Can mold cause GI issues? The short answer is: yes. Mold exposure—especially long-term—can seriously harm your gut health. In fact, mold is one of the top root causes of chronic GI issues and other chronic illness symptoms that I see inside my 1:1 practice.
In this article, we’ll break down how mold negatively impacts your digestive system and why it might be worth looking into if you are struggling with mold-related IBS.
Key Takeaways
Mold releases mycotoxins that disrupt gut health, leading to gastrointestinal issues such as bloating, constipation, diarrhea, nausea, vomiting, and leaky gut syndrome.
Mycotoxins compromise the intestinal barrier and alter gut microbiota balance, potentially exacerbating conditions like IBS and IBD.
Mold can also contribute to systemic immune system issues and inflammation in the body — leading to serious health conditions.
Healing from mold and mycotoxin exposure is complex, and takes time, but is possible with a root-cause approach
Mold: The Hidden Root Cause You didn't know about
If you’ve ever lived, worked, or attended school in a water-damaged building, chances are you’ve been exposed to mold. It’s estimated that roughly 47% of US homes have substantial household mold or dampness, with at least 45 million buildings in the US having unhealthy levels of mold. Additionally, 85% of commercial buildings have had past water damage, and 43% of public and private buildings currently have water leaks. If you remember that distinct musty smell in your old college apartment, high school classroom, or workplace, chances are it was mold.
When water damage occurs, mold can begin to grow in as little as 24 to 48 hours if no action is taken to prevent its growth. Most of the time, aside from repairing the leak, little to no further action is taken. As a result, mold silently grows inside and behind your walls, staying hidden while slowly affecting your health.
It’s estimated that up to 50% of all illnesses result from exposure to indoor air pollution, with exposure to water-damaged indoor environments likely being a significant contributor [1].
If you know you’ve experienced significant mold exposure and are also dealing with a host of mysterious symptoms that won’t go away, chances are mold has impacted your health without you even realizing it—especially if the mold was not visible.
One of the tricky things about mold exposure is that it can cause illness long after the time of exposure. People can continue to have elevated mycotoxin levels from past mold exposure even after leaving a moldy environment, making it difficult to identify mold as the root cause. I’ve worked with clients struggling with mold illness years after moving out of moldy spaces, and these environmental exposures are often overlooked.
Mold & Mycotoxins
Mold poses a threat to human health because its spores release harmful microscopic substances called mycotoxins, which are essentially fungal poisons. Mycotoxins are toxic compounds that can be extremely damaging to the human body. These environmental toxins are considered carcinogenic, disrupt our gastrointestinal tract and immune system function, and in some cases, can even be deadly.
Mycotoxins can be either hydrophilic (water-soluble) or lipophilic (fat-soluble). Hydrophilic mycotoxins are absorbed in the GI tract and more easily excreted in the urine, while lipophilic mycotoxins are absorbed into body fat and are not as easily eliminated.
When you inhale air contaminated with high levels of toxigenic mold spores, mycotoxins enter your body fluids and accumulate in your fat cells. With prolonged or high-level exposure, these toxins can cause significant damage to your organs and tissues.
How Mycotoxins Affect Your Digestive Health
Because mycotoxins are easily absorbed in the GI tract, mold exposure can be especially harmful to your gut health and gut permeability. Research shows that mold and mycotoxins can cause serious damage to your gut:
Mold acts like an antibiotic on gut flora, negatively impacting the gut microbiota by reducing beneficial bacteria, lowering microbiome diversity, and hindering important metabolic activities [2, 3].
This disruption in beneficial bacteria can lead to intestinal inflammation, impaired gut barrier function, and an imbalance in the gut microbial community [2].
Exposure to mold and mycotoxins directly affects the balance of bacteria in the gut, kidneys, and urinary tract, and can change the pH of urine, creating ideal conditions for harmful bacterial growth inside the bladder [4].
Mold kills beneficial gut bacteria and encourages pathogenic bacteria to act harmfully by releasing highly inflammatory endotoxins and lipopolysaccharides [5].
Mold weakens gut immune function by reducing mucin production, interfering with cell responses, and preventing secretory IgA from moving from intestinal epithelial cells into the mucus layers [6].
Mold exposure increases your vulnerability to fungal, viral, and parasitic infections [5].
Mold disrupts normal gut-immune functioning, leading to a persistent decline in microbial diversity, bacterial translocation, and a rise in recurrent bacterial infections [5].
