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Depending on how much you have consumed, the type of test used, and some biological factors about the person drinking the alcohol, the length of time the substance can be detected in your system can vary widely.
A blood test can measure the alcohol in your body up to 6 hours after your last drink, while breathalyzer tests work between 12 and 24 hours.
Urine tests, such as the ethyl glucuronide (EtG) test, are also effective for approximately 12 to 24 hours after use. This method tests for ethyl glucuronide, a breakdown product of ethanol, which is the alcohol found in alcoholic beverages.
Alcohol can also be detected in hair follicles for up to 90 days after consumption
How is alcohol measured in your body?
When you take a test that measures how much alcohol is in your system, the total amount of alcohol drunk is not measured. Alcohol tests measure blood/breath alcohol concentration (BAC) levels. Your BAC shows the amount of alcohol in your bloodstream or breath, shown by the amount of ethanol (in grams) in 100 milliliters of blood or 210 liters of breath.
BAC can be used in breath, blood, or urine tests, and is usually displayed as a decimal. A standard drink typically increases BAC levels by 0.02 in the 45 to 60 minutes it takes your body to absorb the alcohol (source). A standard drink is the equivalent of:
One can of 5% beer (12 fluid ounces)
A small glass of 12% wine (5 fluid ounces)
A single shot of 40% spirits, such as gin, whiskey, or rum (1.5 fluid ounces)
On average, your body can absorb a standard drink every 60 minutes, which lowers your BAC levels by about 0.16. So if you consume an alcoholic drink every hour, your BAC levels will continue to rise.
Gender: Generally, women have a higher percentage of body fat and a lower percentage of water in their bodies than men. This is not true for everyone, but it can cause alcohol to stay in a woman’s system longer.
Food – Alcohol is absorbed in the digestive tract, so the presence of food slows this process down, making the alcohol stay in your system longer. However, it does help reduce the feelings you get from drinking alcohol, ie how ‘drunk’ you feel.
Body Composition: People with smaller body frames are likely to have higher BAC levels for the same amount of alcohol as someone who is taller than them, due to the higher concentration of alcohol in smaller bodies.
Medications: Some medications, such as antidepressants and antibiotics, can affect the way your body processes alcohol. Always consult your doctor for advice if you plan to consume alcohol while using medication.
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