The Drug Foundation is concerned that teenagers younger than 18 are getting high on legal synthetic cannabis.
There have been reports of school children smoking the drug known as Kronic which can only legally be sold to adults.
Drug Foundation executive director Ross Bell says it's a big worry that people do not know exactly what is in the product and is scathing of the manufacturers for not being transparent about the drug's ingredients, when it is so widely available.
Mr Bell says New Zealand drug laws are obsolete, and while the Government banned the previously legal party drug BZP in 2008, products such as Kronic remain uncontrolled.
Commission calls for better controls
The Law Commission says herbal highs need to be better controlled, to prevent them being marketed and commercialised to young people.
The commission is looking at the use and supply of illegal drugs, as well as legal highs, in a review of the Misuse of Drugs Act.
Deputy president Warren Young says new substances can be distributed to young people without any controls.
Mr Young suggests the introduction of a regulatory agency such as the Environmental Risk Management Authority to set conditions on the sale and supply of herbal highs.
The commission's final report on the review is due in April next year.