How Long Does Alcohol Stay in Your System?

Various laboratory and field tests exist that allow for the detection of alcohol consumption for a period of time after the last drink. These involve testing the urine, breath, saliva, blood or hair, and each has a certain window of time during which alcohol use can be detected.

Alcohol is cleared from the body by enzymes that metabolize it after it has been ingested. In general, a healthy body can metabolize and clear about one ounce of alcohol per hour. However, alcohol metabolism is unpredictable, with many factors that affect the rate at which the body can process alcohol. These factors can significantly differ between individuals and even between different situations in the same individual.

In this article, we examine these factors and their effects on the tests used to detect alcohol use. 

Alcohol Test Detection Times

The duration that alcohol remains detectable in individuals depends heavily on the type of test used, and various factors that differ between individuals. The test with the shortest detection window is a blood test, and hair testing provides the longest time frame for detecting alcohol after the last drink.

There is great demand for new and better alcohol detection testing from employers, hospitals, and law enforcement, so new and more sensitive detection tests are being commercially developed all the time. 

Urine

How long can alcohol be detected in urine? Commonly used alcohol urine tests can detect alcohol use for 10-12 hours after exposure. More advanced forensic tests can detect it for 80 hours after the last drink.

Blood

Alcohol blood tests used for blood alcohol screening can detect alcohol use for up to 12 hours after the last drink. Genetic and other factors have a strong influence over how long alcohol stays in your blood, so this particular method of detection is especially variable between individuals, making it somewhat unreliable as a standardized test.

Breath

How long does alcohol stay in your breath? Alcohol is detectable in the breath for about 24 hours. The alcohol breath test (breathalyser), however, has been shown to correlate poorly with blood alcohol concentration.

Saliva

How long does alcohol stay in your saliva? Alcohol detection in saliva is possible for 1-5 days after the last drink. Alcohol saliva tests are rapid and inexpensive, and have been suggested as a replacement for the breathalyser.

Hair

Hair follicle alcohol test detection times are from a few weeks after consumption to 90 days for a standard 3 cm hair sample. Cases of alcohol use being detected by hair analysis 17 months after use has been documented.

How Does the Body Process Alcohol?

The liver is heavily involved in metabolizing (breaking down) alcohol; alcohol is a toxin, and the liver is the body’s main way of detoxifying the body from toxic substances. The liver produces various enzymes that break down alcohol: most notably alcohol dehydrogenase and aldehyde dehydrogenase.

Unfortunately, the metabolites of alcohol (the chemicals that result after alcohol is broken down in the body) are also highly toxic, particularly to the liver and pancreas. These toxins are responsible for the association between alcohol and numerous cancers, as alcohol’s metabolites create the oxidative cellular DNA damage that causes cancer.

Differences in the genetic control of these enzymes is the reason that people of similar physical characteristics can have great variations in how they “handle their drinks.” Interpersonal differences in these genes also play a role in determining individuals’ susceptibility to alcoholism.

Breastfeeding and Alcohol

Alcohol and breastfeeding do not fit together safely. In fact, no amount of alcohol is safe for the breastfeeding child; exposure to alcohol puts babies at risk for developmental delays in their motor skills and disrupts their sleep patterns. Alcohol reduces breast milk production and causes babies to drink less breast milk (about 20% less). When a breastfeeding mother ingests a single serving of alcohol, the alcohol will remain present in the breast milk for about three hours.

Factors Affecting Blood Alcohol Concentration (BAC)

There are a number of factors that affect BAC, which makes lab and field tests of BAC relatively inconsistent and unreliable. The most influential of these are the genetics of the particular individual, especially the genetics affecting alcohol metabolism. Other important factors include:

• Strength of drink: and the amount of alcohol consumed
• Time: over which the alcohol was consumed
• Food: alcohol absorption is slowed when consumed with food
• Gender: women usually metabolize alcohol more slowly than do men
• Weight: smaller body size leads to higher BAC; body fat content is also a factor
• Age: alcohol metabolism slows with age
• Race: some races (most notably East Asians and Native-Americans) may lack some of the enzymes to break down alcohol
• Time since last drink: alcohol metabolism is faster when there is time between drinks
• Medications: certain medications affect alcohol metabolism

How Long Does it Take to Sober Up?

Alcohol affects every individual differently, and there is wide variability between individuals in how quickly they metabolize alcohol based on genetic and environmental factors. However, as a general rule, a person can metabolize an ounce of alcohol per hour.

If you have concerns about alcohol use in yourself or another person, please feel free to contact us at The Recovery Village Ridgefield for a confidential discussion with one of our staff.