Drunkenness, or acute alcohol intoxication, is the temporary state resulting from the presence of ethanol in the bloodstream, which affects the central nervous system. This condition begins when the body absorbs alcohol faster than it can be metabolized and eliminated. The duration of this intoxicated state is highly variable and depends on a complex interplay of personal physiology and the body’s fixed metabolic rate. The time it takes for a person to return to sobriety is determined by how high the Blood Alcohol Concentration (BAC) reaches and the constant speed at which the body processes alcohol.
The Body’s Alcohol Elimination Mechanism
The primary process for removing alcohol from the body occurs in the liver, where specific enzymes break down the ethanol molecule. This breakdown begins with the enzyme Alcohol Dehydrogenase (ADH), which converts ethanol into a highly toxic compound called acetaldehyde. Because ADH becomes saturated even at relatively low alcohol concentrations, the rate of elimination remains nearly constant, a process known as zero-order kinetics.
Acetaldehyde is then rapidly converted into harmless acetate by the enzyme Aldehyde Dehydrogenase (ALDH). This acetate is then broken down into carbon dioxide and water, which the body can easily excrete. The liver’s fixed processing capacity means that no amount of coffee, cold showers, or other common remedies can speed up the rate of alcohol elimination.
The body metabolizes alcohol at a steady, predictable rate, regardless of the concentration in the blood. This metabolic rate averages about 0.015 grams per deciliter (g/dL) of BAC per hour in most individuals. Approximately 90% of the alcohol is eliminated through this metabolic pathway, with the remaining 5% to 10% excreted unchanged via breath, urine, and sweat.
Individual Factors Determining Peak Intoxication
The duration of drunkenness is directly tied to the peak Blood Alcohol Concentration (BAC) reached, which is heavily influenced by several individual factors. A person’s body size and composition play a significant role because alcohol is water-soluble and distributes itself throughout the body’s total water content. Individuals with a lower body weight and less overall water volume will have a higher BAC than a heavier person after consuming the same amount of alcohol, leading to a longer period of intoxication.
Biological sex also affects peak BAC, as women generally have a lower percentage of body water and lower levels of the enzyme ADH in the stomach compared to men. These differences mean that women typically absorb a greater proportion of alcohol directly into the bloodstream, resulting in a higher peak BAC from the same number of drinks.
Eating before or while drinking delays the passage of alcohol into the small intestine, the site of most rapid absorption. This delayed absorption results in a lower peak BAC, thereby shortening the overall duration of the intoxication period. Genetic variations in the efficiency of the ADH and ALDH enzymes also exist, which can cause significant differences in how quickly an individual processes alcohol.
The Stages and Duration of Impairment
The timeline of drunkenness moves through three general phases: absorption, peak, and elimination. The absorption phase, during which the BAC is rising, typically takes about 30 to 90 minutes after the last drink, especially if the stomach is empty. Once the peak BAC is reached, the body enters the elimination phase, where the constant metabolic rate slowly reduces the alcohol concentration.
The constant elimination rate means that a person with a BAC of 0.08%—the common legal limit for impairment—would need roughly five and a half hours for their BAC to return to 0.00%. The feeling of subjective drunkenness often fades before the alcohol is fully cleared from the system, which is a key distinction regarding impairment. Impairment can last significantly longer than the feeling of euphoria or visible signs of intoxication, as measurable effects on judgment and reaction time begin at BAC levels as low as 0.02%.
A person may feel sober enough to function, but their cognitive and motor skills remain objectively compromised until the BAC approaches zero. The legal definition of intoxication in many places is a BAC of 0.08% or higher, a level that causes significant impairment in balance, speech, and coordination.