Symptoms of Intoxication BAC (Blood Alcohol Content) (mg/dL)

In the human body, ethanol is first oxidized to acetaldehyde, and then to acetic acid. The first step is catalyzed by the enzyme alcohol dehydrogenate, and the second by acetaldehyde dehydrogenate. Some individuals have less effective forms of one or both of these enzymes and therefore experience more severe symptoms from ethanol consumption than others. Conversely, those who have an acquired ethanol tolerance have a greater quantity of these enzymes, and can METAbolize ethanol more rapidly.

 50 Euphoria, talkativeness, relaxation
 100 Central nervous system depression, impaired motor and sensory function,
 impaired cognition
 140   Decreased blood flow to brain
 300   Stupefaction, possible unconsciousness
 400   Possible death
 550   Death highly likely

The amount of ethanol in the body is typically quantified by blood alcohol content (BAC), the milligrams of ethanol per 100 milliliters of blood. The table shown above summarizes the usual symptoms of ethanol concentration. Small doses of ethanol generally produce euphoria and relaxation; people experiencing these symptoms tend to become talkative and less inhibited, and may exhibit poor judgment. At higher dosages (BAC > 0.10), ethanol acts as a central nervous system depressant, increasing at progressively higher doses, impaired sensory and motor function, slowed cognition, stupefaction, unconsciousness, and possibly death at extremely high levels.

The initial product of ethanol Metabolism, acetaldehyde, is actually more toxic than ethanol itself. The body can quickly detoxify some acetaldehyde by reaction with glutathione and similar thiol-containing biomolecules. When acetaldehyde is produced beyond the capacity of the body's glutathione supply to detoxify it, it accumulates in the bloodstream until it can be oxidized to acetic acid. The common headache, nausea, and malaise associated with an alcohol hangover stem from a combination of dehydration and acetaldehyde poisoning. Many health conditions associated with chronic ethanol abuse, including liver cirrhosis, alcoholism, and some forms of cancer, have been linked to acetaldehyde. Some medications, including paracetamol (acetaminophen), as well as exposure to organochlorides, can deplete the body's glutathione supply, enhancing both the acute and long-term risks of even moderate ethanol consumption.