Alcohol and Drugs
Sometimes the names are well-known: River Phoenix, Jim Morrison, Janis Joplin. All are reported to have died as a result of ingesting a fatal combination of alcohol and drugs. They're just three of the thousands of people each year who become ill, are injured, or die because of the interaction of alcohol and drugs in their bloodstreams.
We're not necessarily talking about illicit drugs here. Many prescription and non-prescription medications can also interact with alcohol, leading to increased risk of illness, injury or death. For example, it's estimated that alcohol-medication interactions may be a factor in at least 25% of all emergency room admissions.
Bibliography: "Alcohol and Drugs"