Mold Exposure and Chronic Fatigue: What Clinical Studies Reveal

Can mold exposure contribute to persistent fatigue? Research suggests a possible connection between indoor dampness, mold-derived substances, and chronic fatigue. Although the evidence is still developing, several human studies have investigated whether mold exposure may contribute to immune changes, inflammation, and symptoms associated with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

How Might Mold Exposure Contribute to Fatigue?

Mold grows in damp environments and can release spores, fungal fragments, allergens, and mycotoxins. Researchers are investigating several potential mechanisms linking these exposures to fatigue:

• Immune activation: Certain fungal components can stimulate immune responses and inflammatory signaling.
• Inflammation: Immune mediators may influence energy levels, sleep, and cognitive function.
• Mitochondrial function: Researchers have proposed that some mycotoxins could affect cellular energy production, although this has not been established as a cause of mold-associated fatigue in humans.
• Respiratory and sleep disturbances: Mold-related allergies, congestion, and asthma can interfere with sleep and contribute to exhaustion.

These mechanisms are biologically plausible, but their role in persistent fatigue following typical indoor mold exposure remains uncertain.

What Do Clinical Studies Show?

1. Mold Exposure and Fatigue: Systematic Review (2025)

Dooley M, McMahon SW. Fatigue and exposure to mold and/or dampness: A systematic review of the literature from 2011–2018. Environmental Analysis Health and Toxicology. 2025;40(3).

This review examined six studies, including research involving more than 40,000 participants. The authors found evidence of an association between indoor dampness or mold exposure and fatigue, although the strength of evidence varied.

Key takeaway: Indoor environmental conditions may be relevant when investigating persistent fatigue, but observational studies cannot establish that mold directly causes it.

Read the study

2. Mycotoxins in Patients With Chronic Fatigue Syndrome (2013)

Brewer JH, et al. Detection of mycotoxins in patients with chronic fatigue syndrome. Toxins. 2013;5(4):605–617.

Researchers tested urine samples from 112 patients diagnosed with chronic fatigue syndrome. They reported detectable levels of at least one tested mycotoxin in approximately 93% of participants, and more than 90% reported current or previous exposure to water-damaged buildings.

The authors proposed that mold-derived compounds could be relevant to some patients with chronic fatigue and discussed possible effects on cellular energy production.

Important limitation: This study did not establish that mycotoxins caused the patients' symptoms. The absence of a concurrently recruited control group and limitations of the testing methods make the findings preliminary. Urinary mycotoxin results alone cannot establish illness caused by indoor mold.

Read the study

3. Mycotoxins, Mold Components, and Human Health (2024)

Hurraß J, et al. What effect do mycotoxins, cell wall components, enzymes and other mold components and metabolites have on our health? Allergo Journal International. 2024;33:124–132.

This review examines mycotoxins, fungal cell-wall components, allergens, and other microbial substances associated with damp buildings. Laboratory and animal studies suggest that some of these substances can influence immune responses and inflammatory pathways.

However, the clinical significance of typical indoor exposures remains incompletely understood, and the review does not establish that mold causes chronic fatigue syndrome.

Read the review

4. New NIH-Funded Research on Mold Exposure and ME/CFS (2026)

Nova Southeastern University announced a $3 million NIH grant to investigate a potential link between mycotoxin exposure and ME/CFS. The planned research will examine more than 200 participants and explore relationships between mycotoxin exposure, symptom severity, and immune-system changes.

Why it matters: This research may help clarify whether particular environmental exposures contribute to biological changes in some patients with ME/CFS. The project is ongoing, so its findings are not yet available to establish causation.

Read the research announcement

What Should You Do if You Suspect Mold-Related Fatigue?

If fatigue began or worsened after exposure to a damp or water-damaged building, consider:

• Investigating the environment: Address leaks, persistent moisture, and visible mold.
• Evaluating other causes of fatigue: Iron deficiency, thyroid disorders, sleep problems, nutritional deficiencies, and other medical conditions can produce similar symptoms.
• Assessing symptoms comprehensively: Fatigue accompanied by cognitive difficulties, unrefreshing sleep, or worsening symptoms after exertion may warrant further evaluation.

There is currently no single validated blood or urine test that proves mold exposure is the cause of chronic fatigue. Testing results should be interpreted cautiously and in the context of a person's symptoms and exposure history.

Conclusion

Published studies suggest an association between indoor dampness, mold exposure, and fatigue. Preliminary research has also identified mycotoxins in some patients with chronic fatigue syndrome, while laboratory studies suggest potential effects on immune function and inflammatory signaling.

However, current evidence does not establish that mold exposure or mycotoxins directly cause ME/CFS. Further research is needed to identify which exposures may be clinically significant and whether certain individuals are more susceptible.

Investigating environmental exposure alongside other potential causes of fatigue offers a balanced, evidence-informed approach.

CONTACT VALLEY INTEGRATIVE HEALTH TODAY

Devin Wilson, ND, is a licensed Naturopathic Doctor and owner of Valley Integrative Health, LLC, in Ashland, Oregon. With over a decade of clinical experience, including two years of training with a physician affiliated with Johns Hopkins and Yale, Dr. Wilson integrates naturopathic and modern medical approaches with selected advanced therapies. His enduring goal is to help people re-establish, maintain and optimize their health using a patient-centered and holistic approach.

References

1. Dooley M, McMahon SW. Environ Anal Health Toxicol. 2025;40(3). https://doi.org/10.5620/eaht.2025018
2. Brewer JH, et al. Toxins. 2013;5(4):605–617. https://doi.org/10.3390/toxins5040605
3. Hurraß J, et al. Allergo J Int. 2024;33:124–132. https://doi.org/10.1007/s40629-024-00295-8
4. Nova Southeastern University. NIH-funded research announcement, 2026. https://news.nova.edu/uncategorized/nih-awards-nsu-researchers-3-million-to-study-potential-link-between-mold-exposure-and-myalgic-encephalomyelitis-chronic-fatigue-syndrome/

This article is for educational purposes and is not a substitute for individualized medical evaluation.