Steroids have overtaken heroin and methamphetamines as the substance of choice for people injecting drugs in New South Wales, with people as young as 15 shooting up the drug.

The figures come from a study carried out by the Australian Needle and Syringe Program.

It found that up to 74 per cent of new injecting drug users in New South Wales were shooting up steroids, up from just 27 per cent in 2003.

Australian Medical Association president Steve Hambleton says bulked-up sports stars are influencing young people to take steroids.

"The concerns are that it's the average person in the street now that's starting to think about these substances to attain the perfect body image," he said.

"We used to worry about our girls, but now it's the young boys as well."

Meanwhile Prime Minister Tony Abbott has questioned whether steroid abuse is contributing to incidents of street violence.

"I'm appalled by the violent binge drinking culture that now seems so prevalent, especially at "hot spots" in our big cities," the PM wrote in the Daily Telegraph.

"We also have to identify if drugs like steroids are also contributing to this outbreak of violent behaviour.

"There is enough anecdotal evidence from police and our emergency rooms that what we are seeing is not fuelled by alcohol alone. Alcohol is consumed along with other drugs such as ice and other amphetamines."

On Thursday Mr Abbott called for the perpetrators of violent unprovoked attacks to feel the full force of the law, saying the attacks on innocent victims were "utterly cowardly" and marked a "vicious, horrible change" in society.

"Tragically, it's not just one young life that is destroyed but many," he said. "In an instant, one person becomes a victim, another a criminal - and the lives of their families are irrevocably damaged.

"We need to tackle this issue in a comprehensive and considered way. We don't need kneejerk reactions and stunts that give the illusion of action, but don't make any real, lasting difference."