Powerful opiate-based painkillers carry too many risks to be used to treat arthritis pain, researchers are warning patients.

Reuters reported Oct. 7 that researcher Eveline Nuensch of the University of Bern in Switzerland and colleagues compared opiate-based drugs to a placebo or no treatment in a group of 2,268 patients suffering from osteoarthritis in the knee or hip. They concluded that the “small to moderate” increase in pain relief offered by drugs like codeine and OxyContin was not worth the risk of addiction and the sometimes severe side-effects associated with opiate-based medications.

“It is striking how little additional benefit patients with hip or knee pain can expect from taking opiates compared to placebo,” said Nortin Hadler, a spokesperson for the American College of Rheumatology, who said that for arthritis patients, the pain relief offered by acetaminophen is “as good as it gets, and much better than any other option in terms of risk/benefit ratio and cost/effectiveness ratio.”

The findings were published in the Cochrane Library.