Mold illness: symptoms, diagnosis, and why it’s so often missed

Mold illness is real — and one of the most frequently missed pieces in complex, “we’ve tried everything” cases. Here are the fundamentals: what it is, how it shows up in the body and mind, and why it’s so often mistaken for something else.

Key takeaways
Mold illness (CIRS) is an illness, not an allergy — an inflammatory response to mycotoxins from water-damaged environments.
Over a quarter of U.S. buildings are estimated to have water damage.
Symptoms are both physical (fatigue, aches, GI, respiratory) and cognitive (brain fog, memory, mood).
It's commonly mislabeled as fibromyalgia, chronic fatigue, MS, or “stress” — worth considering when the picture doesn’t add up.
In this article
I. What is mold illness?
II. Mold, spores & mycotoxins
III. Symptoms: physical & cognitive
IV. Why it’s so often misdiagnosed
V. Common questions

Mold illness, a condition also known as Chronic Inflammatory Response Syndrome (CIRS), has become increasingly recognized in recent years. This article explores the fundamentals of mold illness, including the role of mold, mold spores, and mycotoxins.

We will also delve into the symptoms associated with mold illness, both physical and cognitive, and shed light on the challenges of accurate diagnosis.

What is mold illness?

Mold illness, or Chronic Inflammatory Response Syndrome (CIRS), is an illness that often arises following significant exposure to a water-damaged environment. While the degree of exposure may vary among individuals, even short or repeated exposures can have adverse effects.

Over a quarter of buildings in the United States are estimated to suffer from water damage, providing a breeding ground for mold growth. This can lead to various symptoms and chronic health issues for susceptible individuals.

Mold, spores & mycotoxins

Mold: the culprit in the shadows

Molds are fungi that exist both indoors and outdoors. With tens of thousands to potentially hundreds of thousands of mold species, these organisms thrive in environments with moisture. When exposed to damp conditions, molds reproduce by releasing mold spores into the air, seeking new surfaces to colonize and digest. Moisture control is crucial in preventing mold growth, as mold can survive on various surfaces as long as moisture and oxygen are present.

Mold spores: tiny carriers of trouble

Mold spores are microscopic cells that float in the air, both indoors and outdoors. They are hardy and can survive in dry and harsh environments where mold itself may struggle. When these resilient spores land on a surface with moisture, they can initiate mold growth and begin deteriorating the material. While completely eliminating mold spores from the environment is impossible, managing moisture is key to preventing their proliferation.

Mycotoxins: the hidden dangers

Mycotoxins are toxic substances produced by molds, present on mold spores and mold fragments. These mycotoxins can easily become airborne and travel through the environment. They can enter the body through inhalation, skin contact, or ingestion of mold-contaminated foods.

Once inside the body, mycotoxins can trigger the production of pro-inflammatory cytokines, which are small proteins involved in immune responses. The inflammatory response caused by mycotoxins can contribute to chronic health issues in susceptible individuals.

Symptoms: physical & cognitive

It’s important to remember mold illness is indeed an illness, not an allergy. There is a long list of symptoms that may arise with this illness. More apparent symptoms of mold exposure include respiratory issues, sneezing, nasal drainage, and skin issues.

Physical symptoms: unmasking mold’s effects

Mold illness can manifest in a wide range of physical symptoms. Some common symptoms include respiratory issues, sneezing, nasal drainage, and skin problems. Prolonged exposure to mold and water-damaged environments can lead to more severe manifestations, such as:

  • Fatigue
  • Muscle aches
  • Joint pain
  • Gastrointestinal disturbances

Identifying these physical symptoms and their correlation with mold exposure is essential for accurate diagnosis and effective treatment.

Cognitive symptoms: mold’s impact on the mind

In addition to physical symptoms, mold illness can affect cognitive function. Research has revealed structural brain abnormalities in individuals with CIRS, including atrophy of specific brain regions and enlargement of others. Cognitive symptoms commonly associated with mold illness include memory problems, difficulty concentrating, brain fog, and mood disturbances. Recognizing the cognitive impact of mold illness is crucial for the comprehensive evaluation and management of affected individuals.

Why it’s so often misdiagnosed

Patients often present with many bizarre symptoms that practitioners (or even family members) believe are all “in their head.” Other times, practitioners misdiagnose mold illness. In a 2013 study of 112 patients with chronic fatigue syndrome, 104 (93%) tested positive for at least one mycotoxin.

When compared to healthy control subjects, researchers found mycotoxin levels were significantly elevated in patients with chronic fatigue syndrome (6). It’s imperative to consider mold when looking for a root cause in complex patient cases.

