Mould Illness & CIRS: When the building is the problem

What Mould Illness Actually Is

Mould illness is not an allergy to mould. It is a chronic inflammatory response triggered by biotoxins produced by mould and other organisms that grow in water-damaged buildings. These biotoxins include mycotoxins from mould species like Aspergillus, Stachybotrys, and Penicillium, as well as inflammatory compounds from bacteria and actinomycetes that thrive in damp environments.

In most people, the immune system identifies these biotoxins, tags them for removal, and clears them through the liver and kidneys. The exposure causes temporary symptoms that resolve once the person leaves the building.

In genetically susceptible individuals, roughly one in four people, the immune system cannot properly tag and clear these biotoxins. The toxins recirculate in the body, triggering a chronic inflammatory cascade that does not switch off. The immune system stays activated. Inflammation becomes systemic. Multiple organ systems are affected simultaneously. And because the toxins are not being cleared, the symptoms persist and worsen as long as the exposure continues.

Dr Ritchie Shoemaker’s research established the CIRS framework and identified the specific HLA gene variants that confer biotoxin susceptibility. His work also mapped the inflammatory cascade, including the role of markers like MSH (melanocyte-stimulating hormone), VIP (vasoactive intestinal peptide), MMP-9, TGF-beta 1, and C4a, all of which can be measured to confirm the diagnosis and track recovery.

Why Most Practitioners Miss It

Mould illness presents with symptoms that overlap with dozens of other conditions. Fatigue, brain fog, anxiety, gut dysfunction, hormonal disruption, pain, sensitivity to chemicals and foods, poor temperature regulation, frequent infections. A GP sees these symptoms and tests for thyroid disease, iron deficiency, coeliac disease, and depression. Everything comes back “normal.” The patient is told it is stress, or anxiety, or chronic fatigue syndrome.

A functional medicine practitioner might dig deeper and find gut dysfunction, nutrient depletion, methylation issues, and hormonal imbalance. They treat all of these, and the patient improves temporarily. But the improvements do not hold. The practitioner tries harder. More supplements. More protocols. More restriction. Nothing sticks.

The reason nothing sticks is that the patient is still in the building. You cannot detox your way out of a toxic environment. Every intervention is fighting against ongoing exposure. It is like trying to mop a floor while the tap is still running.

The question that changes everything is not “what is wrong with your body?” It is “what is wrong with your environment?”

Who Is Susceptible

Approximately twenty-four per cent of the population carries HLA gene variants that impair biotoxin clearance. These are identified through a simple blood test (HLA DR/DQ typing). If you carry one of the susceptible genotypes, your body cannot efficiently remove mould toxins, and you are vulnerable to developing CIRS when exposed to a water-damaged building.

This explains why one person in a household can be severely ill while others in the same house are unaffected. It is not psychological. It is genetic. The susceptible person’s immune system cannot clear what the others’ immune systems handle automatically.

It also explains why mould illness can affect entire families differently. I have treated cases where a mother was severely ill, her children were showing signs of immune stress (recurrent infections, dark circles under the eyes, irritability), and her partner was completely unaffected. Same house, same exposure, different genetics.

What Testing Reveals

Mould illness diagnosis requires a combination of environmental assessment and clinical testing.

Mycotoxin testing

measures mould toxins in the urine. This confirms that the body has been exposed to and is accumulating mycotoxins. Elevated levels of ochratoxin A, aflatoxin, gliotoxin, or trichothecenes on a urine mycotoxin panel confirm exposure.

HLA gene testing

identifies whether the patient carries one of the biotoxin-susceptible genotypes. This determines whether the patient’s immune system can clear the toxins effectively.

CIRS inflammatory markers

include MSH, VIP, MMP-9, TGF-beta 1, C4a, VEGF, and ADH/osmolality. These markers map the specific inflammatory cascade that CIRS produces and help differentiate it from other inflammatory conditions.

MARCoNS testing

(Multiple Antibiotic Resistant Coagulase Negative Staphylococci) identifies a specific nasal biofilm infection that is common in CIRS patients and interferes with MSH production. MARCoNS must be treated for full recovery.

Building biology assessment

is essential. A qualified building biologist inspects the property for water damage, measures airborne mould spore levels, checks air conditioning systems, inspects roof spaces and subfloor areas, and identifies sources of moisture. This is not something you can assess visually. Mould grows behind walls, inside air conditioning ducts, in roof cavities, and under carpets. The building can look clean and still be making you sick.

The Recovery Sequence

Recovery from mould illness follows a strict sequence. Skip a step and recovery stalls or reverses.

step 1 Remove yourself from the exposure.

