Facebook has become saturated with official and unofficial alcohol marketing in a trend health experts say is exposing young people to a relentless promotion of binge drinking.

Alcohol brands have an average of 75,000 fans on 11 Australia-based official Facebook pages; some have as many as 50 times that number on unofficial pages set up by fans.

 TELL US ABOUT YOUR DRUG AND ALCOHOL USE: Take the Global Drug Survey here.

Research by the University of Wollongong found some official Facebook pages appeared to promote excessive drinking. The unofficial pages were far worse.

"In some cases it's appalling," lead researcher and director of the university's centre for health initiatives, Sandra Jones, said.

"I think [that] as parents, or a community, we are very concerned about our child's friends in the real world but we're not aware of some of the 'friends' they have online that can be quite harmful."

Marketing on official alcohol companies' Facebook pages included posts that suggested drinking early in the morning, positive depictions of huge numbers of empty alcohol containers, and a giveaway of a year's supply of beer.

The latter turned out to be for the cash equivalent, although the terms and conditions stated a year's supply was a case of beer a week, an amount massively in excess of safe drinking guidelines.

Professor Jones said Facebook and alcohol companies needed to crack down on fans' pages, some of which reflected dangerous attitudes towards drinking.

She is concerned social media means some people had become unofficial marketers for alcohol brands and for dangerous drinking practices.

"It used to be the companies marketing to us but now, particularly with young people, it's us marketing to ourselves," she said.

University of Western Sydney business lecturer Ann Dadich said research had shown that the more exposure young people had to alcohol marketing, the more likely they were to start drinking, and to drink more than others when they did.

Dr Dadich's research on alcohol marketing on Twitter showed that messages were spread extremely widely on social media. One company she studied sent only 236 tweets, but these were shared more than 13,500 times.

"Popular hash tags also increased the likelihood that they would be seen by under-18s," she said. "It's time to seriously consider how alcohol companies use social media, and the likely consequences associated with that practice."

Foundation for Alcohol Research and Education chief executive Michael Thorn said it was the sheer volume of the exposure to advertising that concerned him. "I think it's a growing issue that runs the risk of becoming a major problem," he said.

Mr Thorn said spirits companies appeared to be particularly active on social media. Many music events had considerable sponsorship by alcohol companies, combined with social media marketing using photographs taken at events, and then branded and shared this on Facebook, he said.

Alcohol Beverages Advertising Code spokeswoman Denita Wawn said the industry had improved its marketing on social media. "We have had very, very few complaints about social media advertisements," she said.

Last month ABAC released a best practice guide advising drinks companies to always moderate user comments.