Is Toxic Mould Making You Sick? Understanding Chronic Inflammatory Response Syndrome (CIRS)

Most people think of mould as a bit of surface grime — something a quick scrub or spray can fix. But for some, mould exposure becomes far more than a household nuisance. It can quietly trigger a cascade of health issues that no amount of cleaning, medication, or rest seems to solve.

If you’ve been struggling with unexplained fatigue, brain fog, sinus pressure, muscle pain, or worsening asthma, and can’t quite pinpoint why — your environment could be playing a bigger role than you realise.

That’s because long-term exposure to mould and the toxins it produces can, in some people, set off a condition known as Chronic Inflammatory Response Syndrome (CIRS) — a complex immune reaction that affects multiple systems in the body. Unlike a simple mould allergy, CIRS keeps the body in a state of constant inflammation, even long after you’ve left the contaminated space.

In this article, we’ll explore what CIRS actually is, how toxic mould exposure can trigger it, the signs to look out for, and what steps you can take if you suspect mould might be making you sick.

What is Chronic Inflammatory Response Syndrome (CIRS)?

Chronic Inflammatory Response Syndrome (CIRS) is a complex condition that occurs when the body’s immune system becomes overwhelmed by ongoing exposure to certain environmental toxins — most commonly from mould in water-damaged buildings.

Under normal circumstances, when we encounter mould or other irritants, the body’s innate immune system (our first line of defence) recognises the threat and removes it. Once the danger passes, the immune system “stands down,” allowing inflammation to settle.

However, for some people — particularly those with specific genetic susceptibilities (known as HLA-DR gene types) — this process doesn’t work properly. Their immune systems are unable to recognise and eliminate mould toxins (mycotoxins) efficiently. Instead of clearing the toxins, their bodies continue to perceive them as a threat, keeping the immune system switched on indefinitely.

This constant “red alert” state leads to a chronic inflammatory cascade throughout the body. Inflammation becomes widespread, not just in the sinuses or lungs, but across multiple systems — affecting the nervous system, endocrine system, gut, and even cellular energy production.

At the cellular level, mould toxins can bind to receptors and interfere with mitochondrial function — the part of our cells responsible for producing energy (ATP). When this happens, energy production drops, and the body begins to experience symptoms like fatigue, brain fog, and muscle weakness.

At the same time, inflammatory messengers known as cytokines are released in excess. These chemicals trigger further inflammation, disrupting hormones, sleep patterns, mood, and immune balance. Over time, this results in the multi-system picture that defines CIRS — a body stuck in a loop of inflammation, unable to “reset” itself.

According to environmental medicine expert Dr Neil Nathan in a podcast, mould toxicity isn’t simply an allergic reaction to spores; it’s a biochemical disruption that affects the body at a cellular and immune level. The immune system, in trying to protect you, ends up harming you instead — keeping inflammation alive even after you’ve left the contaminated environment.

What makes CIRS especially tricky to recognise is how broad and variable its symptoms can be. The effects can range from subtle cognitive changes to severe physical exhaustion — which is why so many people go undiagnosed for years.

What are the common symptoms of CIRS?

One of the reasons Chronic Inflammatory Response Syndrome (CIRS) often goes unrecognised is because its symptoms can be so varied — and often mimic other conditions. What starts as fatigue or sinus pressure can gradually progress into brain fog, anxiety, or even hormonal imbalances. Because these symptoms appear unrelated, many people spend years seeking answers before discovering that mould exposure is the common thread.

CIRS can affect multiple systems at once — the immune system, brain, hormones, gut, and respiratory tract — creating a complex web of symptoms that can fluctuate day to day.

CIRS symptom clusters

Because CIRS can impact nearly every area of the body, experts such as Dr Ritchie Shoemaker have grouped symptoms into clusters to help identify patterns. His research identified more than 35 recognised symptoms that fall into 13 key clusters.

If a person experiences symptoms from eight or more clusters, the likelihood of CIRS is considered very high (over 95%).

Below is a simplified overview of these symptom clusters:

Note: Not everyone with CIRS will experience all of these symptoms. However, having multiple symptoms across different clusters — especially when they worsen in damp or mouldy environments — is a strong indicator that mould-related inflammation may be contributing to your health concerns.

If you’ve been experiencing a combination of these symptoms — particularly if they improve when you’re away from home or work — mould exposure and CIRS may be worth exploring with a healthcare provider.

How mould triggers chronic inflammation

What makes mould truly harmful isn’t always visible. It’s the tiny, invisible particles it releases into the air — spores, fragments, and toxins known as mycotoxins — that can trigger a powerful immune reaction once inhaled or absorbed through the skin.

In a healthy body, the immune system identifies these particles as foreign invaders, neutralises them, and clears them out. The inflammation that occurs is part of a normal, short-term healing process. Once the threat is gone, the immune system switches off, and the body returns to balance.

However, for some people, that “off switch” doesn’t work properly.

When the immune system can’t turn off

In individuals who are genetically susceptible — particularly those with specific HLA-DR gene variations — the immune system struggles to recognise and eliminate mould toxins. These biotoxins can’t be efficiently broken down by the liver or cleared from the bloodstream, meaning they circulate continuously through the body.

Because the immune system keeps detecting the toxins but can’t remove them, it stays in permanent defence mode, releasing inflammatory messengers called cytokines over and over again. This chronic inflammation damages tissues, disrupts hormone regulation, and interferes with normal cell function — even long after the original exposure has stopped.

How doctors identify CIRS

Because Chronic Inflammatory Response Syndrome (CIRS) affects so many systems of the body, it can easily be mistaken for other illnesses — from chronic fatigue syndrome to depression or autoimmune disorders.
That’s why proper diagnosis requires a multi-step approach, combining symptom history, environmental assessment, and targeted lab testing.

If you’ve been feeling unwell for a long time and suspect mould exposure could be playing a role, it’s important to work with a doctor who understands environmental and functional medicine, as CIRS isn’t yet widely recognised in conventional healthcare.

1. Environmental history and exposure assessment

Diagnosis usually begins with looking at your environment — particularly your home or workplace.

Doctors might ask about:

• Past or current water damage, leaks, or flooding
  
• Musty odours or visible mould growth
  
• Time spent in environments where symptoms worsen (e.g. damp basements, older offices)
  
• Improvement when away from those environments

If mould is suspected, professional indoor air testing or surface sampling can help identify species known to produce mycotoxins (like Stachybotrys, Aspergillus, or Penicillium).

For a more accessible option, you can also use an at-home mould test kit, such as those from SAN-AIR, which allow you to collect water, air or surface samples from your home environment. Once collected, these samples can be sent to a laboratory for analysis (such as Mycolab/Mycotec or Eurofins) to confirm the type and concentration of mould present.

Buy SAN-AIR™ Mould & Bacteria Test Kit at Aussie Pharma Direct

Read related article: How to Use the SAN-AIR Mould & Bacteria Test Kit: A Step-by-Step Guide

2. Symptom clusters and clinical screening

Some doctors use the CIRS symptom cluster model to cross-check for symptoms. If a patient reports symptoms in eight or more of the 13 clusters, CIRS is highly likely.

To support this, a Visual Contrast Sensitivity (VCS) test — a simple, non-invasive online or in-office assessment — can detect early signs of neurological inflammation caused by toxin exposure.

3.  Laboratory testing

Specific blood markers can help confirm the presence of systemic inflammation and immune dysregulation. Commonly used tests include:

• TGF-β1, MMP-9, and C4a: Indicators of chronic immune activation and inflammation.
  
• VEGF (Vascular Endothelial Growth Factor): Often low in CIRS, reflecting poor oxygen delivery to tissues.
  
• MSH (Melanocyte-Stimulating Hormone): Typically low, contributing to fatigue, sleep issues, and hormonal imbalance.
  
• ADH/osmolality ratio: Can help explain symptoms like excessive thirst or frequent urination.

These lab results, when combined with a history of exposure and symptoms, give a clearer picture of how mould-related inflammation is affecting the body.

4. Differential diagnosis

Because CIRS shares similarities with other conditions, doctors may also rule out:

• Thyroid disorders
  
• Chronic fatigue syndrome (ME/CFS)
  
• Fibromyalgia
  
• Autoimmune conditions
  
• Depression or anxiety disorders (when physical inflammation is the underlying driver)

This ensures that treatment targets the true cause — rather than just managing symptoms.

