Alcohol intoxication, also known in overdose as alcohol poisoning, commonly described as drunkenness or inebriation, is the negative behavior and physical effects caused by a recent consumption of alcohol. In addition to the toxicity of ethanol, the main psychoactive component of alcoholic beverages, other physiological symptoms may arise from the activity of acetaldehyde, a metabolite of alcohol. These effects may not arise until hours after ingestion and may contribute to the condition colloquially known as a hangover.

Symptoms of intoxication at lower doses may include mild sedation and poor coordination. At higher doses, there may be slurred speech, trouble walking, and vomiting. Extreme doses may result in a respiratory depression, coma, or death. Complications may include seizures, aspiration pneumonia, injuries including suicide, and low blood sugar. Alcohol intoxication can lead to alcohol-related crime with perpetrators more likely to be intoxicated than victims.

Alcohol intoxication typically begins after two or more alcoholic drinks. Risk factors include a social situation where heavy drinking is common and a person having an impulsive personality. Diagnosis is usually based on the history of events and physical examination. Verification of events by witnesses may be useful. Legally, alcohol intoxication is often defined as a blood alcohol concentration (BAC) of greater than 5.4–17.4 mmol/L (25–80 mg/dL or 0.025–0.080%). This can be measured by blood or breath testing. Alcohol is broken down in the human body at a rate of about 3.3 mmol/L (15 mg/dL) per hour, depending on an individual's metabolic rate (metabolism).

Management of alcohol intoxication involves supportive care. Typically this includes putting the person in the recovery position, keeping the person warm, and making sure breathing is sufficient. Gastric lavage and activated charcoal have not been found to be useful. Repeated assessments may be required to rule out other potential causes of a person's symptoms.

Acute intoxication has been documented throughout history, and alcohol remains one of the world's most widespread recreational drugs. Some religions consider alcohol intoxication to be a sin.