Insomnia, vomiting, agitation and "strange thoughts" are the most common effects of synthetic cannabis, according to a newly published study.
The side-effects of using the product aren't well documented, but a just-published survey from Massey University sheds some light on what people feel after ingesting the synthetic high.
The data was collected in central Auckland between April 23 and May 7, 2014 when synthetic cannabis was still legal, and also looked into the effects of party pills.
It also asked about alcohol, cannabis, ecstasy and methamphetamine use.
Frequent legal high users were asked outside eight randomly selected licensed legal high stores to do the online survey.
Of the 105 who completed the survey, 54 percent were considered to be dependent on synthetic cannabis having admitting to using it daily.
There was an 80:20 split between respondents who used synthetic cannabinoids and party pill users, 27 percent of whom reported having suffered mental illness during their lifetimes.
The most common problems with synthetic cannabis were:
Users also reported skin problems, drowsiness, paranoia, weight loss, depression, shortness of breath, blurred vision and fainting.
The most common life problem from those who use synthetic cannabis was spending too much money (51 percent), with 29 percent saying they'd damaged a friendship or relationship.
Reduced work or study performance and arguing with others were the next most common at 21 percent.
Of those who responded to the survey, 17 percent said they couldn't remember the night before while 15 percent lost or quit their job.
Ten percent of the respondents were unemployed, and 11 percent were on a sickness benefit.
The study's authors say the fact a quarter of users reported suffering mental illness is concerning, given legal highs have been associated with inducing psychotic relapse and triggering new psychotic events.
However, they say their study has limitations insofar as it was not a representative sample of frequent legal high users in central Auckland or other parts of New Zealand.
"Central Auckland may be different from other parts of the country in important ways, including the concentration of legal high stores and other late night nightlife venues," they write.
The reported adverse effects of the products were also self-reported, and not supported by blood or urine tests.