Study highlights role of drugs in alcohol poisoning and blackout events

Reviewed by Kate Anderton, B.Sc. (Editor)Oct 9 2019

Only one in five non-fatal alcohol overdoses results from use of alcohol alone, according to a study of patients in a large addiction treatment facility, with most alcohol overdoses involving concomitant use of other drugs. Alcohol can interact with other drugs ─including marijuana, central nervous system depressants such as opioids, and stimulants such as cocaine ─in various ways, and using them together is known to increase the likelihood and severity of overdose.

Despite this, there is limited research examining the characteristics of alcohol overdose in the context of concomitant drug use. The new study, published in the journal Alcoholism: Clinical & Experimental Research, provides a clearer understanding of role of other drug use and its impact on outcomes of alcohol overdose.

Researchers from Ann Arbor, Michigan, and Baltimore, Maryland analyzed data from over 600 adult patients attending a residential drug and alcohol rehabilitation center. The patients had completed a questionnaire on their experiences of alcohol overdose, defined broadly as alcohol poisoning, passing out, or blacking out resulting from excessive drinking.

Information on any drugs they had taken with alcohol before their most recent overdose, and on whether they were hospitalized as a result of the overdose, was also collected. Drug overdose events were reported separately, and cross-checked against the alcohol overdoses to ensure they did not represent the same events.

Nine out of ten patients reported having had at least one alcohol overdose in their lifetime. When considering their most recent alcohol overdose, 21% of patients reported using alcohol alone, and 79% reported concomitant drug use ─most commonly marijuana, followed by sedatives, prescription opioids, cocaine or crack, heroin, and other drugs.

Using statistical modelling, the research team was able to describe three classes of alcohol overdose: those with no or low drug involvement (use of at most one other drug, usually marijuana, besides alcohol), representing 61% of the most recent overdoses; moderate drug involvement (use of two to four other drugs), representing 33% of overdoses; and high drug involvement (six to eight other drugs), representing 6% of overdoses. Patients whose overdoses had high or moderate drug involvement were more often female, and younger, than those with no/low drug involvement, and were also more likely to be hospitalized as a result of their overdose.

The findings indicate that alcohol overdoses involving multiple other drugs are common and more severe than other overdoses. The researchers recommend that ongoing overdose prevention efforts should address the acute risks of alcohol ingestion with other drugs, to help curtail the national rise in alcohol-related overdoses.