Former NRL stars Matthew Johns and Mark Geyer have warned painkiller abuse is rife and an epidemic in the NRL.

Johns said the hospitalisation of South Sydney pair Aaron Gray and Dylan Walker should serve as a wake-up call for players, doctors and clubs.

"These days, many players, not just some, take prescription drugs for kicks," Johns said on MMM's Grill Team.

"Ten years ago it was a bit of a problem, these days it's absolutely rife.

"The abuse of these is widespread in rugby league. I believe it's widespread in sport."

Former New South Wales and Kangaroos representative Geyer admitted he was addicted to painkillers in the mid-1990s.

"I was playing for Perth and I had several knee operations," Geyer said. "After every operation I would be prescribed Panadeine Forte.

"After a while the doctor said 'mate, you don't need them anymore', but I was still chasing that feeling Panadeine Forte was giving me."

He said abuse among players was now at epidemic proportions.