The survey, conducted in conjunction with media outlets including Fairfax Media at the end of last year in 18 countries, found many Australians who are drinking at seriously dangerous levels believe their drinking is "about average".

Public Health Association of Australia spokesman on alcohol Mike Daube said Australia was developing a "two-tier" drinking culture. Some were getting the message but many were drinking in excess of health guidelines.

"We have some people drinking sensibly but those who drink are drinking more harmfully," Professor Daube said. "These respondents are people who will not end up in ambulances and police cells but with chronic disease, liver disease and cancer.

"We make a huge mistake if we think alcohol is only a problem of Kings Cross on a Saturday night. A lot of alcohol damage is not visible in the short term."

One of the largest-ever surveys of Australian drug users, this study found 80 per cent of nearly 5850 respondents had used an illegal drug at some point in their lives, and almost all had tried alcohol.

The typical respondent was aged about 37, lived with a partner and worked full-time. About 60 per cent of respondents were male.

Key findings include:

High levels of prescription drug use; a third of more than 1900 people who used the painkiller codeine said they did so to get "high" or for relaxation. Australians are some of the biggest users of prescription drugs.

Almost one in 10 respondents had bought their drugs online. Just under 7 per cent had bought "research chemicals" or so-called "legal highs", higher than the global average.

Australians and New Zealanders reported some of the highest drug prices in the world. Cocaine was more than triple the price in many European countries, and ecstasy more than double.

Some 4.5 per cent had snorted a white powder without knowing what it was; almost one in 10 people in their early 20s admitted to doing so.

When people who had drunk in the past year were asked a series of questions known as the AUDIT scale – which identifies problem drinking by asking about both alcohol consumption levels and their impact on a person's life – about half showed signs of dangerous drinking.

Worryingly, about 1000 people were drinking at high-risk levels. About 350 scored more than 20 on the test, indicating a need for clinical help, while about 50 had ended up in emergency departments, often after drinking 10 or 20 drinks in a sitting.

Yet a quarter of people who scored 20 or more thought that compared with others their drinking was "average or less than average". And about 40 per cent of the other very high-risk drinkers thought their drinking posed little threat to their health.

University of NSW National Drug and Alcohol Research Centre director Professor Michael Farrell said many people who engaged in binge drinking did not believe they were at risk because "all their friends drink heavily".

"People often don't want to understand the hazards of drinking," Professor Farrell said. "They want to carry on having fun and don't see themselves in danger."

Survey founder Adam Winstock, a British psychiatrist and academic researcher, said that believing one's drinking was average was actually a predictor of higher levels of alcohol use.

"If you don't want to change your behaviours, thinking what you are doing is not risky and 'everyone is doing it' is just the sort of selective evidence you need to make you comfortable," he said.

He has created websites, drinksmeter.com and drugsmeter.com, that allow people to compare their alcohol and drug use with that of others. He said he was interested to see those who were dangerous drinkers were more likely to want to compare their use than others

"You can nudge people to change by helping them identify misperceptions around their own behaviours," he said.

Australian respondents made up about 7.5 per cent of the more than 72,000 people surveyed.

Dr Winstock said the Australians who participated were "a set of well-educated, mostly happy people who exercise a lot but who have a huge and rather diverse set of drug experiences".

"The idea of a typical drug user is a nonsense," he said.