IBS, or irritable bowel syndrome, is a condition in which your bowels become hyper-irritable, causing symptoms like bloating, stomach cramps, diarrhea, and constipation.
SIBO, or small intestinal bacterial overgrowth, is the excessive growth of bacteria in the small bowel. These bacteria cause abdominal discomfort, bloating, diarrhea, and nutrient deficiencies in severe cases.
Fibromyalgia (FM) is a cluster of various signs and symptoms such as chronic widespread body pain, unrelenting fatigue, and mood, bowel and reproductive disturbances.
So, you see the above three conditions have one or more overlapping features. Scientists have been able to spot a link or commonality between these conditions. Moreover, experts like Dr. Kim also stress how important it is for gastroenterologists to know about fibromyalgia to be able to address the symptoms more appropriately.  According to Dr. Kim, the medical community may sometimes not pay attention to FM symptoms when they diagnose or address symptoms of IBS. This creates challenges while managing the IBS symptoms.
How the two digestive ailments (IBS and SIBO) go hand in hand with fibromyalgia is worth-noticing. But speaking of the relation between FM and IBS is even more interesting. For instance, studies show that about 32.5% of people with IBS are found to have FM. Similarly, about 48% of people with FM also have IBS. 
Leaky Gut is likely to be the shared culprit
Leaky gut, or more appropriately, “increased intestinal permeability” causes toxins and disease-causing bugs to cross the protective gut lining and break into your system. Surprisingly, leaky gut not only plays a role in IBS and SIBO — which are bowel disorders — but also in fibromyalgia.
A mounting piece of evidence shows that disruption of the gut barrier can impair local GI functions as well as enable the spread of toxins from harmful bacteria with subsequent gut inflammation. The level of these toxins in your body is what tells us how severe your disease is going to be. Moreover, these toxins may also contribute to symptoms like muscle tension, fatigue, difficulties with concentration and memory seen in FM. 
Dr. Maes also supported the view of targeting the weakened gut barrier as a novel pathway in FM with a leaky gut diet, and possibly by drugs. 
Dysbiosis (altered gut bacterial balance) and FM
We know that disarray in the balance of gut microbiome spurs bowel disorders like IBS and SIBO. But not many are aware that these messed up bacteria may also be the cause of FM symptoms. The gut-brain axis theory explains the tie between the altered microbiome and the mind-related issues in FM. Then we also have a muscle-gut axis that may act as a driver for the muscular symptoms of FM due to an out-of-balance gut harmony. 
SIBO may precede both IBS and Fibromyalgia
Both IBS and FM have a link with SIBO. But it now appears that SIBO may have a stronger bond with FM than IBS.
The bad bacteria in SIBO emit hydrogen, which can be detected by testing your breath for hydrogen in a test called the “hydrogen breath test.” In 2004, for the first time, researchers noted that 100% of patients with FM who partook in the study, had SIBO, and that the degree of pain in FM almost equaled the hydrogen levels in the breath test.  Further supporting this view, researchers deduced that the breath test is more likely to be abnormal in people with fibromyalgia than in people with IBS.
In fact, another study conducted in the same year revealed that people with FM who were found to have SIBO, reported a marked improvement in their FM symptoms after ridding the bacterial growth in their small bowels by antibiotics. 
Cutting to the chase
SIBO is at the heart of fibromyalgia — and both these conditions have an undeniable link with IBS. In addition, we know from former posts that both SIBO and IBS respond to probiotics.
It wouldn’t be wrong to say — a healthy lifestyle, a diet high in fiber with a moderate intake of fats and proteins, and probiotics — could rebalance the gut bacteria and reduce the symptoms of FM. Nonetheless, researchers still need to further dig in to better assess the role and influence of the microbiota in people with fibromyalgia.
- Kim YS. Why should gastroenterologists know about fibromyalgia? Common pathogenesis and clinical implications. J Neurogastroenterol Motil. 2011;17(1):1–3. doi:10.5056/jnm.2011.17.1.1.
- Pimentel M, Wallace D, Hallegua D, et al. A link between irritable bowel syndrome and fibromyalgia may be related to findings on lactulose breath testing. Ann Rheum Dis. 2004;63(4):450–452. doi:10.1136/ard.2003.011502.
- Maes M, Leunis JC. Normalization of leaky gut in chronic fatigue syndrome (CFS) is accompanied by a clinical improvement: effects of age, duration of illness and the translocation of LPS from gram-negative bacteria. Neuro Endocrinol Lett. 2008;29(6):902-10.
- Tomasello G, Mazzola M et al. Intestinal dysbiosis and hormonal neuroendocrine secretion in the fibromyalgic patient: Relationship and correlations. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2018. doi: 10.5507/bp.2018.051.
- Wallace DJ, Hallegua DS. Fibromyalgia: the gastrointestinal link. Curr Pain Headache Rep. 2004;8(5):364-8