Due to the thousands of overdoses caused by prescription medications each year, it is important that scientists research these powerful medications as much as possible. Researchers at the University of Colorado Boulder recently conducted a study to see if these medications have any adverse side effects, specifically prolonging chronic pain. Their findings are published in the Proceedings of the National Academy of Sciences.

The researchers used lab rats that had a spinal nerve injury. The injury was treated with five days worth of opioid medications. After the medication, the nerves actually responded by getting worse, inflaming and causing prolonged chronic pain. It was found that this pain after the medication lasted several months.

The researchers note that although this study was conducted on rats, the effects of the medication may be similar in humans. Since most people are prescribed opioid medications for chronic pain, they may make the pain worse.