There is new evidence that fibromyalgia, and the chronic pain associated with it, could worsen opioid use disorder. Researchers at The Ohio State University Wexner Medical Center, College of Medicine and University of Michigan report their findings in Pain.

Scientists have long suspected a connection between opioid use disorder (OUD) and chronic pain. Many people first use opioids to treat pain. Chronic pain has been tied to worsening of OUD and even relapse among those in recovery from opioid addiction. However, researchers didn't know whether all pain has the same effect on OUD, or whether certain pain diagnoses might have a much larger impact. Different impacts might lead to more targeted treatments for people with pain and OUD.

Symptoms of fibromyalgia include widespread body pain, extreme tiredness and difficulty thinking and sleeping. This condition is thought to involve unusually strong pain signals in the brain.

"Many of the brain pathways and chemicals believed to be involved in fibromyalgia are also involved in opioid addiction. This overlap made us suspect fibromyalgia might worsen OUD. It's sort of a double hit hypothesis," said Dr. O. Trent Hall, lead author and an addiction medicine physician in Ohio State's Department of Psychiatry and Behavioral Health.

The research team surveyed 125 people living with pain and OUD, 39 (31%) of whom met criteria for fibromyalgia. Although all participants had pain and OUD, those with fibromyalgia were much more likely to say pain had worsened their addiction.

Specifically, those with fibromyalgia more often agreed that pain caused them to continue and increase their opioid use, and that they put off seeking help out of fear their pain would be unbearable if they stopped using opioids.

"These are serious findings. Worries about pain may cause people with fibromyalgia and OUD to delay getting addiction treatment. In our current overdose crisis, every day a person puts off OUD treatment might be the last day of their life," said Dr. Julie Teater, study co-author and medical director of addiction medicine at Ohio State Wexner Medical Center.

Researchers also found fibromyalgia was associated with greater odds of fearing that pain might cause relapse in the future.

"There are ways we can help people living with fibromyalgia. It's possible that combining lessons learned from years of studying fibromyalgia might one day inform new treatments for chronic pain and OUD. More research is needed. This is just the beginning," said senior author Dr. Daniel J. Clauw, director of the Chronic Pain and Fatigue Research Center at the University of Michigan.

Craig Bryan and Dr. K. Luan Phan from Ohio State were also involved in this research.