Are You Still Drunk When Hungover: Myths and Facts

Many assume that once a hangover sets in, all alcohol from the night before has left their system. However, lingering effects of alcohol metabolism and dehydration can create confusion about whether someone is still intoxicated or simply dealing with a rough morning. This distinction is important, especially when making decisions like driving or working.

Understanding how long alcohol stays in the body and the difference between being hungover and still drunk helps clarify misconceptions.

Metabolism And Clearance Of Alcohol

Once alcohol enters the bloodstream, the body begins breaking it down. The liver is responsible for most alcohol metabolism, primarily through two enzymes: alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). ADH converts ethanol into acetaldehyde, a toxic intermediate that contributes to alcohol’s unpleasant effects. ALDH then rapidly processes acetaldehyde into acetate, which is further broken down into water and carbon dioxide for excretion. This metabolic process operates at a fixed rate, meaning that external factors like hydration, caffeine, or physical activity do not significantly speed up alcohol clearance.

On average, the body metabolizes alcohol at a rate of about 0.015 grams per deciliter (g/dL) per hour—roughly one standard drink per hour. However, individual variations in metabolism can alter this rate. Genetic differences, liver health, age, sex, and body composition all influence how quickly alcohol is processed. For instance, some genetic variants slow acetaldehyde breakdown, prolonging exposure to its toxic effects. Those with liver disease may also metabolize alcohol more slowly, extending intoxication.

At higher concentrations, alcohol follows zero-order kinetics, meaning the body processes a constant amount per unit of time rather than a percentage of the remaining alcohol. This explains why heavy drinking can lead to prolonged intoxication, as the liver can only metabolize a finite amount at a time. Even when blood alcohol concentration (BAC) falls below the legal limit for driving (0.08% in the U.S.), cognitive and motor impairments can persist, especially after excessive drinking.

Physiological Changes During Hangover

As BAC declines, the body experiences physiological disruptions that contribute to hangover symptoms. One major effect is dehydration, caused by alcohol’s inhibition of vasopressin, an antidiuretic hormone that regulates fluid balance. With reduced vasopressin activity, the kidneys excrete more water, leading to dehydration. This fluid loss contributes to dry mouth, dizziness, and headaches as diminished blood volume affects oxygen delivery to tissues, particularly in the brain.

Alcohol-induced inflammation also plays a role in hangover severity. As ethanol is broken down, acetaldehyde triggers oxidative stress and inflammatory responses. Studies in Alcohol Research: Current Reviews show that elevated cytokine levels, particularly interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), correlate with hangover intensity. These inflammatory molecules disrupt neurotransmitter function, contributing to fatigue, cognitive fog, and mood disturbances. Additionally, alcohol disrupts the gut microbiome, increasing intestinal permeability and allowing endotoxins into the bloodstream, further amplifying inflammation.

Neurotransmitter imbalances add to post-intoxication discomfort. Alcohol enhances gamma-aminobutyric acid (GABA) activity while suppressing glutamate signaling, creating sedative effects. As alcohol clears, the brain compensates by upregulating glutamate, leading to excitotoxic effects such as restlessness, anxiety, and difficulty concentrating. This rebound excitability is particularly noticeable in heavy drinkers, as their nervous system experiences temporary hyperactivity once alcohol’s depressant effects wear off.

Alcohol also affects blood sugar regulation. Ethanol inhibits gluconeogenesis—the process by which the liver generates glucose—resulting in transient hypoglycemia, especially in those who have not eaten adequately before or during drinking. Low blood sugar levels contribute to shakiness, weakness, and irritability, worsening the overall sense of malaise. This effect is particularly concerning for individuals with metabolic conditions like diabetes, where alcohol-induced hypoglycemia can pose serious health risks.

Differences Between Residual Intoxication And Hangover

Residual intoxication occurs when BAC remains elevated, meaning alcohol is still affecting the central nervous system. In this state, cognitive impairment, delayed reaction times, and diminished motor coordination persist, even if overt signs of drunkenness—such as slurred speech—have faded. This can create a false sense of sobriety, leading individuals to underestimate their impairment. Research in Traffic Injury Prevention indicates that even when BAC falls below legal limits, deficits in attention and executive function may persist for hours, increasing the risk of accidents.

A hangover, on the other hand, is the body’s response to alcohol withdrawal and its metabolic aftermath. Once BAC reaches zero, symptoms shift from intoxication to physiological stress. Headaches, nausea, fatigue, and irritability become more pronounced as neurotransmitter imbalances, dehydration, and inflammation take hold. Unlike residual intoxication, where impairment is directly tied to alcohol presence, a hangover occurs regardless of measurable BAC. This explains why someone can feel significantly worse the morning after drinking despite no longer being legally intoxicated.

The overlap between these states can create confusion, particularly when determining whether it is safe to engage in tasks requiring full cognitive function, such as driving. Since alcohol is metabolized at a fixed rate, those who drink heavily late into the night may still have a BAC above zero upon waking, prolonging residual intoxication. A study in Addiction Biology found that individuals who reached a BAC of 0.12% or higher often exhibited measurable impairments in memory recall and motor function up to 12 hours later, even after subjective feelings of drunkenness had faded. This delayed clearance is especially problematic for shift workers, medical professionals, or anyone required to perform tasks demanding precision and alertness shortly after drinking.

Common Myths About Being Drunk While Hungover

Many believe that if they wake up feeling terrible after drinking, they must be completely sober and merely experiencing aftereffects. This assumption leads to risky decisions, such as driving, under the false impression that the body has fully processed the alcohol. In reality, impairment can persist even when someone no longer feels intoxicated, and subjective perception is not always a reliable measure of sobriety. Studies show that individuals can still experience reduced cognitive function and motor coordination hours after their last drink, even if they feel alert.

Another common misconception is that certain remedies, such as cold showers, strong coffee, or greasy breakfasts, can speed up alcohol elimination. While these methods may provide a temporary sense of wakefulness, they do not accelerate alcohol metabolism, which remains constant regardless of external interventions. Caffeine, for example, can mask fatigue and create a false sense of alertness, but it does nothing to improve reaction times or reduce alcohol’s lingering effects. This misplaced confidence can be dangerous, as individuals may believe they are fit for high-risk activities when their reflexes and judgment are still compromised.