The drug which causes the most widespread harm in New Zealand isn't methamphetamine or synthetic cannabis. It's alcohol.

That's according to new research by the University of Otago Christchurch, published in the Journal of Psychopharmacology.

Kiwi researchers found that, when separately considering harm to those who use it and harm to others, alcohol was the most harmful drug for the total population.

Alcohol's position at the top of the ranked had it ahead of methamphetamine, synthetic cannabinoids and tobacco.

While other global studies have ranked harm in a general population, it's believed this is the first to evaluate and rank psychoactive drug harm among society and young people in New Zealand.

Aotearoa's two most widely used legal drugs, alcohol and tobacco, were found to cause the first and fourth-largest amount of harm overall.

Study co-author, Dr Rose Crossin​, from Otago's Department of Population Health, says the findings will 'surprise some” who may have assumed other illegal drugs caused more harm than 'our most widely used legal drug”.

Crossin says it might 'challenge” people to learn this, but alcohol isn't the most harmful because it's the most widely used.

'It's rated the most harmful because of its association with a huge number of diseases, cancers, psychological disorders and other medical conditions,” she says.

Alcohol also causes more harm to others than to those who use it, including families, friends, communities and wider society, she says.

As an example, it's associated with foetal alcohol spectrum disorder, which negatively affects a person's life, education and employment prospects.

Two expert panels were established to provide data for the study, using knowledge based on their diverse expertise in medicine, psychology, justice, community services and harm reduction.

Two facilitated workshops identified separate rankings of harm, first for the total population, and then for youth aged 12-17​.

Alcohol ranked the highest for both harm to self, and harm to others. Photo: University of Otago.

Overall, 23​ drugs – including alcohol and tobacco – were ranked.

Crossin says the findings demonstrate a need to improve resourcing for interventions which reduce harm, for those who need them.

Co-author Professor Joe Boden​ says the findings identify a mismatch between legal status and harm.

For example, they found a 'spread” of harmfulness among illegal Class A drugs – those carrying the harshest penalties for possession and supply/manufacture – with some causing a lot of harm, and others 'very little”.

'In some cases, the criminal penalties for using these drugs don't match the level of societal harm they actually cause,” says Boden.

People living with FASD, Māori, and health experts will make up a new group that will advise the Crown on how to better support people with the disorder and quell rates of FASD. Video: Stuff.

The authors say New Zealand's drug policies also cause harm.

'Our study has identified that a significant proportion of drug harm arises from the legal status of the drug, rather from the drug itself,” he says.

This included harms to the drug user, such as loss of employment and relationships, along with harms to others, including crime, and whānau.

'This suggests we need to reconsider our policy settings to reduce overall drug harm, and consider how best to support family, friends and communities – not just the actual individual using the drug,” says Boden.

NZ Drug Foundation executive director Sarah Helm​ says the research 'makes clear there's no relationship between legality and lower harm... We need to shift towards regulation of substances based on the actual harm they cause”.

The Ministry of Health and Te Whatu Ora have been approached for comment.

- Hannah Martin/Stuff.