Like the patients with chronic fatigue syndrome, patients are often given various diagnoses that are either incorrect, or if they are correct, they often improve once they are treated for mold. These diagnoses include:

  • Fibromyalgia
  • Chronic Fatigue Syndrome
  • Multiple Sclerosis
  • Depression
  • Stress
  • Allergy
  • Post Traumatic Stress Disorder
  • Somatization
  • Irritable Bowel Syndrome
  • Attention Deficit Disorder

Recently, some more concrete evidence for neurological difficulties associated with mold illness has been found. In a 2014 study, 17 patients who presented with CIRS showed structural brain abnormalities when compared to a medical control group. These abnormalities included atrophy of the caudate nucleus and enlargement of the pallidum. They also included enlargement of the left amygdala and right forebrain.

There is also research to support the inflammatory cytokine response that mold and mycotoxins induce. These inflammatory cytokines are also present in neurological conditions, such as major depression, which is more reason to test for mold as one of the root causes of neurological issues.

What this may mean
If you’ve collected several diagnoses that never fully explained how you feel — especially with a history of a leaky roof, a flooded basement, or a musty building — mold is one of the pieces worth ruling in or out. It doesn’t mean mold is the answer, only that it’s a reasonable question when the usual explanations haven’t held up.
When to seek medical care
Mold illness overlaps with many serious conditions, so a proper evaluation matters. If you have significant breathing difficulty, a persistent high fever, or rapidly worsening symptoms, seek medical care promptly. For chronic, unexplained symptoms, work with a clinician experienced in evaluating mold exposure alongside other causes.

Common questions

What is mold illness (CIRS)?
Mold illness, also called Chronic Inflammatory Response Syndrome (CIRS), is an illness that often arises after significant exposure to a water-damaged environment. Even short or repeated exposures can have adverse effects in susceptible individuals, leading to chronic health issues.
Is mold illness an allergy?
No. It's important to remember that mold illness is an illness, not an allergy. It involves an inflammatory response driven by mycotoxins, which can affect the whole body — not a classic allergic reaction.
What are the symptoms of mold illness?
More apparent symptoms include respiratory issues, sneezing, nasal drainage, and skin problems. Prolonged exposure can lead to fatigue, muscle aches, joint pain, and gastrointestinal disturbances, as well as cognitive symptoms such as memory problems, difficulty concentrating, brain fog, and mood disturbances.
Why is mold illness so often misdiagnosed?
Patients often present with many varied symptoms that get attributed to other conditions — fibromyalgia, chronic fatigue syndrome, MS, depression, stress, allergy, IBS, and others — or dismissed as being 'in their head.' In one 2013 study of 112 patients with chronic fatigue syndrome, 93% tested positive for at least one mycotoxin, which is why mold is worth considering in complex cases.
References (10) ▾
  1. Preventing Mold-Related Problems in the Indoor Workplace. Occupational Safety and Health Administration, US Department of Labor. https://www.osha.gov/Publications/preventing_mold.pdf
  2. Ratnaseelan AM, Tsilioni I, Theoharides TC. Effects of mycotoxins on neuropsychiatric symptoms and immune processes. Front Cell Infect Microbiol. 2018;8:60. https://pubmed.ncbi.nlm.nih.gov/29556452/
  3. Theoharides TC. Mycotoxins, inflammation, and neuropsychiatric symptoms. Clin Ther. 2018;40(6):903-917. https://pubmed.ncbi.nlm.nih.gov/29880288/
  4. What Is a Water-Damaged Building? Surviving Mold. https://www.survivingmold.com/
  5. Diagnosis of mold illness / CIRS. Surviving Mold. https://www.survivingmold.com/diagnosis
  6. Brewer JH, Thrasher JD, Straus DC, Madison RA, Hooper D. Detection of mycotoxins in patients with chronic fatigue syndrome. Toxins (Basel). 2013;5(4):605-617. https://pubmed.ncbi.nlm.nih.gov/23580077/
  7. Common misdiagnosis in mold illness. Surviving Mold. https://www.survivingmold.com/
  8. Shoemaker RC, House D, Ryan JC. Structural brain abnormalities in patients with inflammatory illness acquired following exposure to water-damaged buildings. Neurotoxicol Teratol. 2014;45:18-26. https://pubmed.ncbi.nlm.nih.gov/24946038/
  9. Neuroinflammation and CIRS: structural and functional findings. National Center for Biotechnology Information (PMC4444319). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4444319/
  10. Inflammatory cytokines in major depression. PubMed. https://pubmed.ncbi.nlm.nih.gov/19150053/
This article is educational and is not medical advice, diagnosis, or treatment. Concerns about mold exposure should be evaluated with a qualified practitioner.
Symptoms that started after a move, a flood, or a renovation?

Mold is one of the most missed pieces in complex cases. If your history points there and no one has looked, we investigate it as part of the whole picture.

Request a Consultation