You've probably met one: someone swaying gently, breath strong enough to stun a mosquito, and yet — somehow — completely convinced they could move a mountain. It's a familiar enough sight, and it raises an obvious question. What is it about alcohol that turns a perfectly sensible person into that? What's the actual mechanism behind being drunk?
Before the science, one small fact worth holding onto: the word "intoxicated" literally means "poisoned inside." That's not poetry. It's a fairly accurate description of what's going on.
Meet ethanol, the culprit
The main character is a small molecule called ethanol. It's produced when yeast ferments the sugars in plants — the same process whether the brew ends up as beer, wine, or spirits. From barley you get beer; from grapes, wine; from potatoes or grain, vodka. Each drink carries its own concentration and flavour, but the molecule doing all the work is always the same one. Ethanol is small, it dissolves easily in water, and it can slip through the walls of your gut and into your blood without much resistance at all.
It's really about how fast it reaches your blood
How drunk you feel depends on a whole list of things: your age, your body size, your metabolism, your genetics, the strength of the drink, and whether your stomach was empty or full. But all of those funnel into one number that matters most — the concentration of alcohol in your blood, and how quickly it gets there. Once ethanol is in the bloodstream, it has a free pass to almost every organ in the body. So the question becomes: where does it go, and what does it do when it arrives?
The stomach
Your stomach is the first gatekeeper. If there's food in it, the alcohol gets mixed and diluted, and its absorption into the blood is slowed. If the stomach is empty, there's nothing to hold it back, and blood alcohol can climb sharply — which is why drinking on an empty stomach hits so much harder, so much faster.
The liver
Next, the blood carries the alcohol to the liver, the body's chemical processing plant. The liver works to break ethanol down, eventually converting it into water and carbon dioxide. But it can only manage a limited amount per hour — roughly one standard drink's worth. Keep drinking faster than the liver can keep up, and alcohol accumulates in the blood, which is exactly when the stumbling and the slurring begin. Push the liver hard enough, over years, and the damage can scar it permanently — a condition called cirrhosis.
The brain
When ethanol reaches the brain, it changes how signalling chemicals behave. At first it nudges up the feel-good messengers, dopamine and serotonin, which is why the early stages of drinking can feel happy and carefree. But alcohol is, at heart, a depressant: as the dose rises, it slows the brain's activity down, which is what brings the slurred speech, the blurred vision, the poor judgement and the loss of coordination. The famous confidence is really the part of the brain that usually says "maybe don't" switching off.
The kidneys
Now a part most people get backwards. Your body makes a hormone called ADH — anti-diuretic hormone — whose normal job is to tell the kidneys to hold on to water. Alcohol suppresses that hormone, so the kidneys stop conserving water and let more of it escape into your bladder. That's why a drink or two sends you running to the toilet, and why a heavy night can leave you badly dehydrated by morning.
The lungs
Finally, your lungs get involved. A small share of the alcohol — around five percent — leaves the body in your breath. That's why you can smell it on someone's breath, and it's the very principle that lets a breathalyser detect how much a driver has had.
A gentle warning
The speed of all this varies enormously from person to person. Age, body weight, genetics, sex, and even how tired or well-fed you are all shift the dial. And that's worth respecting, because alcohol can do serious and lasting harm when it's overdone — and in the worst cases it can be fatal, from accidents, from alcohol poisoning, or from long-term damage.
So choose your potion wisely, and know your own limit rather than the one printed on the bottle. Knowing what's happening inside your body is the first step to making smarter choices about it. The mind is quite capable of feeling curious all on its own — no alcohol required.