Australians are underestimating the danger of popular sleeping pills and sedatives "at their peril", as a record 142 people die every month in accidental drug overdoses, a major new report warns.

Annual drug deaths almost doubled in the decade to 2016, a period that claimed 13,471 lives through unintentional overdose and saw drug deaths overtake the road toll.

Legal pharmaceutical painkillers are the leading killer, but most people are dying with a combination of substances in their system, including alcohol, heroin, amphetamines and synthetic cannabis.

One dangerous combination is prescription painkillers, sleeping tablets and alcohol.

The Penington Institute, which published the overdose report, warned that benzodiazepines – sleeping and anxiety pills common in Australian homes – were now contributing to hundreds of deaths each year.