Does this test have other names?
Blood alcohol test
What is this test?
This test measures the amount of alcohol, or ethanol, in your blood.
When you drink alcohol, more than 90% of it is processed by your liver. The rest leaves
your body in your urine, sweat, and breath. Ethanol moves quickly from your digestive
tract – mostly your stomach – and is absorbed into your bloodstream. Your blood alcohol
level continues to rise for 30 to 90 minutes after you have your last alcoholic beverage.
This test is used by law enforcement agencies and hospitals to find out the concentration
of alcohol in a person's blood. In an adult or teen, it can be used if a driver may
be driving under the influence. In children, it can be used to check for alcohol poisoning.
Although alcohol poisoning can be fatal, most such deaths are accidental. Besides
wine, spirits, and beer, ethanol is found in a surprising number of common household
items. Young children sometimes get alcohol from:
Perfume, cologne, and body sprays
Over-the-counter cough, cold, and allergy medicines
Most cases of alcohol poisoning in young children are caused by drinking cologne or
If you suspect that a young child has swallowed alcohol from any household source,
seek medical help right away. Call the poison control center right away at 800-222-1222.
Or call your local emergency number at 911.
Why do I need this test?
You may have this test if a police officer thinks you of driving under the influence.
A breath test, or analysis, gives faster results, but a blood test is more accurate.
You or your child may also have this test if your healthcare provider suspects alcohol
poisoning. Teens and youth are at particular risk for binge drinking. This can cause
alcohol poisoning. If an adult or child comes to the ER unconscious, or appears drunk
or disoriented, this test is used to find the ethanol concentration in the blood.
What other tests might I have along with this test?
If you are in the ER, your doctor may also order other tests to screen for chronic
alcohol toxicity. The tests may include:
Serum glucose, to check your blood sugar level
Serum electrolytes, to check for dehydration
Complete blood count, to look at the major parts of your blood
Blood urea nitrogen and creatinine, to check how your kidneys are working
Liver function tests
Head CT scan, to check for head trauma or stroke
Blood tests, urine tests, or both, to look for drugs of abuse
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Blood alcohol concentrations are given in different ways. Law enforcement agencies
use grams per deciliter (g/dL). Healthcare professionals use milligrams per deciliter
(mg/dL) or, in some instances, millimoles per liter (mmol/L). For example, the legal
limit for ethanol concentration can be stated as 0.08 g/dL, 80 mg/dL, or 17 mmol/L.
Blood alcohol concentrations will be different for each person. They are based on
things such as body weight, metabolism, and the amount of alcohol consumed.
Here are some blood alcohol concentration levels and what they do to your body:
0.00 g/dL – Sober
0.03 g/dL – May feel a slight buzz, but without having trouble talking, seeing, or
keeping your balance
0.05 g/dL – Feeling buzzed or relaxed
0.08 g/dL – Legally drunk in the U.S. You may have trouble balancing, talking, and
seeing straight. If you drink often, you may not have any symptoms of blood alcohol
poisoning at this point, but damage to your brain and liver are still occurring.
0.10 g/dL – Impaired judgment, decreased attention, trouble walking, and mood changes
0.15 g/dL – Blackouts and lack of physical control
0.20 g/dL – "Sloppy drunk," vomiting, confusion, staggering around
0.30 g/dL – Unconscious, stupor
0.40 g/dL – Coma or possible death
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Timing is important. Having this test too soon or too long after drinking alcohol
can affect your results. The test is only accurate within a 6- to 12-hour window.
How do I get ready for this test?
You don't need to prepare for this test. But be sure your healthcare provider knows
about all medicines, herbs, vitamins, and supplements you are taking. This includes
medicines that don't need a prescription and any illicit drugs you may use.