How Alcohol Works

The science of getting drunk (or why your liver hates you)

May 15, 2013 at 9:25 am


lcohol comes in several forms, at least in terms of a physical carbon-hydrogen-hydroxyl compound. There’s rubbing alcohol, methanol, assorted fuels and solvents, but the alcohol that’s most relevant (for a drinking issue) is ethyl alcohol or ethanol, the less toxic, ingestible psychoactive chemical found in booze.

Ethanol is a simple molecule, produced by fermenting sugars and/or starches. It is colorless at room temperature, volatile, flammable and entirely unpleasant to taste unless diluted with water. Spirits such as vodka, whiskey and tequila are generally 40 percent alcohol, whereas wine hovers in around 12 percent and most beers (unless you get a specialty craft brew) have about 4 percent pure alcohol (the remainder is a non-ethanol liquid). 

Humans have been producing ethanol and getting drunk on it since the Neolithic period, making brewing booze one of mankind’s oldest pastimes (besides sex). But how does alcohol work? And why do we get drunk … and like it? 

The exact science of ethanol metabolism is always undergoing more research, but the following is a general account of how alcohol affects you as it travels through your body.


Ethanol is a central nervous system depressant, able to permeate cell membranes and the blood-brain barrier to affect all parts of the body. And the side effects, one of which is feeling drunk, begin at the first drink.

Alcohol starts being absorbed into your body once it hits your stomach and continues absorption as it moves through the small intestine. How quickly it reaches your bloodstream depends on the proof of the alcohol as well as whether or not you have food in your stomach (food slows down alcohol absorption).

From the guts, alcohol journeys to the liver to be metabolized. The liver breaks down ethanol, oxidizin it for elimination. The average person can eliminate 0.5 ounces of alcohol (the amount in a single can of beer) in one hour. Alcohol in excess of what your body can eliminate is absorbed and travels through the bloodstream, increasing your blood alcohol level.

Alcohol unprocessed by the liver moves onto the heart. In the heart, ethanol reduces the force of contractions, decreasing blood flow and lowering blood pressure. It is then pumped from the heart into the lungs, which oxygenate the blood. From here, some alcohol passes through membranes into your alveolar sacs and is exhaled. (This is why cops can use a breathalyzer to determine how drunk you are: The ratio of the concentration of alcohol in your blood to the boozey breath evaporating out of the alveolar air is 2,100:1.)

Alcohol also impedes your ability to produce antidiuretic hormones, preventing the kidneys from reabsorbing as much water as they should be. This means you pee a lot. (And that there’s no such thing as “breaking the seal.” Alcohol makes you have to pee regardless of how long you try to hold it.)


Once the alcohol is in your bloodstream, it travels to your brain, affecting various brain centers including your cerebral cortex (in charge of attention, thought, language, consciousness); limbic system (in charge of emotion, behavior, motivation, long-term memory); cerebellum (in charge of motor function); hypothalamus and pituitary gland (in charge of hormone secretion, metabolic processes); and the medulla (in charge of cardiac, respiratory, vasomotor and autonomic functions) — respectively entering each part in concert with increasing blood alcohol levels.

For example, in your cerebral cortex, alcohol slows thought processes and interpretation of stimuli, increasing reaction time and decreasing inhibitions. In the cerebellum, alcohol messes with your movement and balance leading to the staggering and swaying of a “falling-down” drunk. In the medulla, excessive alcohol consumption impedes autonomic function, which could lead to death. 

Alcohol also acts on the central nervous system, binding to your neurotransmitters and interfering with how your nerve cells talk to each other and other cells. 

When ethanol attaches to excitatory glutamate, instead of receiving a message from another cell, your brain gets booze, disrupting the normal flow of information. This causes slow reaction times, slurred speech and memory loss. When alcohol bonds to inhibitory GABA receptors, which normally slow the brain activity, it makes them more receptive, further depressing your nervous system. Alcohol also stimulates the production of dopamine and endorphins, the feel-good chemicals, which produce the pleasurable experience of drinking — happy, self-confidence. 

But while the initial high of alcohol is fun, the more you drink, the more damage you do to your body and the worse you feel, especially the next morning.


While the exact science of a hangover is foggy, there are some common beliefs regarding what makes the experience so miserable.

First of all, alcohol use causes dehydration. As mentioned previously, alcohol stops your kidneys from absorbing all the water they need to, making you pee more and upsetting your delicate mineral balance. Your liver also steals water from other parts of your recovering body to continue processing the leftover ethanol, causing more dehydration. Symptoms of dehydration include headache, lightheadedness, weakness, dizziness and a slew of other sucky feelings. 

Alcohol also irritates the lining of the stomach and intestines. It increases gastric acid, inflames the stomach lining and delays stomach emptying, which can all result in pain, nausea, vomiting and upset stomach. As the liver continues to break down the ethanol, it also releases acetic acid (basically vinegar), which can make you feel like crap.

Alcohol use also disrupts the circadian rhythms of sleep and causes low blood sugar, which makes you tired and shaky. (It also makes you want cheese fries before you go to sleep.) 

And despite what any health store or infomercial says, the only “cure” for a hangover is prevention.


STAGE 1: “Alcohol Rules!” or The Euphoria Stage

Blood Alcohol Content: 0.03-0.12 percent (one to two drinks*)

What happens: increased overall feeling of happiness; liquid confidence; decreased anxiety; flushed skin; loss of fine muscle coordination.

Likely interests/activities: interacting with others, discussing current events, laughing at things that aren’t that funny, finding more alcohol.

STAGE 2: “I’m Really Drunk!” or The Slow Stage

BAC: 0.09-0.25 percent (three to five drinks*)

What happens: sedation; loss of balance; delayed reaction time; blurred memory and vision; comprehension is impaired.

Likely interests/activities: inviting more people out, jokingly blaming your problems on Obama, flirting with appropriately aged people, stacking things up, eating snacks, speaking loudly, dancing.

STAGE 3: “Where Am I!?” or The Confusion Stage

BAC: 0.18-0.30 percent (six to nine drinks*)

What happens: increased memory impairment; continued sensory delay; staggering; the “spins”; slurring; nausea and vomiting.

Likely interests/activities: climbing on things, telling people what you really think, listening to music you liked 10 years ago, flirting with old dudes/young women, eating questionable combinations of fried side items — possibly White Castle.

STAGE 4: “Who Am I??” or
The Drunk Stupor Stage

BAC: 0.25-0.40 percent (nine-plus drinks*)

What happens: intermittent loss of consciousness; severe coordination issues; loss of muscle control, including bladder; blacking out; barfing, even if you’re unconscious; respiratory depression

; decreased heart rate.

Likely interests/activities: falling asleep standing up, hugging friends/acquaintances/strangers, not remembering how you got home, laying in the fetal position next to the toilet.

STAGE 5: “_____“ or
The Coma Stage

BAC: 0.35-0.50 percent (bad idea amount*)

What happens: coma then possibly death.

Likely interests/activities: finding a place to sleep; subconsciously trying to not die.

*Depending on age, gender, weight, health, etc.