The Pharmacology of Alcohol & the Effects on Blood

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  • 0:01 Alcohol in the Body
  • 0:51 Absorption
  • 2:23 Distribution
  • 3:10 Metabolism and Excretion
  • 4:57 Lesson Summary
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Lesson Transcript
Instructor: Lisa Roundy

Lisa has taught at all levels from kindergarten to college and has a master's degree in human relations.

A person's blood alcohol level is influenced by the way the ethanol in an alcoholic beverage is processed by the body. This process is why blood alcohol levels can increase faster than they can decrease.

Alcohol in the Body

Let's imagine that you have a headache and you take an aspirin. Does your headache go away as soon as you swallow the medicine? Of course, we know this isn't the case. It will take some time for the medicine to start to work. This is because your body has to process the aspirin. The same idea is true of alcohol. Alcohol contains ethanol, which acts as a drug and must be processed by our body.

Pharmacology is the study of how a drug acts in the body. The way a drug is processed by our bodies is described by this science. There are four pharmacological processes that take place in the body: absorption, distribution, metabolism, and excretion. This lesson will discuss the pharmacological processes of ethanol in our body.


Think about our aspirin example. An aspirin you take for a headache must first be made available by your body to use. Absorption is the process by which a drug is made available in the body fluids.

After ethanol is ingested, absorption is the process that raises a person's blood alcohol level. Greater than 50% of ingested ethanol will be absorbed within 15 minutes, but it may take up to an hour for complete absorption of the ingested ethanol. About 20% of ingested ethanol is absorbed through the stomach and 80% is absorbed from the small intestine.

The rate of absorption, and therefore the change in a person's blood alcohol level, differs based on the following factors:

  • How quickly the ethanol is ingested: The more quickly you drink, the faster your blood alcohol level will rise.
  • How much you consume: A mixed drink with two shots of rum will raise your blood alcohol level faster than one shot of rum.
  • The concentration of ethanol in the drink: Whiskey will raise your blood alcohol level faster than a beer.
  • Presence or absence of carbonation: Carbonation increases the rate of absorption and will raise your blood alcohol level more quickly. For example, scotch and soda will raise blood alcohol level faster than scotch and water.
  • The presence or absence of food: Food delays the absorption of ethanol, so your blood alcohol level will raise more slowly if you have a meal with your drink.
  • Interaction with medications: Some medicines may cause ethanol to be absorbed more quickly and others may have the opposite effect.


Distribution is the process by which a drug is delivered to different parts of the body by the blood. Remember our example of taking an aspirin for a headache? This is when the medication will kick in and start to relieve your headache. The aspirin was ingested, absorbed into the bloodstream, and has now been distributed to where it is needed.

Like the aspirin, after ethanol has been absorbed into the bloodstream, it also begins to have an effect on the body. The most obvious effects are related to the distribution of ethanol to the brain. Ethanol affects the parts of the brain that control things such as speech and movement. This is the cause of obvious signs of alcohol intoxication, such as slurred speech and difficulty walking.

Metabolism and Excretion

Metabolism is the process by which the chemical structure of a drug is altered so that it can be expelled from the body. Think back to our example of taking an aspirin for a headache one last time. Have you ever had a headache come back after the medicine wears off? This is because the aspirin you took earlier has all been metabolized. There's no more aspirin in your body that can be used to stop your headache unless you take another dose.

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