare professional.
Source: MedlinePlus, National Library of Medicine. View the original.