Signs of mold toxicity mirror symptoms of common health nuisances...but a nationally recognized mold remediator says exposure can lead to much greater health issues.
10 Warning Signs of Mold Toxicity, According to an Air Quality Expert
Updated on Jan. 09, 2025
Sneezing, coughing, or feeling down and tired? While these symptoms might make you think you’re coming down with a cold, you may want to keep an eye on how you feel over time. If these symptoms tend to linger or get worse whenever you’re at home, they could be warning signs of mold toxicity.
The Healthy by Reader’s Digest spoke with Michael Rubino, a mold and air quality authority, as well as the author of The Mold Medic: An Expert’s Guide on Mold Removal, and Amy Myers, MD, a physician and leader in functional medicine and gut health who’s personally struggled with mold toxicity.
Rubino points out that, in addition to respiratory issues, mold exposure has actually been linked to early-onset dementia and Alzheimer’s. “We spend 90% of our time indoors,” he says. “We’re learning new things every day about all the effects our homes can have on our health, but all signs are kind of leading into the same place that if we want to improve our health, the air we breathe has a very profound effect on it.”
10 Warning Signs of Mold Toxicity
“If you are regularly exposed to toxic mold, you may develop what’s called mold toxicity,” says Dr. Myers, who is also a two-time New York Times bestselling author. “This can be any illness brought on by exposure to toxic mold and mycotoxins.”
Mycotoxins are naturally occurring toxins produced by certain molds and fungi that can cause harm throughout the body. And while they’re responsible for many mold exposure symptoms, they can also have far-reaching implications on your health. “As mold exposure increases the toxic load on your system, the chances of developing an autoimmune disease begin to climb,” Dr. Myers explains.
While routine cleaning is extremely important for controlling the mold in your home, also be aware of these 10 warning signs of mold toxicity before any illness gets worse.
1. Trouble breathing
“Mycotoxins are often airborne and enter your respiratory tract,” Dr. Myers explains. “This triggers symptoms including asthma, allergies, and sinus infections.”
According to the U.S. Centers for Disease Control and Prevention (CDC), mold can cause irritation in the nose, throat, and lungs, even in people who don’t have asthma or aren’t allergic to mold—and this irritation can lead to trouble breathing.
The CDC also cites evidence that chronic mold exposure can worsen pre-existing asthma and that there’s an association between mold and new-onset asthma. In fact, past studies have estimated that mold in the home causes about 21% of new asthma cases in the United States.
2. Sneezing and coughing
While allergies are common, allergy-like symptoms—such as sneezing, coughing, itchy eyes and throat, and stuffy nose—are also early signs of mold exposure, or mold toxicity.
“Usually, it starts off with unusual allergies,” says Rubino. “They notice they’re getting sick more frequently; maybe their nose is stuffy [or] they’re having allergic-type symptoms,” explains Rubino.
He explains that these signs of mold toxicity can pop up with various timelines—sometimes immediately or sometimes with delayed reactions. If you’re experiencing chronic allergy-like symptoms while you’re at home, talk with your doctor.
3. You may feel fatigued
Let’s face it: Fatigue is a common symptom for lots of us. But Rubino points out that feeling fatigued is a common result of exposure to mold at home.
A 2013 study published in Toxins found exposure to different kinds of mold—especially mycotoxins, the kind of mold that can grow on food as well as under warm and humid conditions within the home—is linked to symptoms of chronic fatigue.
“Mycotoxins wreak havoc on your health by disrupting your mitochondria,” Dr. Myers explains. “Mitochondria produce energy for nearly every bodily function. That’s why mycotoxins can cause chronic fatigue or weakness.”
4. Brain fog
Along with fatigue, exposure to mold can cause brain fog, resulting in people feeling sluggish and even forgetful.
Rubino notes that it is typically a result of inflammation the body is experiencing when exposed to mold: “You start to experience gut issues due to the inflammation that mold and toxins can cause. Gut inflammation can lead to brain inflammation, which then can cause a whole host of neuropsychiatric symptoms.”
Per a 2023 review of research published in the Journal of Integrative Neuroscience, one study found that mold exposure can trigger a variety of cognitive impairments, including memory and learning problems, emotional functioning, and reaction time. Other studies cited that the neurological changes in people chronically exposed to mold are comparable to damage from chemical exposure or mild to moderate traumatic brain injury.
5. Anxiety and depression
“We are seeing a lot of studies that show that [mold is] impacting people’s mental health [through] people’s anxiety and depression,” Rubino says.
According to an article published in Environmental Health Perspectives in 2007, those who are exposed to damp, moldy households have a 34-44% higher risk of depression. Further studies, such as one published in Brain, Behavior, and Immunity in 2019, have demonstrated that mold exposure can increase anxiety-like behavior.
6. Headaches
Headaches are a common symptom of mold exposure, according to Dr. Myers. The mycotoxins that can trigger cognitive issues can also cause different types of headaches, ranging from dull pain to an “ice pick” sensation or even a migraine.
