Synthetic cannabis addicts should smoke cannabis as it is the ''lesser of two evils'', says Dunedin Community Alcohol and Drug Services clinician Mark Greco.
Mr Greco said he only promoted cannabis use to those who had smoked it before becoming addicted to synthetic cannabis.
''We are a treatment service. If someone wants to address their alcohol use, we wouldn't recommend they stop consuming alcohol because they can experience withdrawal symptoms and those withdrawal symptoms can be very difficult for that person. We would recommend they drink to a controlled level and not to a level of intoxication.''
Cannabis was a partial agonist and synthetic cannabis was a full agonist, he said.
An agonist is a chemical that binds to a cell receptor and triggers a response. A partial agonist has partial efficacy and a full agonist has full efficacy.
The ingredients and effects of cannabis were well researched but the ingredients and effects of synthetic cannabis were ''pretty much unknown''.
''Cannabis has more of a spiritual cultural background to it. People listen to music and they know what they're in for. It's not about getting completely off your face.''
Home base detox service nurse Erin Watts said the Dunedin service had a Southern District Health Board contract to help people detoxify from drugs like synthetic cannabis and the advice to use a ''less harmful'' substance was reasonable.
''We come at things from a harm-reduction perspective, rather than what's legal and not legal. In an ideal world, no-one would use drugs but we don't live in an ideal world.''
In the Netherlands, where cannabis was legal, there were no problems with synthetic cannabis use, she said.
There were fewer cannabis-related problems in the Netherlands than in countries where cannabis was illegal, she said.
''It's an interesting discussion and I think as a country it's one we need to have.''