The National Poisons Centre says long term use of synthetic cannabis could cause a range of serious mental health problems.
The centre says the number of calls it is getting suggest a link between constant use of cannabis products like Kronic and thoughts of suicide as well as anger and paranoia.
The Government banned all existing synthetic drugs in 2011, but new products are continually emerging and available before being caught and banned.
Leo Schep, a toxicologist with the poisons centre, says the effects of long-term use are only just starting to surface and withdrawal issues are also serious.
New legislation being introduced this year will require manufacturers to prove that their products are safe before they can be sold.