How Long Does Alcohol Stay In Your System?

How the Body Processes Alcohol

The speed at which your body processes alcohol and the amount of alcohol you consume determine how long alcohol is in your system. Alcohol is processed, or metabolized, in the body more quickly than most substances, and a very high percentage of the amount consumed is actually metabolized. Alcohol typically enters the body through the mouth. It then travels down the esophagus and into the stomach. Alcohol metabolism begins in the stomach. Small blood vessels encounter alcohol there and begin to transport it throughout the bloodstream. Approximately 20% of the alcohol that enters the blood stream does so in the stomach. The remaining alcohol travels through the small intestine where it encounters greater concentrations of blood vessels. The 80% of alcohol that doesn’t enter the bloodstream through the stomach does so through the small intestine.

Once in the blood, alcohol is rapidly transported throughout the entire body, which is why alcohol impacts so many different body systems. Most alcohol that enters the body eventually ends up in the liver, where the vast majority of alcohol metabolism takes place. Because the liver does most of the heavy lifting in alcohol processing, it is generally the part of the body that is most impacted and damaged by long term alcohol abuse.

The two enzymes that are primarily responsible for alcohol processing are found in the liver, both of which break down ethyl alcohol (drinking alcohol) into Acetaldehyde, which is then further broken down into substances the body can absorb. Alcohol dehydrogenase (also found in the stomach) breaks down almost all of the alcohol consumed by light, social drinkers. Alcohol dehydrogenase converts alcohol into energy. Cytocrome P450 2E1 is very active in the livers of chronic, heavy drinkers. This enzyme actually drains the body of energy in order to break down alcohol.

A third enzyme, catalase, which is present in cells throughout the body, also metablizes a small amount of alcohol. Acetaldehyde released into the brain via catalase metabolism can combine with neurotransmitters to form tetrahydroisoquinolines, which some scientists believe are the cause of alcoholism (though this is controversial). These scientists believe that the presence of tetrahydroisoquinolines can be used to determine whether someone is an addicted drinker or a social drinker.

Many factors influence alcohol processing speed, and no two people metabolize alcohol at the exact same pace. However, alcohol processing is remarkably consistent for most individuals. As a general rule, most individuals process one standard drink (one beer, one glass of wine, or one shot) per hour.

The human body is very effective at processing alcohol. Between 90% and 98% of all alcohol that enters the body is metabolized and absorbed. The remaining alcohol is excreted through sweat, urine, vomit, and feces.

Blood Alcohol Concentration (BAC)

The amount of alcohol in the body is measured in blood alcohol concentration (BAC) levels. Also known as blood alcohol content, BAC is the percentage of alcohol in the blood. For example, in the United States, a BAC of 0.1 would mean that the individual’s blood is 0.1% alcohol. In most countries, a BAC 0.08 is considered legally intoxicated. A person’s BAC is the most common measure of how much alcohol remains in their system.

Factors That Influence Alcohol Processing

The amount of time that it takes for the body to process alcohol depends on a large number of factors. Some of the most important include:

  • Weight – Body weight has little impact on the speed with which the body processes alcohol, but it can greatly influence BAC and intoxication level
  • Gender – Although some experts believe men process alcohol faster than women, others feel that men generally have a lower BAC than women after counting for difference in weight due to fat composition
  • Age – In general, younger individuals will process alcohol faster and more effectively than older individuals.
  • Body composition – Low-water fatty tissue cannot absorb alcohol to the extent that high-water muscle tissue can, meaning individuals with more body fat generally have higher BAC.
  • Health – Healthier individuals will generally process alcohol faster. This is especially true of liver health. Individuals with liver damage often have great difficulty processing alcohol.
  • Genetics – Some individuals’ genetics enable them to process alcohol faster or cause them to process it slower. A primary example is many East Asian populations, who process alcohol differently than most others, leading to facial flushing and other effects.
  • Time since last meal – The more food is in the stomach, the longer it will take for the body to absorb and process alcohol, and the lower the individuals’ BAC.
  • What the alcohol was mixed with – Certain mixers cause alcohol to be absorbed by the body more quickly, such as caffeinated drinks and sports drinks, and others cause alcohol to be absorbed by the body more slowly, such as water or fruit juice.
  • Medications or other drugs – Certain medications and drugs impact how the body processes alcohol. It is therefore critical that anyone consult with their doctor before drinking while taking medication. Alcohol should never be mixed with illegal drugs.