These effects of mycotoxin exposure on your intestinal barrier and intestinal epithelial cells can cause significant inflammation and increased intestinal permeability, resulting in serious GI issues.
Because molds produce mycotoxins that weaken the gut’s defenses, exposure can make you more susceptible to infections. Many of my clients with mold-related illness have guts heavily colonized with pathogens due to the toxic environment mold creates inside the gut. This toxicity creates a welcoming home for gut pathogens. It’s common to find high levels of parasites, H. pylori, candida, and pathogenic bacteria in clients struggling with mold-related health problems.
Mold and GI Conditions
Mold exposure can increase the risk of serious gastrointestinal conditions. It has been linked to Irritable Bowel Syndrome (IBS), Small Intestinal Bacterial Overgrowth (SIBO), Inflammatory Bowel Disease (IBD), Crohn’s disease, Ulcerative Colitis, and chronic acid reflux.
Additionally, mold exposure can worsen the chronic inflammation associated with IBD. Mold-related toxins may trigger inflammatory processes that intensify IBD symptoms by increasing inflammation within the gastrointestinal tract.
If you are struggling with a chronic GI condition like those mentioned above, there is roughly a 50% chance that mold has contributed to the onset of your symptoms.
Mold and Immune-Related Conditions
Chronic mold exposure has been linked to a variety of immune-related and neurological symptoms and conditions, including Mast Cell Activation Syndrome (MCAS), histamine intolerance, autoimmune diseases, celiac disease or non-celiac gluten sensitivity, eosinophilic gastroenteritis, Chronic Inflammatory Response Syndrome (CIRS), a dysregulated immune system, and dysautonomia/POTS.
If you are experiencing any of these conditions, I strongly encourage you to explore mold as a possible contributing factor.
Gastrointestinal Symptoms of Mold Exposure
Mold exposure is linked to a variety of gastrointestinal symptoms because it affects the gut microbiome. Common digestive symptoms related to mold include:
Diarrhea
IBS & IBD
Abdominal pain
Bloating
Chronic constipation
Food sensitivities & intolerances
Histamine intolerance
Nausea
Vomiting
Leaky gut & increased intestinal permeability
The severity of these symptoms can vary depending on how sensitive you are to mold and how much exposure you’ve had. Mold isn’t the only possible cause of these symptoms, which is why it’s important to get proper lab testing. **You can learn more about the IBS labs I run inside my 1:1 practice here.
Chronic Inflammatory Response Syndrome (CIRS) and Gut Health
Long-term mold exposure can lead to a chronic condition called Chronic Inflammatory Response Syndrome (CIRS). This complex illness is linked to biotoxins (mycotoxins) from mold, which trigger an impaired immune response and severely weaken the immune system.
CIRS is more than just a mold allergy or sensitivity. It is a genetically influenced, chronic immune system dysregulation that continues even after mold exposure has stopped. From a functional medicine perspective, genetics and immune resilience play key roles. About 25% of the population carries HLA-DR genetic types that reduce their ability to clear biotoxins effectively. This results in a persistent, unchecked inflammatory response that often does not respond well to typical treatments.
Dr. Ritchie Shoemaker is the physician who first defined and researched CIRS extensively and created the CIRS symptom cluster map. Common symptoms of CIRS include:
Fatigue
Weakness
Difficulty assimilating knowledge
Aches
Headaches
Light sensitivity
Memory problems
Trouble finding words
Difficulty concentrating
Joint pain
Morning stiffness
Muscle cramps
Unusual skin sensitivity
Tingling sensations
Shortness of breath
Sinus congestion
Cough and respiratory symptoms
Excessive thirst
Confusion
Appetite swings
Difficulty regulating body temperature
Increased urination
Red eyes
Blurred vision
Night sweats
Mood swings
Sharp, ice-pick-like pain
Abdominal discomfort and pain
Diarrhea
Numbness
Tearing
Disorientation
Metallic taste
Static shocks
Vertigo
Histamine intolerance and allergic reactions
Because CIRS symptoms are widespread and can mimic other illnesses, it is often misdiagnosed. If you recognize several of these symptoms and have not found relief despite multiple treatments, there is a strong possibility you could have CIRS and biotoxin illness.
One of the biggest challenges with CIRS is that many mainstream doctors do not recognize it, which can leave patients feeling dismissed or misunderstood. The emotional and neurological symptoms may make patients feel like their condition is “all in their head”—when in fact, it is due to neuroinflammation.
