Blood Alcohol Test: About This Test

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Band tied tightly above elbow, with blood being drawn from vein at bend of elbow

What is it?

A blood alcohol test measures the amount of alcohol in the body. This measurement is called the blood alcohol concentration, or BAC.

The blood alcohol test measures only the amount of alcohol in the blood at the time the sample is taken. It does not show how long you've been drinking or whether you have an alcohol-use problem.

Why is this test done?

A test for blood alcohol level is done to:

  • Check the amount of alcohol in the blood if you are suspected of being legally drunk.
  • Find the cause of an altered state of mind, such as unclear thinking, confusion, or coma.

How is the test done?

A health professional uses a needle to take a blood sample, usually from the arm.

When should you call for help?

Call 911 anytime you think you may need emergency care. For example, call if:

  • You are very confused or can't think clearly.
  • You are thinking about killing yourself or about hurting others.
  • You have a seizure.
  • You vomit blood or what looks like coffee grounds.

Call your doctor now or seek immediate medical care if:

  • You have new or worse symptoms of withdrawal, such as trembling, feeling restless, and sweating.
  • Your withdrawal symptoms come back after not bothering you for days or weeks.
  • You cannot stop vomiting.

Watch closely for changes in your health, and be sure to contact your doctor if:

  • You need help to stop drinking.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

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The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.