This article reviews the behavioral and medical consequences of alcohol. Alcohol, more than any other drug, is a common finding in toxicology and forensic medicine and proper understanding of its effects is critical to the interpretation of forensic evidence. Acute intoxication results in increased risk for and is a contributing factor in a variety of injuries including driving, fall‐downs, bicycling, thermal, water sport, aircraft operation, and suicide. Intoxication may also affect the outcome of certain types of injuries and shortens life. Chronic alcohol abuse also increases risk and injuries of the nature often encountered in forensic evaluations because of frequent intoxication to high blood‐alcohol concentrations. Physiological changes, such as in bone density and liver pathology can affect injury severity, behavior, pharmacokinetics, and life span.