Nearly 1 in 4 American adults lives with chronic pain, but women are significantly more likely to experience it than men—and now scientists may have found why. A groundbreaking study funded by the National Institutes of Health (NIH) points to specific immune cells as the key reason pain persists longer in women, opening doors to new treatments that don't rely on addictive opioid medications. Why Do Women Experience Chronic Pain Longer? Researchers at Michigan State University, led by Dr. Geoffroy Laumet, investigated how the immune system contributes to sex differences in pain recovery using mouse models. The findings, published in February 2026 in Science Immunology, revealed something surprising: males recovered from pain sensitivity much faster than females, even though both sexes experienced the same amount of inflammation. The difference came down to a single anti-inflammatory molecule called interleukin-10 (IL-10). Male mice had significantly higher levels of IL-10 in their skin than female mice. More importantly, males had more IL-10-producing immune cells called monocytes in their affected paws than females. The more of these cells they had, the faster they recovered from pain. To confirm this connection, researchers tested what happened when monocytes couldn't produce IL-10. Both male and female mice with low monocyte levels experienced longer-lasting periods of pain, just like the female mice in the original study. When researchers gave mice a drug that boosted IL-10-producing monocytes, pain recovery accelerated—but only in mice whose monocytes could actually make IL-10. What Role Do Sex Hormones Play? The research team discovered that sex hormones were responsible for these differences in pain duration. Male sex hormones were associated with higher IL-10 levels and faster pain recovery. This finding suggests that the biological differences between men and women—not just social or behavioral factors—directly influence how long chronic pain lasts. The researchers also examined real-world data from 245 people who had experienced traumatic injuries. Pain levels were similar in both men and women shortly after injury. However, after 12 weeks, men were in significantly less pain than women. Men also had higher levels of IL-10 and more monocytes in their bloodstream after their injuries. Higher IL-10 and monocyte levels were both associated with less pain 12 weeks after an injury. How Could This Lead to New Treatments? The implications of this research extend far beyond understanding why women suffer longer. "This opens new avenues for non-opioid therapies aimed at preventing chronic pain before it's established," explains Dr. Laumet. Rather than relying on pain-masking medications, future treatments could work by enhancing the body's natural pain-resolution mechanisms. IL-10's effects on pain depended on its ability to influence sensory neurons in the skin. Mice whose sensory nerve cells lacked the receptor for IL-10 had slower pain resolution, suggesting that boosting IL-10 production could help speed recovery by directly affecting how nerve cells respond to pain signals. Steps to Manage Chronic Pain While Waiting for New Treatments - Physical Therapy and Movement: Maintaining movement is one of the most important goals in chronic pain management. Physical or occupational therapy combined with supervised exercises can help restore function and prevent the condition from worsening over time. - Psychological and Behavioral Support: In many cases, psychological and behavioral therapy can be helpful for managing the emotional toll of chronic pain and improving overall quality of life. - Medication Options: Current treatments include nonsteroidal anti-inflammatory drugs (NSAIDs), topical medications like capsaicin or lidocaine, and certain antidepressants and anticonvulsants such as amitriptyline or gabapentin that are used for nerve pain treatment. What About Complex Regional Pain Syndrome? While the monocyte research focuses on general chronic pain recovery, another condition called complex regional pain syndrome (CRPS) represents one of the most severe forms of chronic pain. CRPS usually causes severe, constant, burning pain in an affected arm or leg and can be triggered by relatively minor injuries, trauma, fractures, infections, surgery, or even wearing a plaster cast. What makes CRPS particularly challenging is that the pain often is not limited to the area that was injured. In CRPS, nerves become overly sensitive, so painful signals become more painful, and common stimuli like light touch and temperature changes are experienced as pain. The condition can progress through three stages, and once it reaches the later stages, it becomes extremely difficult to treat. Early treatment is critical for CRPS. About half of people with CRPS continue to experience pain six months after treatment was started, highlighting the importance of getting care from health care professionals who have expertise in treating this condition, including anesthesiologists, pain specialists, vascular surgeons, physical therapists, and occupational therapists. The Bottom Line The discovery that IL-10-producing monocytes drive sex differences in pain recovery represents a major breakthrough in understanding why chronic pain affects men and women differently. By manipulating IL-10 levels, researchers may be able to help speed up recovery from pain and overcome these biological sex differences. For the millions of Americans—particularly women—living with chronic pain, this research offers hope that future treatments could work with the body's natural healing mechanisms rather than simply masking symptoms with opioids.
