If someone asked you to bet on the drug that causes the most harm, which one would you pick?

Fentanyl, a drug 50 to 100 times more potent than morphine – so powerful, even, that it can cause an overdose in a single breath? Or crack cocaine, with nasty side effects that include paranoia, organ failure, seizure, and death?

The correct answer is neither of the above. According to a paper recently published in the Journal of Psychopharmacology, the most harmful drug is alcohol.

A team of 25 experts came to this conclusion after scoring 22 drugs on 16 criteria, using a scale of 0 to 100. In this case, 0 represented "no harm" and 100 signified "most harm". The analysis was based on a similar study conducted in the UK in 2010 but had been adapted for an Australian context.

As with the original study, nine criteria were based on harms to the drug user. Think: drug-specific mortality, dependence, drug-related impairment of mental functioning, and loss of relationships. While the remaining seven were based on harms to others. For example, injury, crime, economic cost, and community. The criteria were then weighted to produce a final score.

The analysis found that the drug most harmful to the individual was fentanyl, with a part score of 50 (out of 50). The runner-up was heroin (45), followed by alcohol (41), crystal meth (24), and tobacco, or cigarettes (14).

But when harm to others was factored in, the list changed. Alcohol came top (combined score 77), followed by crystal meth (66), heroin (58), fentanyl (51), and tobacco (32). Straddling the bottom was kava (combined score 3), e-cigs (3), LSD and mushrooms (5), antipsychotics (7), and ecstasy (7).

Interestingly, both UK and Australian studies found alcohol to be the most harmful drug. In this study, it scored especially high on the criteria of economic cost, family adversity, injury, drug-related morbidity, and drug-specific morbidity.

Yet, there were differences in the runner-up – in Britain, heroin scored second place, whereas, in Australia, crystal meth did. The criteria most relevant to crystal meth, the researchers concluded, were crime, injury, loss of relationships, loss of tangibles, drug-specific morbidity, and drug-related morbidity.

According to the paper, Australia has the highest prevalence of methamphetamine use in the world, with death rates from the drug doubling between 2009 and 2015. In contrast, its use in Europe is historically low – with the strange exception of Slovakia and the Czech Republic. (A 2015 report found that 95 percent of Europeans treated for meth dependency were in one of those two countries.)

Their initial analysis was followed up by a supplementary analysis that scaled the harm to user score according to drug prevalence. Alcohol retained its top position but noticeably cannabis swooped in from 13th to 4th place, an interesting observation, the researchers say, given the current legalization debate.