The revelation that an Australian soldier serving in Afghanistan may have overdosed on drugs comes as no surprise to addiction experts.

One even says a risk of sending soldiers to Afghanistan is that some of them are going to become heroin dependent.

A senior lawyer is set to conduct an official inquiry into how the experienced Australian commando suffered a suspected overdose nearly a week ago.

A bottle of pills and white powder were found in the soldier's room.

He was found unconscious and unresponsive in his room in Tarin Kowt in Uruzgan province last Friday and remains in a serious condition in a military hospital in Germany.

Australian soldiers already face random drug testing, but now there will be testing of the entire Special Operations Task Force in Afghanistan.

Dr Alex Wodak, director of the Alcohol and Drug Service at St Vincent's Hospital in Sydney, says drug use was a major problem for Soviet troops in Afghanistan and the US military is also now facing an increase in addiction.

He says many soldiers turn to drugs simply to cope with life in a war zone.

"Life is unbearable," he said. "You don't know whether you're going to be alive in 10 minutes' time or not.

"Life has very few pleasures; you're very uncomfortable, it's either very hot or very cold, the food's pretty awful, the ever-present smell of death and you see some of your closest buddies die before your eyes.

"So life is really unbearable and heroin's cheap."

Afghanistan produces 93 per cent of the world's opium, the key ingredient of heroin.

"Afghanistan is a place where there's a lot of narcotics," said Defence Force Chief Angus Houston.

"They're grown there and they're manufactured there and this is a place where narcotics are more freely available probably than anywhere else in the world."

Men and women in Australia's Defence Force already face random and targeted drug tests.

They generally have fewer positive results than people in other professions who face drug testing, such as miners and police officers.

But Defence Minister John Faulkner still wants to know if the Defence testing program is adequate.

The history of opiate use by soldiers dates back to the American Civil War.

Heroin abuse was a big problem for the US military during the Vietnam War, exacerbated by the fact its military contained large numbers of conscripted soldiers.

In Afghanistan, however, all US troops are volunteers.

Dr Ben Wadham, an expert on army culture from Flinders University in South Australia, says drug use is also a problem in the Australian military.

"The Defence Force has had an ongoing issue with drug use amongst its ranks," he said.

"They've put together a number of inquiries and different strategies to address drug use but it remains a persistent issue.

"Drinking has always been an issue in the military and remains so, but even more so drugs become a way of young men dealing with the stressors of the military but also bonding together."

Work hard, play hard

Dr Wadham says armed forces culture begins by constructing a strong difference between a soldier and a civilian.

"Soldiers bond together in particular ways and they also engage in quite risky operations, risky work, quite hard work," he said.

"The way that particularly men in those armed corps bond together is by engaging in the work hard, play hard mentality."

John Jarrett, president of the Young Diggers, a group that helps Australian servicemen and women cope with health issues, says self-medication through alcohol or drugs is a problem.

"We've noticed that most of the self-medication is from alcohol abuse, but mainly after they get back," he said.

"But yes, there are occasions where some of the troops will self-medicate over there I presume, but most of what we're hearing is the alcohol abuse back in country."

Drug testing is conducted among members of the Australian armed forces and there have been claims the military lacks the necessary strategies to deal with the problem.

But Mr Jarrett says he has seen some promising signs in recent months.

"We've noticed in the past few months that the Defence Force are getting a lot better at that," he said.

"I know it's probably not our place to comment on it, but we're very pleased with what we are seeing from the military, that they've actually stood up and we're seeing them do things and doing it well."

Mr Jarrett has urged the military to maintain strong support for those soldiers affected by substance abuse.