Adrian Baxter, a drug and alcohol worker at the Winnunga Nimmityjah health service, said not only were younger people using ice but users became addicted quickly and reached extreme psychosis and paranoia that made the drug more difficult to deal with than others.

Micah Hill, 39, knows the destructive impact of ice, which brought him to multiple suicide attempts before he left Queensland to escape his addiction and try to turn his life around.

"You're not yourself when you're on ice," he said. "You're like your evil twin."

Mr Hill says he began taking speed, the less pure form, at 17 before he started cooking ice himself.

"At first it's good but then after a while it's like a burden," he said. "You've got to have it every day, regardless who you hurt, who you rob. You don't care."

So deep was his addiction he was using between $2000 and $2500 worth each week. In one two-month stint he didn't sleep or eat and his weight dropped from 110 to 59 kilograms, landing him in intensive care.

Getting off the drug was so difficult "you wouldn't wish it on your worst enemy", he says. But he has been clean for more than two years. "A lot of people say you can't break an addiction. I don't believe that."

Matthew Wilson, 40, of Sutton, said the key was cutting off the supply and addicts should have somewhere to "voluntarily lock yourself up for a fortnight".

"It's easy to break an addiction if you can't get something," he said. "But it's admitting that you've got the addiction first. It's admitting it to yourself, admitting it to your family."

Mr Wilson says ice creates a "fake reality", with users getting a skewed idea of what's important. "It's hard for families to understand because they see this erratic behaviour and there's no explanation for it," he said.

Mr Wilson has been off ice since late last year, but a conviction for drug possession has affected his ability to get a job despite having qualifications, including a degree.

"I knew I had to stop because if I didn't care about myself, no one else was going to," he said.

He urges more education and a harm-minimisation approach. And his message to users is: "You have to be careful with the people that you hurt on the way because not everybody's going to forgive you for it."

As a mother, Narelle King has been hit hard by the worst drugs of the past two decades.

Her oldest daughter died of a heroin overdose, leaving two young children that Ms King has brought up. More recently, her son got caught up in ice, she said.

Her son is Steve Freeman, who was in a coma in intensive care in April after being assaulted in prison.

Ms King judges ice, which causes uncontrollable mood swings in addicts, as the more dangerous of the two drugs.

Winnunga chief executive Julie Tongs says ice has presented challenges never before faced by the health service.

"Some days it's very chaotic here when we have got people in the waiting room that are affected by ice and are psychotic," she said in April.

Kathleen Orr, a senior trainer at drug treatment service Odyssey House in Victoria, told the group that the crystal form of ice now predominant was between 30 per cent and 80 per cent pure, whereas its predecessor, the powdered-form speed, was 10 to 20 per cent pure.

One quarter of users used the drug weekly. And though the first 14 days of detox were the most acute, its effects on mood, anger, memory, planning ability and problem-solving could last 18 months or more after detox, she said.