Children who use vapes face a much greater risk of progressing to cigarettes, research shows.
Generation Vape, a national research project into the growing rates of e-cigarette use among young people, surveyed more than 5100 teenagers.
It found 12-year-olds who had vaped were 29 times more likely to go on to try smoking than children the same age who had not.
Health experts say it's an important reminder of the need for governments to work together to enact and enforce vaping reforms.
The study, the first of its kind in Australia, used data collected in 2023.
Lead author Sam Egger said they found children aged 12-17 who had vaped were five times more likely to start smoking, with the rates escalating the younger the child started vaping.
"The younger a person started using vapes, the higher their increased risk that they would subsequently try smoking," he said.
Until recently, Australia was an international success story in minimising teen smoking, University of Sydney study supervisor Becky Freeman said.
Teenage ever-smoking rates dropped from 58 per cent in 1996, to 14 per cent in 2023.
Recent data suggested a possible increase in teenage smoking as vape use had exploded "and this latest study shows how real that threat is", Associate Professor Freeman said.
"Young people … have grown up seeing graphic health warnings on expensive cigarette packs and think smoking is unattractive and something from their parent's generation," she said.
"They view vaping as an entirely different behaviour to smoking and don't know that they are more likely to take up smoking if they vape."
Health experts welcomed the federal government's vaping reforms, which passed in June, but Public Health Association of Australia chief executive Terry Slevin said positive change won't happen overnight.
"We need to make sure that state and territory governments are harmonising their local legislation and enforcement with the federal reforms," he said.
"All levels of government will need to work together to protect young people."
Support is available for teenagers who vaped or smoke and had become addicted to nicotine, said research co-author Alecia Brooks.
"We anticipate that now restrictions on vaping are coming into place, any population-level impacts that e-cigarettes are having on smoking rates will become minimal, but we aren't entirely out of the vape haze yet," she said.
The study was published on Tuesday in the Australian and New Zealand Journal of Public Health.
People who need support should speak to their doctor or call Quit on 137 848.
