Being drunk is the state your body and brain enter when alcohol builds up in your bloodstream faster than your liver can break it down. Alcohol suppresses your brain’s excitatory signals while amplifying its calming ones, which is why intoxication feels like a sliding scale from relaxed and warm to clumsy, confused, and unable to function. The experience changes dramatically depending on how much you’ve had, how fast you drank, and your individual biology.
What Alcohol Does to Your Brain
Your brain runs on a balance between two chemical messaging systems: one that excites neurons and one that calms them. Alcohol disrupts both at the same time, which is why its effects are so wide-ranging.
On the calming side, alcohol boosts the activity of your brain’s main inhibitory system. It increases the release of calming chemical signals, particularly in brain regions tied to stress and anxiety, like the amygdala. Even at low doses, alcohol enhances a type of background inhibition in your neurons, which is why even one or two drinks can make you feel noticeably more relaxed. This same system is responsible for the sedative, coordination-impairing, and memory-disrupting effects of heavier drinking.
On the excitatory side, alcohol does the opposite: it suppresses the receptors responsible for keeping your brain alert and responsive. Acute alcohol exposure inhibits excitatory signaling, slowing down the speed at which your neurons fire and communicate. This is why reaction time drops, thinking gets sluggish, and speech starts to slur. It’s not that alcohol “turns off” your brain. It tilts the entire balance toward sedation, making everything from decision-making to walking in a straight line progressively harder.
How It Feels at Different Levels
Blood alcohol concentration (BAC) is the standard measure of how much alcohol is circulating in your blood. Your experience of being drunk changes in predictable stages as BAC rises, though individual tolerance, body weight, food intake, and genetics shift the exact thresholds from person to person.
At a BAC around 0.02, most people feel a subtle mood shift. There’s a slight warmth in the body, a loosening of judgment, and a mild sense of relaxation. You might not feel “drunk” at all, but your ability to track moving objects and split your attention between two tasks is already declining.
By 0.05, the effects become more obvious. Behavior gets louder or more exaggerated, inhibitions drop, and fine motor control starts to slip. Focusing your eyes takes more effort. Most people describe this range as a pleasant buzz, though alertness is measurably lower.
At 0.08, the legal driving limit in the United States, muscle coordination is clearly impaired. Balance, speech, vision, and reaction time all suffer. Short-term memory starts to fail, self-control weakens, and it becomes harder to detect danger. This is the point where most people would say they feel drunk.
At 0.10, deterioration is unmistakable: slurred speech, poor coordination, and noticeably slowed thinking. By 0.15, muscle control is severely compromised, balance is unreliable, and vomiting commonly occurs, especially in people who don’t drink heavily or who reached that level quickly.
Why Judgment Goes First
One of the defining features of being drunk is impaired decision-making, and there’s a reason it happens so early. The prefrontal cortex, the part of your brain responsible for planning, impulse control, weighing consequences, and organizing your behavior, is especially sensitive to alcohol. Executive function is a broad term for the mental skills this brain region handles: working memory, mental flexibility, attention, and problem-solving. Alcohol suppresses all of them.
This creates a well-known paradox of drunkenness. The same faculty you’d need to recognize that you’re too impaired to drive, send a text, or pick a fight is the one alcohol shuts down first. People who are drunk frequently believe they’re performing better or more normally than they actually are, precisely because the self-monitoring system is offline.
How Your Body Processes Alcohol
Your liver does the heavy lifting when it comes to clearing alcohol from your blood. An enzyme called alcohol dehydrogenase converts ethanol into acetaldehyde, a toxic byproduct and known carcinogen. A second enzyme then converts acetaldehyde into acetate, a relatively harmless substance your body can use for energy.
The liver processes alcohol at a roughly fixed rate, typically reducing BAC by about 0.015 per hour for most people. That means if you reach a BAC of 0.08, it takes around five to six hours for your body to fully clear the alcohol. No amount of coffee, water, food, or cold showers speeds up this process. Those things might make you feel more alert, but your BAC drops on its own timeline.
A secondary breakdown pathway kicks in when you drink more heavily. This system, which also processes certain medications, becomes more active in regular drinkers, which partly explains why frequent drinkers seem to “handle” more alcohol. Their livers are literally processing it through an additional channel. That said, the toxic byproducts still accumulate, and the long-term damage to the liver doesn’t change just because tolerance feels higher.
Legal BAC Limits Vary Widely
In the United States, the legal BAC limit for driving is 0.08 grams per deciliter for most adult drivers. The UK has one of the highest limits in Europe at 0.08 as well, though Scotland lowered its limit to 0.05. Most European countries set their standard limit at 0.05, including France, Germany, Spain, and Italy. Several countries go further: Sweden, Norway, and Poland set the limit at 0.02, and the Czech Republic, Hungary, Romania, and Slovakia enforce a strict zero-tolerance policy.
Many countries also impose stricter limits on new drivers and commercial vehicle operators. Germany, Italy, and Croatia require zero BAC for novice drivers, even though their standard limit is 0.05. These tiered systems reflect the fact that impairment begins well below the legal threshold. Measurable declines in visual tracking and divided attention start at a BAC of just 0.02.
When Drunk Becomes Dangerous
There’s a meaningful line between being drunk and being in medical danger, but it’s not always easy to spot from the outside. Alcohol poisoning occurs when BAC rises high enough to start suppressing basic life-support functions in the brainstem, particularly breathing.
The warning signs include confusion, vomiting, seizures, slow breathing (fewer than eight breaths per minute), irregular breathing with gaps of more than ten seconds between breaths, skin that looks blue, gray, or pale, abnormally low body temperature, and difficulty staying conscious. A person doesn’t need to show all of these symptoms for the situation to be serious. Someone who has passed out and can’t be woken up is in immediate danger.
Vomiting while unconscious is particularly risky because alcohol suppresses the gag reflex, making it possible to choke. The combination of slowed breathing and lowered body temperature can become fatal even if the person appeared “just really drunk” an hour earlier. BAC can also continue rising after someone stops drinking, because alcohol in the stomach and intestines is still being absorbed into the bloodstream.
Why the Same Amount Hits People Differently
Body weight is the most obvious factor. Alcohol distributes through body water, so a smaller person reaches a higher BAC from the same number of drinks. But weight is only part of the picture. Women generally have a higher proportion of body fat and less body water than men of the same weight, which means alcohol concentrates more in their bloodstream.
Food in the stomach slows absorption significantly. Drinking on an empty stomach allows alcohol to pass quickly into the small intestine, where it’s absorbed rapidly, producing a sharper and faster spike in BAC. Carbonation can also speed absorption, which is why champagne or mixed drinks with soda sometimes feel like they hit harder than the alcohol content alone would predict.
Genetic variation in the enzymes that break down alcohol plays a major role too. Some people, particularly those of East Asian descent, carry a version of the acetaldehyde-processing enzyme that works more slowly. This causes acetaldehyde to build up, producing facial flushing, nausea, and rapid heartbeat after relatively small amounts of alcohol. On the other end, people who produce more of the first breakdown enzyme may clear alcohol from the blood faster but generate more of the toxic byproduct in the process.
Tolerance from regular drinking also shifts the experience. Frequent drinkers develop both metabolic tolerance (the liver gets faster at processing alcohol) and functional tolerance (the brain adapts to operate under alcohol’s influence). Neither form of tolerance reduces the actual damage alcohol causes to organs. It simply raises the amount needed to feel the same subjective effects.