A landmark study of WA leavers has uncovered the extent of binge drinking and reckless behaviour during schoolies celebrations.
It shows more than half had more than 11 standard drinks a day and many had consequences ranging from blackouts and injuries to unwanted sex and arrest.
The State Government launches a campaign today warning parents of the effects of alcohol on developing brains with the message that no alcohol is best for under-18s.
The survey of leavers at Rottnest in 2009 shows 87 per cent admitted to more than four drinks in a day.
Researcher Tina Lam, from Curtin University's National Drug Research Institute, said the results showed many leavers went intending to drink at saturation level.
Though her study was based on Rottnest, there was no reason to think risky drinking did not apply to many of the 10,000 students on leavers each year.
In the aftermath, two-thirds reported hangovers, 41 per cent said they had an accident or injury, 58 per cent had blackouts and 15 per cent had sex they were "not happy about" at the time.
Dr Lam said a positive finding was that students whose parents would not approve of them drinking excessively tended to drink less.
NDRI researcher Steve Allsop said the rates of drinking were a concern but the results showed teenagers listened to their parents.
Mental Health Minister Helen Morton said other new figures showed more than a third of WA teenagers who had alcohol were consuming at risky levels.
The 2011 Australian school students alcohol and drugs survey showed that in 12 to 17-year-olds who said they drank alcohol in the past week, risky levels increased from 20.9 per cent in 1993 to 36.2 per cent last year.
"Of those surveyed, fewer young people are choosing to drink but those who drink are doing so at increasingly riskier levels," she said.
"A child's brain develops until their early 20s and we need to discourage them from starting to drink and drinking harmfully for as long as we can."
The Alcohol Think Again campaign will be helped by the Telethon Institute for Child Health Research and the McCusker Centre for Action on Alcohol and Youth.
WA Commissioner for Children and Young People Michelle Scott said her talks with teenagers showed parents could influence drinking positively or negatively.
Contact the Parent Drug Information Service on 9442 5050 or country toll-free 1800 198024.