Aussie pensioners struggling to make ends meet are selling their prescription medication to junkies and drug dealers, with some painkillers fetching up to $4000 a box.

Queensland doctors have warned that dealers are also targeting vulnerable seniors, some who survive off a $766 fortnightly pension, and have been approaching them outside pharmacies, News Corp reports.

The most sought-after drugs are opioid pills MS Contin and OxyContin, and Fentanyl patches, commonly prescribed for chronic pain and cancer care.

Hervey Bay GP Dr Ken Treichel says he’s banned six elderly patients from his surgery in the past year for selling their medication.

“It’s absolutely rampant,” he saidr.

“I actually see people (selling). I’ve seen people walk up to them, bring the money out and do the deal, standing in the car park.”

Drug and Serious Crime Group Sergeant Adam Frost said people of all ages had been busted buying and selling prescription drugs, including the elderly.

“It’s not an excuse – a 78-year-old on the pension and finding it tough might resort to that sort of supplementary income,” he said.