How Alcohol Affects the Body

Alcohol — ethanol — is the most widely consumed psychoactive substance in the world, woven into social customs across cultures for thousands of years. It is also, by objective measure of harm, one of the most damaging substances in use: responsible for approximately 95,000 deaths per year in the United States and 3 million globally, it causes liver disease, cardiovascular damage, neurological dysfunction, cancer, and devastating social consequences. Understanding what alcohol does to the body — the neurochemistry behind intoxication, the organ damage from chronic use, and what "safe" drinking means in practice — informs both personal decisions and societal approaches to a major public health challenge.

The Chemistry Of Alcohol: Ethanol In The Body

Ethanol (CH3CH2OH) is a small, lipid-soluble molecule that is rapidly absorbed primarily from the small intestine (approximately 80%) and the stomach (approximately 20%). Unlike most nutrients, it does not require enzymatic digestion before absorption.

Once absorbed, ethanol enters the portal circulation and reaches the liver, where it is metabolized: