What is Mold-Illness?
Chronic exposure to mold and its by-products is increasingly recognized as a potential contributor to long-standing health symptoms. Mold (fungi that grow in damp, humid conditions) can release tiny spores and secondary metabolites (mycotoxins) which may trigger persistent inflammation, alter immune function, and contribute to a variety of poorly-explained symptoms.
Often overlooked, mold-related illness is best approached as an environmental health issue: if you’ve been exposed to damp or water-damaged buildings, hidden leaks, or musty air, recognizing the link between your environment and your health may be a significant step toward improvement.
What is Mold and Why Does It Matter?
Molds are fungi that thrive in moist, warm, poorly ventilated spaces. They are common in bathrooms, kitchens, basements, behind drywall, under carpets, and in buildings affected by flooding or leaks. When mold grows, it releases microscopic spores and various compounds that may travel through the air. These spores, fragments of hyphae (the fungal filament structures), and mycotoxins are the main ways mold can impact health (1).
A key point: the health concern is not just visible black patches of mold, but hidden dampness and prolonged exposure, which allow mould to colonize and produce bioactive substances. Some of these substances—mycotoxins—can cause cellular and systemic effects (2).
How Does Mold Exposure Affect the Body?
Mold exposure can influence health through several overlapping mechanisms:
Allergic/hypersensitivity reactions: mold spores may act as allergens, causing sneezing, runny nose, itchy eyes, and asthma exacerbations (3).
Toxic or inflammatory responses: mycotoxins and microbial fragments may trigger innate immune activation, oxidative stress, and dysregulation of immune or nervous system function (4).
Structural and barrier disruption: some studies suggest mold-derived toxins or fungal fragments may impair epithelial barriers, including in the gut or lungs, or even the blood-brain barrier, allowing further systemic effects (5).
Because of this, the symptoms are often multi-systemic, vague, and chronic, which makes the diagnosis and management challenging.
Common Symptoms of Mold-Related Illness
Symptoms vary from person to person, influenced by the degree of exposure, individual susceptibility (e.g., immune-compromised or pre-existing lung disease), and environmental factors. Some of the commonly reported signs include:
Respiratory: chronic congestion, sinusitis, wheezing, shortness of breath, cough (6).
Neurological/cognitive: brain fog, difficulty concentrating, memory issues, dizziness, mood changes (anxiety, depression) (7).
Gastrointestinal: bloating, cramps, nausea, diarrhea (8).
Musculoskeletal: joint aches, muscle soreness.
Immune/hypersensitivity: increased sensitivity to foods or chemicals, recurrent infections, fatigue.
Skin and general: rashes, hives, unexplained bruising or bleeding, headaches, poor sleep.
Who is at Greater Risk?
Certain individuals are more vulnerable to mold-related health impacts:
People with asthma, chronic obstructive pulmonary disease (COPD), or other lung conditions
Those with immune compromise (e.g., immunosuppression, chronic illness)
Infants, children, the elderly
People living or working in buildings with known water damage, flooding, or persistent dampness
Those with genetic or other predispositions affecting detoxification or immune regulation
What To Do: Practical Steps for Prevention & Support
1. Identify and Eliminate the Source
The most effective intervention is reducing ongoing exposure. This typically means:
Inspecting for visible mold, damp spots, leaks, high humidity, and condensation
Hiring a professional mold remediator if extensive growth is found
Using de-humidification, improving ventilation, and reducing moisture load in bathrooms/basements
Replacing water-damaged drywall, carpets, insulation, and other building materials as needed
2. Improve Indoor Air Quality
Use HEPA-grade air filters and clean HVAC systems
Monitor indoor humidity (ideal < 50 %)
Ensure regular cleaning of dust, especially in areas behind furniture, ducts, and ceilings
3. Support Health & Detoxification
While the evidence is not definitive, many practitioners recommend supportive steps such as:
Maintaining hydration, good nutrition, and supporting gut health and the microbiome
Anti-inflammatory diet, low in processed foods, and potential reduction of high-histamine foods if mast-cell activation is suspected
Supporting sleep, reducing stress, increasing gentle movement and lymphatic drainage
Working with a health practitioner experienced in environmental medicine if symptoms persist
Mycotoxin & Home Mold Testing
Mycotoxin Testing
Mycotoxins are toxic compounds produced by certain molds. Testing for mycotoxin exposure is offered in some clinics and labs across Ontario. Testing for mycotoxins (such as trichothecenes, aflatoxins, ochratoxins and gliotoxin) when prolonged symptoms of mold exposure are suspected may be indicated.
Important to consider:
Mycotoxin testing is not covered by standard health insurance and its clinical utility (for diagnosing mold-related illness) remains debated in conventional medicine.
A positive mycotoxin test does not by itself establish causation of symptoms; it must be interpreted in the context of exposure history, symptoms, and other diagnostics.
Focus should remain on eliminating exposure first; testing is adjunctive, not primary, unless guided by a qualified clinician.
Home Mold Testing
For assessing potential indoor mold contamination in Ontario, here are relevant points:
According to Health Canada and provincial guides, visible mold, water damage or musty odours warrant investigation and remediation rather than relying solely on air-sampling tests.
Several private inspection services in Ontario (e.g., in Toronto and the GTA) offer comprehensive mould inspection/testing services: visual inspection, moisture mapping, air monitoring, surface or bulk sampling.
Home-owner tips:
If you see visible mould growth or smell musty odours, start with identifying and fixing the moisture source (leaks, condensation, humid basement) rather than immediately jumping to extensive testing.
Use a certified mold inspection service if you suspect hidden growth (behind walls, under flooring) and occupants have unexplained symptoms.
When engaging a testing service, ask: what types of samples (air, surface, bulk) will be collected? What standards will be used? What are the next steps if mold is confirmed?
Keep in mind: testing results are only helpful if followed by effective remediation and moisture control. Testing alone doesn’t solve the problem.
Disclaimer: This information is for educational purposes only and is not intended to provide or replace medical advice, diagnosis, or treatment. Always consult your qualified healthcare provider for individualized recommendations.