Ethanol is the chemical compound that causes intoxication when a person consumes alcoholic beverages. This clear, colorless liquid is the psychoactive substance found in drinks like beer, wine, and spirits, and it acts as a central nervous system depressant. The process of getting drunk is a direct result of how the body absorbs and processes this molecule. Understanding the effects of ethanol requires looking closely at its source, its journey through the body, and how individual differences change the experience.
Ethanol: The Alcohol We Drink
Ethanol, also known as ethyl alcohol or grain alcohol, is the only type of alcohol intended for human consumption. It is naturally produced through fermentation, a metabolic process where yeast converts sugars found in grains, fruits, or other plant matter into ethanol and carbon dioxide. When people refer to “alcohol” in a drinking context, they are referring to this compound.
Ethanol is the main component, along with water, in most alcoholic beverages. While the alcoholic beverage industry uses fermentation-derived ethanol, the compound is also used widely as a solvent in everything from personal care products to fuels. The chemical structure of ethanol makes it soluble in both water and organic compounds, which allows it to move easily throughout the body.
The Journey to Intoxication
The intoxicating effect begins immediately after ethanol is ingested, as it is rapidly absorbed into the bloodstream primarily through the stomach and small intestine. Once in the blood, ethanol is highly water-soluble and quickly diffuses throughout the body, including across the blood-brain barrier. This allows it to reach the central nervous system (CNS), where it begins to exert its effects.
Ethanol functions as a CNS depressant, meaning it decreases the electrical activity of neurons in the brain. It interferes with neurotransmitters by enhancing the effects of gamma-aminobutyric acid (GABA), which is an inhibitory neurotransmitter. This action slows down brain activity, leading to the characteristic effects of intoxication such as slurred speech, impaired judgment, delayed reaction time, and loss of coordination. The liver metabolizes the vast majority (90% or more) of the ethanol in the body, converting it first into acetaldehyde and then into less active compounds.
Why Intoxication Varies Between People
The level of intoxication for a given amount of ethanol can vary significantly among individuals due to several physiological and situational factors. Body weight plays a substantial role, as a larger person has a greater volume of distribution to dilute the alcohol, generally resulting in a lower Blood Alcohol Concentration (BAC). Body composition is also a factor because alcohol is more soluble in water-rich muscle tissue than in fat tissue.
Gender influences intoxication because women tend to experience the effects more quickly and for a longer duration than men. This difference is partly attributed to women generally having less body water and lower levels of alcohol dehydrogenase, an enzyme that metabolizes alcohol in the stomach and liver. The rate of consumption and the presence of food in the stomach also alter the process; drinking quickly overwhelms the body’s ability to metabolize the alcohol, while eating beforehand slows the absorption rate into the bloodstream.
The Difference Between Alcohols
Understanding the chemical name “ethanol” highlights the difference between the drinkable compound and other toxic alcohols. Methanol (methyl alcohol) and isopropanol (isopropyl alcohol or rubbing alcohol) are two alcohols structurally similar to ethanol but are not safe for consumption. These substances are used in industrial products like antifreeze and disinfectants.
Methanol is hazardous because the body metabolizes it into formaldehyde and then formic acid, which can cause blindness, severe illness, and death even in small amounts. Isopropanol is metabolized into acetone and is about twice as toxic as ethanol, leading to severe gastrointestinal damage and respiratory depression. Ethanol is the only alcohol intended for human consumption, and confusing it with these other alcohols can have fatal consequences.