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Blood Alcohol

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Using rubbing alcohol to clean the skin before inserting a needle to draw blood.
  • You have high blood ketones, as in diabetic ketoacidosis.
  • Taking cough medicines that contain alcohol or herbal supplements, such as kava or ginseng.
  • Drinking other alcohols, such as isopropyl alcohol or methanol.

Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.

Things that affect how quickly the blood alcohol level rises in the body include:

  • The number of drinks per hour. As you increase the number of drinks per hour, your blood alcohol level steadily increases.
  • The strength of alcohol (proof or percentage) in the drink.
  • Your weight. The more you weigh, the more water is present in your body, which dilutes the alcohol and lowers the blood alcohol level.
  • Your sex. Women's bodies usually have less water and more fat than men's bodies. Alcohol does not go into fat cells as well as other cells, so women tend to keep more alcohol in their blood than men do. Also, a woman's hormones may affect the breakdown of alcohol.
  • Your age. One drink raises the blood alcohol level of an older adult more than it does for a young adult.
  • Eating. Food in the stomach absorbs some of the alcohol. The blood alcohol level will be higher if you do not eat before or during drinking.

WebMD Medical Reference from Healthwise

Last Updated: March 12, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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