Fibromyalgia or CIRS? Could Mould Be Behind Your Pain?

If you have been diagnosed with fibromyalgia, CIRS is worth considering when your symptoms seem tied to a building. Look for these signs:

• your pain, fatigue and brain fog started or got worse while you lived or worked in a water-damaged building
• other people in the same building have symptoms too
• you feel clearly better away from a particular place

Fibromyalgia is diagnosed from a pattern of symptoms. No blood test confirms it. CIRS (Chronic Inflammatory Response Syndrome) can cause a very similar picture. But CIRS is linked to an exposure, and doctors assess it with a vision test and specific blood markers.

The two can look alike. The official fibromyalgia criteria state that a fibromyalgia diagnosis does not exclude other illnesses.

What is fibromyalgia?

Fibromyalgia is a long-term condition. Its main feature is chronic pain all over the body. It comes with sleep that does not refresh you, physical exhaustion and problems with thinking [1].

Symptoms that fit fibromyalgia are found in roughly 2–4% of people worldwide, about 2 to 4 in 100. Far fewer actually receive the diagnosis [1].

The cause is not known. Researchers describe fibromyalgia as a “centralised” pain condition. The central nervous system (the brain and spinal cord) amplifies pain signals. Fatigue, memory problems and sleep and mood problems often come with it [2].

Genetic, biological and psychological factors are thought to work together, but the details are unclear. Doctors still debate the condition [1].

How is fibromyalgia diagnosed?

No lab test or scan confirms fibromyalgia. The diagnosis is based on your symptom history and an examination. Blood tests are used to look for other illnesses that could explain the symptoms [1][2].

The American College of Rheumatology (ACR) criteria have changed over the years:

The 2016 revision adds an important point. A fibromyalgia diagnosis is valid regardless of other diagnoses, and it does not exclude other clinically important illnesses [5]. In other words, having fibromyalgia does not mean that nothing else is going on.

Which symptoms do fibromyalgia and CIRS share?

Many. Dr Ritchie Shoemaker’s group uses a CIRS symptom list of 37 symptoms in 13 clusters. Several are the same complaints that lead to a fibromyalgia diagnosis [6]:

• fatigue and weakness
• muscle aches, joint pain and morning stiffness
• unusual pains, such as sharp “ice-pick” pains
• headache
• memory problems, difficulty concentrating and finding words (“brain fog”)
• numbness and tingling

Pain, fatigue and thinking problems are central to both. So someone with CIRS could easily fit the fibromyalgia criteria.

Expert view The 2018 consensus statement of Shoemaker’s group goes further. It advises CIRS doctors to look past an existing fibromyalgia diagnosis when they assess a patient [6]. That is the group’s clinical opinion, not a finding from a study that compared the two.

How is CIRS different from fibromyalgia?

The main differences are in what is thought to cause the illness and in what can be measured.

1. Exposure history. CIRS is described as an inflammatory illness that follows exposure to biotoxins [6][7]. Biotoxins are natural poisons made by living things, most often moulds and other microbes in water-damaged buildings. Shoemaker’s group notes that symptoms and test results alone cannot reliably tell one biotoxin illness from another. So the exposure history is a core part of the diagnosis [6]. Fibromyalgia has no required trigger.

2. Symptoms beyond pain. The CIRS symptom list also includes [6]:

• breathing and sinus symptoms
• light sensitivity, red eyes and blurred vision
• strong thirst and frequent urination
• night sweats and problems regulating body temperature
• static shocks, a metallic taste and vertigo

In Shoemaker’s approach, eight or more of the 13 symptom clusters in an adult support a CIRS diagnosis [6].

3. The VCS test. The visual contrast sensitivity (VCS) test measures how well you see small differences between shades of grey. In a 2006 study by Shoemaker and House, all 26 people who fell ill in water-damaged buildings had abnormal VCS results at the start [7]. The VCS test is not part of fibromyalgia diagnosis.

4. Blood markers. In the Shoemaker approach, doctors assess CIRS with blood markers such as MSH, MMP-9, VEGF, C4a, TGF-β1 and VIP, often together with HLA-DR typing (a gene test) [6][7]. These markers reflect hormones, inflammation and blood vessel signalling. In fibromyalgia, routine blood tests are usually normal. They are used only to rule out other conditions [1][2].

Comparison table

	Fibromyalgia	CIRS
Core symptoms	Chronic widespread pain, fatigue, unrefreshing sleep, thinking problems [1]	Symptoms in many body systems: fatigue, aches, joint pain, thinking problems, plus breathing, eye, thirst, temperature and other symptoms [6]
Suspected cause	Unknown; the nervous system amplifies pain signals [2]	Biotoxin exposure, most often in water-damaged buildings [6][7]
Diagnosis	ACR 2016 criteria: pain index, symptom severity, symptoms for ≥ 3 months [5]	Exposure history, symptom clusters, VCS test and blood markers (Shoemaker approach) [6]
Lab findings	No confirming test; blood tests rule out other illness [1]	Abnormal markers such as MSH, MMP-9, C4a, TGF-β1, VIP [6][7]
Main treatment	Education, exercise, psychological therapies and medicines for selected symptoms [8]	Ending the exposure, then the Shoemaker protocol [9]
Evidence base	Large body of research and international guidelines [8]	Mostly from one group of doctors; independent trials lacking [9]

Is there research on mould exposure and fibromyalgia?

Very little. In a PubMed search in October 2026, we could not find any study that tested people with fibromyalgia for mould exposure, water-damaged housing or CIRS markers. So whether some people diagnosed with fibromyalgia actually have CIRS is an open question, not an established fact.