This is non-negotiable. No amount of supplementation, detoxification, or immune support will work while you are still being exposed. If the building cannot be fully remediated (which requires professional mould remediation, not just cleaning), you may need to leave the building. This is the hardest step emotionally and financially, but it is the step that everything else depends on.

step 2 Remove contaminated belongings.

Porous materials that have been exposed to mould (clothing, bedding, soft furnishings, books, mattresses) can harbour mycotoxins and continue the exposure even after you leave the building. A building biologist can advise on what can be cleaned and what needs to be discarded.

step 3 Begin binding and detoxification.

Binders (cholestyramine, activated charcoal, bentonite clay, or chlorella) bind circulating mycotoxins in the gut and prevent reabsorption. This is the first clinical intervention and must happen before immune modulation or aggressive detox protocols.

step 4 Treat MARCoNS.

If nasal biofilm is present, it must be treated to restore MSH production. Specific nasal sprays (BEG spray or alternatives) are used under practitioner guidance.

step 5 Reduce inflammation and support immune regulation.

Anti-inflammatory support, omega-3 fatty acids, glutathione, and targeted nutrients to bring the CIRS inflammatory markers back toward normal. This phase is guided by retesting the specific CIRS markers.

step 6 Restore downstream systems.

Once the biotoxin load is reduced and inflammation is controlled, the gut, hormones, methylation, and other systems that were damaged by the chronic inflammation can be addressed through the standard restoration sequence.

Recovery from CIRS is not fast. It typically takes twelve to twenty-four months for complex cases. But it is thorough. And patients who follow the sequence recover fully in my experience.

The Family Pattern

One of the clearest diagnostic clues for mould illness is the family pattern. When I see a patient whose health has declined and I learn that other family members are also unwell, often with different symptoms, the environment immediately becomes the primary suspect.

I have treated cases where a mother presented with severe fatigue, brain fog, and anxiety. Her children had recurrent ear infections, dark circles under their eyes, behavioural changes, and declining school performance. Her partner had mild seasonal allergy symptoms but was otherwise fine. Same house, same exposure, completely different presentations.

The mother carried HLA susceptibility genes. Her partner did not. Her children had inherited her susceptibility. The partner’s immune system cleared the biotoxins automatically. The rest of the family could not.

This pattern is one of the strongest clinical indicators for environmental investigation. When the whole family is sick, the problem is rarely inside any one person’s body. It is in the environment they share.

I routinely ask about household health patterns in my initial consultation. Questions like “is anyone else in the house unwell?” and “when did you move into your current home?” have led to more diagnoses than any lab test. The answer is sometimes the most important data point in the entire case.

What Standard Medicine Gets Wrong

The most common misdiagnosis I see in mould illness patients is chronic fatigue syndrome, followed by fibromyalgia, anxiety disorder, and “medically unexplained symptoms.” These are not wrong diagnoses in the sense that the symptoms are present. They are wrong in the sense that they describe what is happening without explaining why.

A patient with CIRS will meet the diagnostic criteria for chronic fatigue. Their fatigue is real, severe, and lasting more than six months. But the cause is biotoxin exposure, not an idiopathic fatigue syndrome. Treating the fatigue label with rest, pacing, and energy management addresses the symptom while the patient continues to be poisoned by their environment.

The same applies to the anxiety diagnosis. A CIRS patient with neuroinflammation, disrupted MSH, and altered VIP will experience genuine, severe anxiety. An SSRI may take the edge off. But it does nothing to address the inflammatory cascade driving the neurological symptoms. The anxiety resolves when the biotoxin burden is cleared. It does not resolve when it is medicated over the top of ongoing exposure.

I have also seen patients referred to psychiatrists for symptoms that were entirely environmental. The most concerning pattern is when children are assessed for behavioural disorders or ADHD when the real issue is biotoxin exposure from their school or home. Addressing the environment resolves the behavioural symptoms without medication.

This is why I always ask about the environment, particularly water damage, renovations, and building history, before attributing symptoms to psychological or idiopathic causes. The building is the most commonly missed diagnosis in complex chronic illness.

When to Suspect the Environment

If you recognise any of the following patterns, environmental investigation is warranted.

Your health declined after moving to a new home, starting work in a new building, or renovating your property.

Multiple people in your household are unwell, particularly if children are showing immune stress (recurrent infections, dark circles, irritability, behavioural changes).

Your symptoms do not respond to treatment, or they improve temporarily and then relapse despite continued effort.

You feel better when you travel or stay elsewhere, and worse when you return home.

You have been diagnosed with chronic fatigue, fibromyalgia, or multiple chemical sensitivity without a clear cause.

Your testing shows chronic inflammation (elevated CRP, altered immune markers) without an identifiable source.

You have visible water damage, a history of leaks, or musty smells in your home or workplace.