Can Mold Cause Chronic Fatigue Syndrome? Is Mold a “Breakthrough” or Just a False Lead?


By Richard Podell, MD, MPH

When we talk with Chronic Fatigue Syndrome patients, we learn that before they became ill, some were exposed to water-damaged buildings (WDB) or other mold sources. This raises two questions:

1. Are people with CFS more likely to have been exposed to WDB or mold than are healthy persons?

2. If we reduce a CFS patient’s mold burden, would this improve their symptoms?

We can’t answer either question definitively yet. But, both questions are highly relevant––especially the first. One reason is the commercial availability of a new test that measures the amount of mold toxin (mycotoxin) in a person's urine.

Dr. Joseph Brewer, an infectious disease specialist from St. Louis, addressed the first question. Dr. Brewer reports that chronic fatigue syndrome patients are much more likely than healthy people to have mold toxin in their urine. This suggests that mold exposure might be an important causal contributor to CFS.

Dr. Brewer studied 112 patients all of whom met the Center for Disease Control’s 1994 criteria for Chronic Fatigue Syndrome. Using RealTime Lab’s urine test for a panel of three mycotoxins, Brewer found that 94% of his CFS patients had at least one kind of mycotoxin detected in their urine. Most importantly, these patients were NOT selected because they were already known to have a history of mold or WDB exposure. They were selected to study only because they had presented with CFS. However, as it turned out, 90% of these patients did have exposure to a water damaged building.

But, wait! Might many healthy people also have mold toxins in their urine? Dr. Brewer did not recruit healthy controls to compare with his patients. Instead he relied on an earlier study done by RealTime Laboratories. RealTime tested 51 healthy persons who had no history of exposure to water damaged buildings. Among these not even one tested positive for mycotoxins.

My thoughts: The validity of RealTime's study is critical.

If this "stand in" for a control group reasonably represents the general population, then Dr. Brewer's finding that almost all CFS patients had mold toxin in their urine strongly supports a causal connection between mold exposure in this illness. Therefore, it is a critical priority to confirm or deny RealTime's report that healthy people rarely have mycotoxin in their urine.

Others are skeptical. The Center for Disease Control and several “mainstream” environmental specialists I spoke to doubt the usefulness of urine mycotoxin testing. From CDC’s Morbidity and Mortality report:

Low levels of mycotoxins are found in many foods; therefore, mycotoxins are found in the urine of healthy persons. Mycotoxin levels that predict disease have not been established. Urine mycotoxin tests are not approved by FDA for accuracy or for clinical use … Persons using direct-to-consumer laboratory tests that have not been approved by FDA for diagnostic purposes and their health care providers need to understand that these tests might not be valid or clinically useful. Additional information about molds and their health effects is available at

Dr. Brewer understands these issues and welcomes further research that can confirm our deny his findings. 

Dr. Brewer also addressed the second question – Does treating for mold help CFS patients feel better? Brewer treated 151 mycotoxin-positive CFS patients with intra-nasal Amphotericin, a potent anti-fungal agent.

Ninety-four patients of the original 151 tolerated Amphotericin and remained on treatment for six months or more. Among these 88 out of 94 reported an improvement in their symptoms of at least 25%. Twenty-six patients (30%) rated themselves as between 75-100% improved. If confirmed, these are very impressive results. Brewer reported similar benefits with intra-nasal Nystatin.

Sadly, neither of Brewer's treatment trials had a placebo arm. So, we cannot say for sure whether the reported benefits are real.

Perhaps patients told Dr. Brewer what they thought he wanted to hear. Perhaps they felt better because Dr. Brewer took them seriously. Perhaps a placebo effect, etc.

For now, all we can say is that Brewer's results are encouraging but not conclusive. And the mainstream literature is discouraging. For example, patients with chronic sinusitis often have fungal infections. But three double blind studies found that treatment with Amphotericin was no more effective than was using a placebo.

My Bottom Line: Dr. Brewer’s work is strong enough to justify that the CFS-advocacy community invest time and money to do a rigorous controlled study testing whether Dr. Brewer’s potentially critical findings can be reproduced.

I suggest that until more evidence appears:

  1. Dr. Brewer should be praised for his great effort in launching his studies. Doing research from a private practice base is very demanding.

  2. Since there are no proven treatments for ME/CFS and since preliminary evidence favors a role for mold, it’s not unreasonable for CFS patients to consider consulting Dr. Brewer or other “alternative medicine” minded health specialists such as Ritchie Shoemaker, M.D. who have experience treating CFS patients for mold.

  3. BUT be aware that these treatments might or might not in fact be useful. Without better research we cannot know for sure. Mainstream environmental specialists, including the CDC, doubt the clinical value of urine mycotoxin testing.

  4. Evaluation for mold can be expensive. RealTimes Laboratories' urine panel for four mycotoxins costs about $700. Most insurance plans don’t cover it. However, Medicare has started covering the test––if the physician submits a proper set of codes. (Physicians may contact me directly for advice on coding.) Cleaning up a home or office can be extremely expensive. Let the buyer beware.

  5. A controlled study to confirm or refute RealTime Laboratories' and Dr. Brewer’s data should be fairly simple and relatively inexpensive. Therefore, we should all pray that an Angel or the NIH or CDC will be inspired to fund this critical study: Compare the rate of urine mycotoxin and sick building exposure among chronic fatigue syndrome patients with that for appropriate controls. Such a study should quickly decide whether the fungal hypothesis for CFS is or is not truly a breakthrough.

  6. If the fungal hypothesis has merit, it might also affect a broader spectrum of illness. For example, a Spanish research group did autopsies on ten Alzheimer’s patients. They claim to have seen fungus within the brains of all ten. No fungus was seen in the brains of 15 controls. (Additional information can be found on A similar study reported fungus in the brains of patients with ALS (Lou Gehrig’s disease.)

    Dr. Richard Podell Richard Podell, M.D., MPH, is a graduate of Harvard Medical School and the Harvard School of Public Health. He has been treating patients with ME-CFS and Fibromyalgia for more than 20 years.

    A clinical professor at New Jersey's Robert Wood Johnson Medical School, Dr. Podell see patients at his Summit, NJ and Somerset, NJ offices. His website is

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