Understanding Mould Illness: Why There Is No One-Size-Fits-All Approach
- Muriel Wallace-Scott
- Sep 20
- 5 min read
What We Mean by “Mould Illness”
At The Autoimmune Clinic we are not referring to a small patch of mildew on a bathroom sealant, although that should still be cleaned and the cause of damp addressed. The clinical picture we see most often is linked to significant, ongoing water damage within a building. Examples include a slow pipe leak under flooring, a compromised damp-proof course, a roof leak that intermittently wets the loft, or condensation behind large furniture such as wardrobes.
These events create conditions for hidden mould growth and microbial amplification behind walls, subfloors, and voids. The result can be a continuous release of spores, fragments, microbial volatile organic compounds (mVOCs)and biotoxins into indoor air.
Sometimes, a few visible spots are the tip of the iceberg, and sometimes a home can appear spotless while the air and dust carry significant mould particles from a hidden source. Thorough investigation is key to knowing whether exposure is significant and impacting health.
Different Types of Reactions to Mould
Not all mould-related illness looks the same. Two people can live in the same house and one might become very unwell while the other is unaffected. Responses depend on genetics, immune regulation, detoxification capacity, overall toxic burden, and life stressors.
1) Mould Allergy (IgE-Mediated)
This is a classical allergy response involving mast cell degranulation and histamine release.
Typical features include:
Sneezing, nasal congestion, itchy eyes and sinus irritation
Wheeze, cough, or asthma-like symptoms
Skin rashes, hives, eczema flares
Sudden fatigue, brain fog or palpitations when exposed
First steps: Discuss mould allergy testing with your GP or arrange private specific IgE and total IgE testing. Saline nasal rinses and optimising air quality at home can provide relief while a longer-term plan is put in place.
2) Mould Sensitivity (IgG-Mediated and Non-IgE Immune Activation)
This pattern is more delayed and can be harder to pinpoint. You may feel well for the first 48–72 hours in a damp Airbnb and only then notice worsening fatigue, pain, or cognitive slowing.
Mechanisms may include:
Non-IgE immune pathways triggering inflammation
Cytokine and complement activation
Irritation from mould fragments and microbial toxins
Because exposures at home or work are often continuous, symptoms can blend into the background and be harder to attribute. A careful exposure history combined with IgG mould sensitivity testing (where appropriate) can be helpful.
3) Immune Dysregulation & Total Body Burden
A mouldy environment adds to the total load on your body. If your detoxification capacity, stress levels, sleep, or nutrient status are already compromised, mould may be the final straw that tips you into persistent inflammation.
Reducing background stressors – optimising diet, improving sleep quality, moderating toxic exposures, and supporting detoxification – can often help reduce the immune system’s hyper-reactivity and allow recovery.
CIRS is a complex, genetically influenced condition where the immune system fails to recognise and clear mould-related biotoxins. Those with susceptible HLA-DR haplotypes may live in a mouldy home for years without major symptoms – until a trigger such as infection, surgery, or severe stress dysregulates the immune response.
Symptoms can include:
Persistent fatigue
Widespread pain and stiffness
Cognitive changes (“brain fog”)
Sleep disturbance, mood changes or anxiety
Hormonal changes, weight shifts
Increased sensitivity to foods, chemicals, smells, and even light or sound
Because two people in the same house can be affected differently, symptoms should not be dismissed based on other family members’ health.
When CIRS is suspected, a structured, stepwise approach is often needed. This may include environmental assessment and remediation, binders to reduce biotoxin recirculation, and immune-modulating strategies, guided by a practitioner experienced in this field.
What First Steps Can You Take?
Even before a full investigation, there are practical things you can do:
Remove or reduce exposure: Address leaks, improve ventilation, move furniture away from cold walls, use extractor fans, and consider professional assessment or remediation if the source is significant.
Lower your overall toxic burden: Minimise chemicals in your home environment, choose natural cleaning and skincare products, and prioritise whole, minimally processed foods.
Support detoxification pathways: Ensure good hydration and regular bowel movements. Gentle sweating (through exercise or sauna, if tolerated) may support natural detoxification.
Regulate the immune system: Focus on the foundations – restorative sleep, nervous system regulation, stress management, and gentle, tolerable movement.
If You Are Seeing a Histamine-Type Response
If mould exposure triggers flushing, itching, hives, or other histamine-type reactions, there are strategies to help stabilise mast cells and reduce reactivity. These can include calming the nervous system, reducing dietary histamine load temporarily, and exploring natural or prescribed mast cell stabilisers under professional guidance.
Testing Options
Because mould-related illness can present in many ways, it is worth starting with a general health MOT – including basic blood work through your GP or privately – to assess inflammation markers, immune function, and metabolic health.
Additional investigations to consider include:
Allergy testing: Specific IgE with total IgE where allergic symptoms are present
Mould sensitivity testing: IgG testing in the right clinical context
CIRS-specific screening: Symptom cluster questionnaire and VCS (visual contrast sensitivity) testing
Comprehensive CIRS panel: Where indicated and appropriate
Environmental testing: Professional assessment of the home (IEP inspection) or targeted air/dust sampling
There Is No Single Solution or One Approach for All
The take away here is that mould illness is highly individual. The right approach depends on the mechanism driving your symptoms, your genetics, the severity of exposure, and your overall resilience. For some, simple exposure reduction and lifestyle changes are enough to bring significant relief. For others, particularly those with CIRS, a more comprehensive, carefully paced plan is needed.
How We Can Help?
If you are experiencing persistent fatigue, brain fog, pain, hormonal disruption, sleep disturbance or heightened reactivity to foods, chemicals or smells, and you suspect mould may be contributing, we can help.
At The Autoimmune Clinic we will:
Take a detailed history to explore your exposure and symptom patterns
Guide you on appropriate next steps for medical evaluation and home assessment
Support your immune regulation and detoxification pathways through personalised nutrition and lifestyle strategies
Create a tailored roadmap that addresses both your internal health and your environment
Our clinic director, Muriel Wallace-Scott, is a Shoemaker Proficiency Partner and has undertaken extensive training with a wide range of educational resources in mould illness, immune dysregulation, and environmental medicine.
Muriel’s approach is not protocol-driven and never assumes that one method will work for everyone. Instead, she works collaboratively with clients, adapting her support based on each individual’s history, physiology, environment, and tolerance. This ensures a highly personalised, step-by-step plan that meets you where you are and moves at a pace that feels safe and sustainable.