There are a few indirect findings:

• One small study In a Finnish questionnaire study, nurses and midwives in a moisture-damaged hospital reported muscle and joint pain more often than an unexposed comparison group: 51% vs 22%, about half vs about 1 in 5. They also reported more fatigue, brain fog and nerve symptoms [10]. The study was small, relied on what people reported themselves and did not diagnose fibromyalgia.
• Preliminary research A Spanish study found clearly more mast cells in skin samples from 63 people with fibromyalgia than in volunteers from the general population [11]. Mast cells are immune cells that store histamine. A review has proposed that mould toxins act partly through them [12] (see histamine and chronic symptoms). This is a possible meeting point between the two conditions. But no study has connected it to mould exposure.

Can you have both fibromyalgia and CIRS?

Possibly. The fibromyalgia criteria clearly allow other diagnoses alongside it [5]. And doctors diagnose the two conditions in completely different ways.

So you could meet the fibromyalgia criteria and, after further tests, also show findings that point to CIRS. How often this happens has not been studied.

What should you do if you have fibromyalgia and suspect mould?

These steps help you and your doctor decide whether CIRS is worth looking into:

1. Write down your exposure history. The box below shows how.
2. Do the VCS test. It is quick, cheap and can be done online. An abnormal result does not prove CIRS, and a normal result does not rule it out. But it is useful information to take to your doctor. Read more about the VCS test.
3. Talk to your doctor about tests. How CIRS is diagnosed explains the blood tests used in the Shoemaker approach (such as MSH, MMP-9, C4a, TGF-β1, VIP and HLA-DR). Not every doctor knows CIRS, so bring your notes and the test results you already have.
4. Deal with the exposure. If your home or workplace has water damage, have it assessed and repaired, or move away from it. This is the first step in CIRS treatment. Our water damage guide explains what to look for.
5. Keep your current care. Do not stop fibromyalgia treatments or medicines on your own. Exercise is the only fibromyalgia treatment with a “strong for” recommendation in the European (EULAR) guidelines [8]. You can continue it while other causes are being looked into.

How strong is the evidence?

• Well studied Fibromyalgia rests on decades of research, tested diagnostic criteria and international treatment guidelines [5][8].
• Preliminary research The CIRS side is much thinner. The symptom clusters, the VCS findings and the blood marker approach come mainly from Dr Shoemaker and colleagues. A 2024 review by CIRS practitioners found the Shoemaker protocol to be the only CIRS treatment with documented clinical efficacy. Independent controlled trials are still lacking [9].
• Not studied: No study has compared fibromyalgia and CIRS directly. None has measured how often people with fibromyalgia have been exposed to water-damaged buildings.

The same question comes up with chronic fatigue syndrome, which we compare in CIRS vs ME/CFS.

So CIRS is a possibility to look into, not an explanation to assume. If your fibromyalgia symptoms are clearly tied to a building, it is reasonable to ask your doctor about it.

Remember these

Check yourself: Can you name two things that CIRS has and fibromyalgia does not?

What next?

• Go through the CIRS symptom checklist.
• Read how CIRS is diagnosed.
• Compare CIRS with another look-alike in CIRS vs ME/CFS.

References

1. Häuser W, Ablin J, Fitzcharles MA, et al. Fibromyalgia. Nat Rev Dis Primers. 2015;1:15022. PubMed
2. Clauw DJ. Fibromyalgia: a clinical review. JAMA. 2014;311(15):1547–1555. PubMed
3. Wolfe F, Smythe HA, Yunus MB, et al. The American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia. Report of the Multicenter Criteria Committee. Arthritis Rheum. 1990;33(2):160–172. PubMed
4. Wolfe F, Clauw DJ, Fitzcharles MA, et al. The American College of Rheumatology preliminary diagnostic criteria for fibromyalgia and measurement of symptom severity. Arthritis Care Res (Hoboken). 2010;62(5):600–610. PubMed
5. Wolfe F, Clauw DJ, Fitzcharles MA, et al. 2016 Revisions to the 2010/2011 fibromyalgia diagnostic criteria. Semin Arthritis Rheum. 2016;46(3):319–329. PubMed
6. Shoemaker R, Johnson K, Jim L, et al. Diagnostic process for chronic inflammatory response syndrome (CIRS): a consensus statement report of the Consensus Committee of Surviving Mold. Internal Medicine Review. 2018;4(5):1–47. PDF
7. Shoemaker RC, House DE. Sick building syndrome (SBS) and exposure to water-damaged buildings: time series study, clinical trial and mechanisms. Neurotoxicol Teratol. 2006;28(5):573–588. PubMed
8. Macfarlane GJ, Kronisch C, Dean LE, et al. EULAR revised recommendations for the management of fibromyalgia. Ann Rheum Dis. 2017;76(2):318–328. PubMed
9. Dooley M, Vukelic A, Jim L. Chronic inflammatory response syndrome: a review of the evidence of clinical efficacy of treatment. Ann Med Surg (Lond). 2024;86(12):7248–7254. PubMed
10. Hyvönen S, Lohi J, Tuuminen T. Moist and mold exposure is associated with high prevalence of neurological symptoms and MCS in a Finnish hospital workers cohort. Saf Health Work. 2020;11(2):173–177. PubMed
11. Blanco I, Béritze N, Argüelles M, et al. Abnormal overexpression of mastocytes in skin biopsies of fibromyalgia patients. Clin Rheumatol. 2010;29(12):1403–1412. PubMed
12. Ratnaseelan AM, Tsilioni I, Theoharides TC. Effects of mycotoxins on neuropsychiatric symptoms and immune processes. Clin Ther. 2018;40(6):903–917. PubMed

Please note: this article is for information only and does not replace a diagnosis or treatment from a doctor. If you suspect CIRS or any other illness, contact a healthcare professional.