Irritable Bowel Syndrome in Fibromyalgia and CFS

Fibromyalgia (FMS), chronic fatigue syndrome (ME/CFS), and irritable bowel syndrome (IBS) frequently go together. No one really knows why, but we do know that all three conditions can include imbalances of the chemical serotonin, although in FMS and ME/CFS it's an imbalance in the brain, while with IBS it's in the gut.

Like FMS and ME/CFS, IBS by itself can be debilitating and can impose a lot of restrictions on your diet and lifestyle. Anything that causes pain or stresses in your body can exacerbate FMS/ME/CFS symptoms, so it's especially important to treat your IBS. With some effort, IBS symptoms typically can be well managed.

Woman laying on couch with hot water bottle
 OMG / Getty Images

What is Irritable Bowel Syndrome?

When you have IBS, your intestine does not function properly. The intestine itself is fine, but some people may have a lower pain tolerance when it comes to intestinal stretching and movement, or they could possibly have disordered intestinal muscle movement.

People with IBS can have urgent diarrhea or constipation or can have alternating bouts of each. They also have frequent abdominal pain. While most people with FMS don't have abdominal pain related to digestion, IBS pain often feels similar to the pain of FMS.

Researchers don't yet know why IBS develops, but they do know that it often starts after severe gastroenteritis (so-called "stomach flu") or an extremely stressful event. Researchers currently are looking into what's called the brain-gut connection in order to better understand the relationship between stress and IBS.

Why Do These Illnesses Go Together?

The short answer to the question of why these conditions often occur together is, "Nobody knows." The long answer is, at this stage, speculative. Similarities that are worth researchers' time include:

  • All three conditions may involve serotonin imbalances
  • IBS and ME/CFS both can begin after another illness
  • Each of these conditions is strongly linked to stress

Right now, we don't know the underlying causes of any of these conditions, and we likely won't understand their relationship until we better understand their causes and mechanisms. However, based on research, an emerging umbrella term is central sensitivity syndromes.

Symptoms of Irritable Bowel Syndrome

Symptoms of IBS include pretty much any unpleasant abdominal symptoms you can think of. Along with constipation and/or diarrhea, major symptoms are:

  • Nausea and vomiting
  • Gas
  • Bloating
  • Abdominal distention

Symptoms not associated with IBS

  • Bloody stool
  • Anemia
  • Abdominal pain and cramping that wakes you up or keeps you awake
  • Significant, unintentional weight loss

Any time you have a marked change in bowel function, talk to your healthcare provider.

Don't dismiss any of these symptoms as just another aspect of FMS or ME/CFS, because neither of those conditions involves them.

Diagnosing IBS

IBS is diagnosed by identifying defined patterns of signs and symptoms and limited diagnostic testing.

Before diagnosing you with IBS, your healthcare provider may need to rule out inflammatory bowel disease (ulcerative colitis and Crohn's disease), colon cancer, food sensitivities, and other conditions with similar symptoms.

IBS Treatment

IBS generally is a chronic condition, but you have a lot of options for feeling significantly better.

Drug treatments for IBS generally include:

  • Prescription diarrhea medications
  • Prescription constipation medications
  • Over-the-counter medications
  • Dietary changes
  • Stress management techniques

Sticking to a treatment regimen can minimize your symptoms, which means they'll have much less impact on your life as well as on FMS or ME/CFS.

Having Irritable Bowel Syndrome & FMS/ME/CFS

When you're dealing with multiple conditions, make sure all your healthcare providers and your pharmacist are aware of the medications, supplements, and dietary limitations you face. (Some medications may include ingredients that bother you.)

The good news is that IBS treatments don't generally conflict with FMS/ME/CFS treatments, and the focus on a healthy diet can be beneficial to your overall health. One key to feeling better is learning all you can about your condition.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Paredes S, Cantillo S, Candido KD, Knezevic NN. An association of serotonin with pain disorders and its modulation by estrogens. Int J Mol Sci. 2019;20(22). doi:10.3390/ijms20225729

  2. Kohlstadt I. Advancing Medicine with Food and Nutrients. Boca Raton, Florida: CRC Press.

  3. Medline Plus. Irritable bowel syndrome.

  4. International Foundation for Gastrointestinal Disorders. Symptoms of IBS.

  5. International Foundation for Gastrointestinal Disorders. Diagnosis of IBS.

  6. International Foundation for Gastrointestinal Disorders. IBS symptom treatments.

  7. Nordling J, Cervigni M. Bladder Pain Syndrome: A Guide for Clinicians. New York NY: Springer Publishing Company.

By Adrienne Dellwo
Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic.