The Government has passed legislation which enables district councils to restrict sales of legal highs but not ban them.
The legislation has been criticised for being toothless, but the Government is refusing to budge, saying banning legal highs would create an illegal underground.
The father said his son started smoking cannabis at 14, then got hooked on legal highs when he was 17, about two years ago. The teen turned into a "monster", with psychosis, wild mood swings, insomnia and a propensity for sudden anger and violence.
"This stuff is ... destroying our youth and should be banned. The Government says it can't be banned, but individual products can be if they are shown to cause harm," he said.
The boy had started smoking synthetic cannabis because he thought it would be better than cannabis - because it was legal.
"Before taking synthetics he was into his rugby and league and surfing ... all normal, fun-loving teenage boy stuff ... he'd always been a bit highly strung to be honest, but legal highs took him down a completely mad road. First there was the mood swings, and psychosis and total anger, for seemingly nothing."
The 19 year-old had also contracted shingles from the stress of his situation. He managed to kick legal highs about four months ago but still got depressed, slept badly and suffered mood swings.
"If people report adverse effects to the National Poisons Centre they can use them as evidence to get individual products banned. I urge people to report effects," the father said.
The concerned parent is involved in the "Ban Synthetic Cannabinoids Whangarei" Facebook group which is holding another rally on Saturday.
The rally will be held outside the Brew Shop, in Vine St, from 1pm.
The group will be gathering more signatures for its petition against the sale and distribution of legal synthetic cannabinoid highs throughout the country.
The council plans to restrict where legal highs can be sold in the city to Lower Cameron St, Clyde St and Albert St and will only allow them to be sold between 10am and 2pm and 6pm and 8pm.
Parliament introduced the Psychoactive Substances Act last year, which gives local authorities the right to develop a locally approved products policy that can determine where products can be sold. When submissions on the council's plan closed on April 11, it had received more than 70 submissions.
From the submissions received, suggestions to enhance the policy have included boosting community safety activities within the proposed zone such as City Safe and CCTV, changing the hours of availability recommended to the Psychoactive Substances Regulatory Authority and amending the proposed zone.
These will be considered by councillors in coming weeks.
