How long does alcohol stay in your system?

 I noted in my previous post (More medical results suggesting that wines are usually safe to drink) that it is often difficult for drinkers to estimate their own intake. This is because even Small changes in wine alcohols can make a big difference. I presented a table showing the blood alcohol concentration for an average 130-pound woman who consumes two 5-ounce glasses of wine over 1.5 hours. It looked like this:

Alcohol     Blood alcohol
content     concentration
  12%          0.065%
  13%          0.073%
  14%          0.081%
  15%          0.088%

So, let’s look at how it gets like this. Alcohol enters your stomach as its first stop. Here, if you produce enzymes known as alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) then these break down some of the alcohol, thus preventing it from entering your bloodstream. Sadly, studies have shown that women tend to have lower levels of ADH than men; and people who drink regularly have lower ADH levels than people who rarely or never drink (Cleveland Clinic).

From the stomach the alcohol goes into the small intestine, where it is transferred to your bloodstream. This is when you notice it. The liver then picks up the alcohol from the blood, and starts to convert it to acetaldehhyde and then acetate, using ADH, ALDH, cytochrome P450 (CYP2E1) and catalase (Overview: how is alcohol metabolized by the body?) — see the diagram if you want the details. About 90% is processed by the liver, with the rest coming out via your kidneys (to your urine), lungs (to the air) and skin.

Alcohol typically stays in your system for about 1 hour per standard drink consumed. One standard drink is about 14 grams of ethanol (ie. alcohol), the amount found in (Cleveland Clinic):

• 12 ounces of regular beer with 5% ethanol (about one can of beer)
• 5 ounces of wine with 12% ethanol (about one glass of wine)
• 1.5 ounces of distilled spirits (80 proof) with 40% ethanol (about one shot).

Alcohol takes around 60—90 minutes to reach peak levels in your blood, before the body begins breaking it down. The half-life of alcohol (how long it takes for your body to get rid of half of it) is 4—5 hours. However, you need about 5 half-lives to get rid of alcohol completely — so, it takes about 25 hours for your body to get clear all of the alcohol.

Furthermore, alcohol can be detected:

• in blood for 6 to 12 hours,
• in breath and saliva for 12 to 24 hours,
• in urine for 12 to 24 hours (ethanol test), but up to 80 (EtG test) to 130 hours (5.5 days), and
• in hair for up to 90 days.

There is even a biomarker called Phosphatidylethanol (PEth) that reflects alcohol intake, and can be detected in urine up to 14 days.

The exact duration of alcohol detection varies based on characteristics of your body like:

• body weight — the less you weigh then the less water you have in your body; and since alcohol goes into the water in your blood, if you have less water then your blood alcohol concentration (BAC) will be higher,
• metabolism — some health conditions can make it harder for your body to process alcohol,
• medications — prescription medicines and over-the-counter medications can have interactions with alcohol,
• age — the speed of alcohol processing slows down as we get older,
• gender — women take longer to process alcohol than men (see above),
• your ancestry — we all have different genes, which may have an effect on alcohol processing, and
• the amount of alcohol consumed.

It is usually better to consume alcohol with food. However, food changes how your body processes alcohol but not how fast it can do it (Cleveland Clinic). Food makes the alcohol hang on in the stomach for a while, and your stomach then gets time to break down some of the alcohol before it moves into the small intestine, and thus into the bloodstream.

Caffeine is sometimes recommended, as it is a stimulant, which can perk you up and make you feel less intoxicated (Cleveland Clinic). However, you can then lose track of how much you’ve had to drink; and the caffeine won’t clear the alcohol from your system any faster.

It is also important to consider the effect on your brain of drinking too much. Moderate drinkers have been seen as those who have seven or fewer drinks per week, while heavy drinkers have had eight or more drinks per week. The latter can have problems (Eight or more drinks per week linked to signs of injury in the brain).

As a final aside, there is also a thing known as “auto brewery syndrome” (Man with rare condition that turns carbs into alcohol in his stomach). Here, your body turns sugary and starchy foods (ie. carbohydrates) into alcohol in your stomach, via endogenous ethanol fermentation (a.k.a. gut fermentation syndrome). So, people with this condition can get drunk simply by eating a slice of cake. This syndrome has appeared in TV episodes of both Chicago Med and Doc Martin.