Fibromyalgia and the Gut-Brain Axis:

Many people living with fibromyalgia experience digestive symptoms such as nausea, abdominal pain, bloating, constipation, diarrhea, or irritable bowel syndrome (IBS). While these symptoms may seem unrelated tochronic pain, research suggests they are often connected through the gut-brain axis—the two-way communication network linking the digestive system and the brain.

The gut-brain axis allows the brain, spinal cord, nerves, hormones, immune system, and trillions of microorganisms in the gut to continuously exchange information. In people with fibromyalgia, this communication may become disrupted due to changes in how the central nervous system (CNS) processes pain and other sensory signals. This heightened sensitivity—often referred to as central sensitization or nociplastic pain—may not only amplify pain but also increase awareness of normal digestive sensations, making bloating, gas, nausea, and abdominal discomfort feel more intense.

The autonomic nervous system, which regulates digestion without conscious effort, may also function differently in fibromyalgia. Increased physiological stress and changes in nervous system regulation can influence stomach emptying, intestinal movement, and communication between the brain and digestive tract. These changes may contribute to common gastrointestinal conditions, including IBS, which occurs more frequently in people with fibromyalgia than in the general population.

Researchers are also studying the role of the gut microbiome—the community of bacteria living in the digestive tract. While differences in gut bacteria have been identified in some individuals with fibromyalgia, it remains unclear whether these changes contribute to the condition or develop as a result of it. More research is needed before specific microbiome-targeted treatments can be recommended.

Although digestive symptoms can be frustrating, they are real and deserve attention. Comprehensive treatment often includes addressing sleep, stress, physical activity, nutrition, and psychological factors that influence nervous system regulation. Working with your healthcare team to identify dietary triggers, manage IBS symptoms, and improve nervous system health may help reduce gastrointestinal symptoms while supporting overall well-being.

Key Takeaways

• The gut-brain axis is the communication network connecting the digestive system and the central nervous system.

• Changes in nervous system processing may contribute to nausea, bloating, gas, abdominal pain, and IBS symptoms in fibromyalgia.

• Digestive symptoms are common in fibromyalgia symptoms and reflect real biological changes rather than "just stress."

• The gut microbiome is an active area of research, but scientists are still determining its role in fibromyalgia.

• A comprehensive, evidence-based treatment approach that supports nervous system regulation may improve both pain and digestive symptoms.

References

Bonaz, B., Bazin, T., & Pellissier, S. (2018). The vagus nerve at the interface of the microbiota-gut-brain axis. Frontiers in Neuroscience, 12, 49.

Clauw, D. J. (2014). Fibromyalgia: A clinical review. JAMA, 311(15), 1547–1555.

Ford, A. C., Lacy, B. E., & Talley, N. J. (2017). Irritable bowel syndrome. New England Journal of Medicine, 376(26), 2566–2578.

Häuser, W., Ablin, J., Fitzcharles, M. A., et al. (2015). Fibromyalgia. Nature Reviews Disease Primers, 1, 15022.

Kim, Y. K., & Shin, C. (2018). The microbiota-gut-brain axis in neuropsychiatric disorders. International Journal of Molecular Sciences, 19(2), 459.

Siracusa, R., Paola, R. D., Cuzzocrea, S., & Impellizzeri, D. (2023). Fibromyalgia: Pathogenesis, mechanisms, diagnosis and treatment options update. International Journal of Molecular Sciences, 24, 4001.

Considering Treatment for Fibromyalgia? At McLean Health Psychology Specialists, we provide individual, evidence-based care for adults living with fibromyalgia, chronic pain, and complex medical conditions. If you're ready to work with a clinician who specializes in the unique challenges of fibromyalgia, we invite you to schedule a consultation and learn how health psychology can support your treatment journey.

Learn more about our fibromyalgia treatment program.

About the Author

This article was written by Catherine DeBoer, PsyD, ABPP, a Board-Certified Clinical Health Psychologist and fibromyalgia treatment specialist located in McLean, VA. The information provided is based on current scientific research and clinical expertise and is intended for educational purposes only. It should not be considered a substitute for personalized medical advice, diagnosis, or treatment.

© 2026 Catherine DeBoer, PsyD, ABPP. All rights reserved. No portion of this publication may be reproduced, distributed, or transmitted in any form or by any means without prior written permission, except for brief quotations used for educational or scholarly purposes with appropriate attribution.