5. Confirming the source

Finally, addressing the environmental trigger is crucial. Even the best medical treatment won’t be effective if exposure to mould continues. Testing and remediating the affected space — or temporarily relocating — is often the first real step toward recovery.

Steps to take if you suspect CIRS

If you’ve been experiencing persistent, unexplained symptoms that seem to worsen in certain environments — especially damp or musty ones — it’s important to take action early. 

Step 1: Identify and eliminate the source of exposure

Start by investigating your surroundings. Look for signs of water damage, musty odours, or visible mould growth in areas such as bathrooms, laundries, and behind furniture. If you rent or work in a shared space, notify your landlord or employer as soon as possible — mould in the building’s structure needs professional remediation.

If you suspect hidden mould, use an at-home mould test kit to collect samples from the air or surfaces. These samples can then be sent to a laboratory to confirm how severe the contamination is.

Once confirmed, proper cleaning and environmental remediation are essential. Avoid simply painting over or bleaching mould — this only hides the problem temporarily and can worsen indoor air quality. Instead, use targeted products designed to kill mould spores and prevent regrowth, such as SAN-AIR’s Mould Remover and Prevention range, and ensure good ventilation throughout your home.

If you’re planning to tackle the issue yourself, you can safely do so provided the contamination isn’t extensive and the source of moisture is manageable. Just be sure to wear proper personal protective equipment (PPE) — including gloves, goggles, and a respirator mask — to avoid inhaling spores or coming into contact with cleaning chemicals. 

You can find practical tips on how to test, clean, and prevent mould growth effectively in our homeowner’s guide using SAN-AIR products here.

However, if the mould problem appears to stem from structural damage — such as leaks within walls, ceiling water ingress, or damp subfloors — it may indicate a larger infestation that requires professional help. In these situations, hiring a qualified mould testing and remediation specialist is the safest choice to ensure the contamination is completely and safely removed. This is especially important if you or anyone around you have pre-existing respiratory conditions that may worsen if you take on the remediation work yourself.

Read related article: Who to Call for Mould Problems: The Experts You Need for Every Type of Mould Issue

Step 2: Improve indoor air quality

CIRS recovery is heavily dependent on clean, low-toxin air.

• Use air purifiers with HEPA and activated carbon filters to reduce airborne spores and allergens.
  

• Maintain humidity between 40–50%, as mould thrives in moisture.
  

• Open windows when weather allows, and use exhaust fans in high-humidity areas like bathrooms and kitchens.

Step 3: Support your body’s recovery

Once exposure is under control, focus on helping your body recover. Start gently — the goal is to reduce inflammation and rebuild resilience rather than “detox” aggressively.

• Stay hydrated and prioritise restful sleep.
  
• Eat an anti-inflammatory diet rich in vegetables, lean proteins, and healthy fats.
  
• Light movement and stress-reduction techniques (like breathing exercises or yoga) can help calm the nervous system, which often becomes overactive in CIRS.

If your symptoms are severe or long-lasting, seek guidance from a healthcare professional experienced in environmental medicine or CIRS treatment. They can recommend tailored therapies, including binders or supplements, to support your immune and detox pathways safely.

Step 4: Prevent future exposure

After remediation, prevention is the next important step you need to do.. Regularly check for leaks, maintain ventilation, and use preventative treatments like SAN-AIR’s mould prevention reactive gels, which helps inhibit airborne mould spores before they settle and grow.

Check out our guide: Weekly Checklist to Keep Your Home Mould-Free

Conclusion: Healing starts with awareness

Chronic Inflammatory Response Syndrome (CIRS) shows us just how powerful environmental exposure can be, turning what begins as a mild irritation into a whole-body inflammatory response.

The good news is that CIRS is recognisable, manageable, and treatable once the underlying cause is understood. Identifying and addressing the source of mould exposure is the first and most important step, followed by supporting your body’s natural recovery through rest, nutrition, and medical guidance where needed.

By paying closer attention to your indoor environment — testing when necessary, maintaining ventilation, and keeping mould under control — you can help reduce the risk of inflammation and protect your overall wellbeing.

Take the next step toward a healthier home

At Aussie Pharma Direct, we’re committed to helping Australians breathe cleaner, healthier air. Explore our range of SAN-AIR’s mould removal and prevention products and helpful guides on mould testing, remediation, and indoor air care, our goal is to make it easier for you to create a safe, low-toxin living space.