Nearly 390,000 Kiwis are illegal drug users - and if tax was paid on the associated trafficking, the Government would pull in at least $245 million a year.
The New Zealand Drug Harm Index has been updated for the first time since 2008 and has estimated the annual social cost of drug use at $33,800 a year per dependent user and $2300 per casual user.
The Ministry of Health-commissioned research draws on official information to provide insights into the world of illegal drugs, including how much tax traffickers would be paying, and the large profit margins criminals make. Drugs were ranked according to harm per user, using a survey of health experts and detailed information on health, enforcement and family and wider society costs.
Synthetic cannabis was found to be as harmful as cocaine and much worse than other drugs such as ecstasy, LSD and natural cannabis. Alcohol and tobacco were not included. Methamphetamine was ranked as the most harmful drug for dependent users - those whose drug use was weekly or more frequent, and that resulted in self-reported harms.
Health officials are reviewing how severely people are dealt with for possession of illegal drugs or drug utensils.