"The issue of when teens start drinking is a very important question."
Teenagers who drink only small amounts of alcohol have a significantly higher risk of abusing alcohol or engaging in risky sexual behaviour as young adults, research has found.
The research casts doubt on new national guidelines that suggest there is a low-risk level of drinking for under-18s.
It provides evidence for a move away from the harm-minimisation approach and raises questions about the apt legal minimum drinking age, experts say.
A team from Melbourne's Murdoch Children's Research Institute says its study, which has tracked 1520 young people's drinking habits over more than 10 years from mid-teens to mid-20s, shows there is no safe or sensible level of drinking for adolescents, in light of later likely events.
National Health and Medical Research Council guidelines define a low-risk level of drinking for adults as fewer than three standard drinks a day.
The research found teenagers, drinking at even this level, increased their chances of alcohol abuse, social or legal problems or alcohol-related high-risk sexual behaviour, 10 years down the track.
"The issue of when teens start drinking is a very important question," lead researcher, epidemiologist Elya Moore, said.
"Those who abstained from any alcohol in adolescence experienced fewer (bad) alcohol-related outcomes than those who drank at the recommended level.
"We found no evidence of a level that may have been safe," Dr Moore said.
The research, published in the Australian and New Zealand Journal of Public Health, found that by young adulthood, 27 per cent of men and 13 per cent of women met at least one of the criteria for alcohol abuse and risky sexual behaviour.
The research showed a clear trend: the more boys drank as teenagers, the more likely they were to develop alcohol-related problems as a young adult.
The trend was not as clear for girls.
Dr Moore said this could have been a failure of the research method, rather than evidence that girls were more able to drink at safe levels.
Official guidelines state that the safest option is not to drink alcohol under 18.
For those 15 to 17 they say "the safest option is to delay … drinking for as long as possible", and "if drinking does occur it should be at a low-risk level and in a safe environment".
The study found the chances of developing an alcohol disorder among low-risk drinkers were closer to that of risky drinkers than to that of non-drinkers.
Director of adolescent health research at the Royal Children's Hospital George Patton said he had expected that those with no evidence of excessive drinking patterns as teens would do well as adults.
"But we found, particularly for males, that those who start drinking early had very high rates of alcohol abuse and dependence, even if they had started (by) drinking sensibly," Professor Patton said.
"For some time, we have seen rising rates of alcohol abuse and binge drinking in the young adult and adolescent age range.
"One view was to teach adolescents to drink sensibly: the harm-minimisation approach. In the 1990s, the health education messages going out were based on that idea. This paper is significant because it looks at that question," he said.
Alcohol Education and Rehabilitation Foundation chairman Scott Wilson said the study suggested alcohol guidelines for under-18s should be made clearer: "Zero alcohol, full stop."