A record number of Australians are addicted to amphetamines like ice, with half of those seeking help for addiction using the drug, according to a report by one of Australia's largest drug rehabilitation organisations.

Odyssey House, in its annual report, has reported a 53 per cent jump in the number of people admitting to using amphetamine-type stimulants.

The organisation's chief executive, Julie Babineau, said ice is very addictive and more potent than other drugs.

"We see that heroin and opiates has really gone down and, I think, that that's what the people out there are looking for — the purity," she said.

"And they're looking for the cost as well and the availability."

The report also shows a drop of 45 per cent in heroin and prescription opioid users on the previous year.

Ms Babineau said the growth in ice addiction means there is a need for increased and longer-term government funding as well as more facilities, trained staff and support for addicts who may not know what they are doing.

"They get in trouble, and once you get in trouble, there's the trifecta," she said.

"You're addicted, you get in trouble, you get into crime and then … you go to prison or you become homeless.

"More and more of these people will be needing residential rehab and any help with their addiction to be able to get back on track."

Ms Babineau said two thirds of drug users are now over 30, with users reporting their first intoxication at a much younger age than over a decade ago.