Healing from Mold-Induced Chronic Illnesses
The first step to healing from mold is to remove yourself from the moldy environment. It doesn’t matter how healthy your diet is, how much magnesium or probiotics you take, you can’t heal in the same environment that made you sick. Trying to heal your body while living or working in mold is an uphill battle you will never win.
There’s no point in spending money on a bunch of detox protocols until you’re out of the mold–or until remediation is completed and successful.
The Best Lab Tests for Mold Exposure
If you suspect mold exposure is impacting your health—but your regular blood work keeps coming back “normal”—you’re not crazy, and you’re not out of options. Mold-related illness often flies under the radar in conventional medicine, but functional lab testing can help you detect if mold is to blame for your health issues.
Here are two of the most effective functional labs for identifying mold-related issues in the body:
1. Organic Acids Test (OAT)
The Organic Acids Test is a comprehensive urine test that evaluates over 70 markers and secondary metabolites produced by dysfunction related to gut health, detox pathways, energy production, and more. It’s especially helpful for detecting indirect signs of mold and fungal overgrowth by identifying metabolites produced by molds Aspergillus or Fusarium.
The OAT can detect elevated levels of fungal species metabolites, including oxalic acid and arabinose, which often point to mold colonization or candida overgrowth—common after mold exposure. It also shows if your mitochondria (energy factories) and detox pathways are under stress, which is often the case in people dealing with chronic mold exposure.
This test is non-invasive and is often a first-line tool I use with clients when mold is suspected but hasn’t been formally diagnosed.
2. Mycotoxin Panel
Mycotoxins are the toxic compounds produced by certain molds. Unlike mold spores, which your immune system may react to acutely, mycotoxins can accumulate in your tissues, damage your mitochondria & body systems, impair your detoxification pathways, and cause a wide range of chronic symptoms—from brain fog and fatigue to hormonal imbalances and histamine intolerance.
A mycotoxin panel is a urine-based test that screens for specific mycotoxins and tests for multiple mycotoxins including ochratoxin A, aflatoxins, and gliotoxin, among others.
This test tells you exactly what mold toxins are present in your body and in what quantities. It’s especially helpful for:
Confirming chronic mold illness & toxicity
Tracking your body burden over time
Personalizing your detox protocol based on which toxins you’re dealing with
Combined with an OAT, a mycotoxin panel gives a powerful snapshot of how mold is impacting your system and where your body needs the most support.
Comprehensive Detox and Mold Healing Protocol
Once elevated mold and mycotoxins are identified through functional lab testing (and after the client has removed themselves from the moldy environment), the next step is to follow a comprehensive detox protocol to combat the oxidative stress damage caused by reactive oxygen species.
It’s important to understand that, when dealing with mold-related illness, detox systems can be severely impaired. Therefore, many clients need to proceed slowly. Healing can take time—mild cases may require up to 6 months, while more severe cases often take a year or longer, depending on the individual.
Every client is unique, so detox and healing protocols are tailored to each person’s specific needs and lab results.
One key point is that mold exposure typically needs to be addressed first, regardless of other gut issues present, such as small intestine bacterial overgrowth (SIBO), H. pylori, candida, or parasites.
When supporting clients healing from mold, we generally focus on: improving drainage pathways, providing antioxidants and bioflavonoids, replenishing minerals, regulating the nervous system, optimizing diet and lifestyle, supporting antifungal treatments, restoring a healthy gut microbiota, and more—based on what each client requires.
Mold & Gut Health Summary
In summary, mold exposure can significantly impact gut health through the introduction of mycotoxins that disrupt the gut microbiota, compromise the intestinal barrier, and impair nutrient absorption. Many complex, chronic illnesses (like CIRS, POTS, autoimmune conditions, irritable bowel syndrome, & IBD) are linked to mold exposure.
The first step towards healing from mold-related illness is to remove yourself from the mold exposure. The second step is to test for the specific mold-induced imbalances contributing to your symptoms, and work with a practitioner who can help you rebuild your health and safely guide you through comprehensive detox protocol. If you want to learn more about how I support my clients through a root-cause approach to healing form mold, you can check out my Gut Well Program here.
I recently went through my own mold healing journey — If you want to learn more about how I healed myself from mold-illness with my signature root-cause approach, you can watch the full story here.