Other substances produced by some molds called microbial volatile organic compounds (mVOCs) may also cause headaches—even after short-term exposure, according to 2024 research published in Hygiene and Environmental Health Advances.
7. Light sensitivity
Dr. Myers says that chronic mold exposure can cause vision problems such as light sensitivity. According to the Journal of Integrative Neuroscience research, this is because mycotoxin inflammation can affect your optic nerve (a condition called optic neuritis)—and optic nerve inflammation can lead to blurred vision, reduced visual fields, and sensitivity to light.
Fortunately, these vision issues can be reversed with treatment.
8. Eye irritation
Exposure to mold and its mycotoxins can cause inflammation on the ocular surface as well, according to research published in the journal Toxins in 2017. Even at low levels, this mold-induced inflammation can cause eye irritation and sensitivity, prompting symptoms like dry, itchy, and red eyes.
9. Frequent illness
Exposure to mycotoxins may also show up as cold or flu-like symptoms, Dr. Myers says. And because of the way these toxins affect your body, it can feel like you’re catching one cold after another.
“Compromised mitochondria release free radicals,” Dr. Myers explains. “These unstable atoms create oxidative stress, causing cellular damage and inflammation.”
Your body’s immune system function is strongly regulated by oxidative stress and inflammation, per 2020 research published in Nutrients. So, as chronic exposure to toxic mold triggers more and more oxidative stress, it becomes harder for your immune system to respond to infections.
10. Skin irritation
If you have a mold allergy, it’s common to get a skin rash from inhaling or touching mold, according to the CDC. But mold exposure can irritate your skin even if you’re not allergic.
This is because “mycotoxins may also pass through your intestinal wall,” Dr. Myers says. “Once they get into your bloodstream, they can cross tissue barriers,” affecting your brain and other organs, such as your skin.
Other warning signs of mold toxicity
Mold’s effect on the body can be different from one person to the next. Beyond the 10 warning signs of mold toxicity noted above, Dr. Myers says that other common mold toxicity symptoms can include:
- Unexplained weight gain or weight loss
- Mood changes
- Numbness and tingling in the body
- Vertigo or dizziness
- Pain (abdominal pain or muscle pain similar to fibromyalgia)
- Tinnitus (ringing in the ears)
- Digestive issues (bloating, food intolerances)
- Metallic taste in the mouth
- Excessive thirst and dehydration, bed-wetting in children
- Symptoms similar to hormone imbalances (hair loss, rashes)
How to know if there’s mold in your home
According to the U.S. Environmental Protection Agency (EPA), mold thrives in moist, damp, and poorly ventilated areas of the home. For instance, mold can start growing if you’ve had recent water damage from a roof leak or burst pipe—and the longer the mold grows, the more damage it causes.
But day-to-day, several areas of the home are particularly susceptible to mold growth due to low air circulation, high humidity, or regular moisture. These hotspots can include:
- Bathrooms and sinks
- HVAC (heating/ventilation/air conditioning) systems
- Air ducts
- Behind the fridge
- Basements
How to test for mold
To check for toxic mold in your home, Dr. Myers recommends two tests. “The EPA developed a research tool—the Environmental Relative Moldiness Index (ERMI)—to test for mold and mycotoxins,” she says. “Dust samples are collected in a home, and DNA from mold in the dust is analyzed.” The sample is then compared to the ERMI index.
“You can hire a company to do this or use one of the many kits,” she says. “Some of these include professional evaluation of the results, and some you compare to a chart.”
Another testing option is to have a certified mold testing company run a spore capture test, a type of air quality test. “This mold toxicity test will see if you have high mold concentration levels in your home,” Dr. Myers explains. “The problem with this test is it doesn’t test specifically for mycotoxins. You may have a high mold concentration, yet it doesn’t necessarily mean these are toxic molds.”
For instance, she says mold caused by water damage should be fixed ASAP. “However, these molds are not necessarily creating mycotoxins.” That’s why if you’re unsure, it’s good to work with a professional who specializes in testing for toxic molds.
How to prevent mold from growing in your home
Controlling moisture in your home is the key to preventing mold growth, according to the EPA. The best way to do this is to keep indoor humidity levels below 60%—and ideally between 30-50%.
To do this, the agency advises that you:
- Fix leaks within 48 hours.
- Vent appliances that use moisture to the outside when possible, including dryers, stoves, and gas heaters.
- Run the bathroom fan or open a window when showering.
- Use exhaust fans or open a window when cooking or washing dishes.
- Use dehumidifiers where needed, such as in a basement.
- Note that if you see condensation collecting on windows, walls, or pipes, as this can be a sign of high humidity in the home.
The EPA also suggests covering cold surfaces like pipes with insulation (as this can limit condensation) and to keep air circulation flowing through your home.
When to see a doctor
“Anyone can be negatively affected by molds, from infants to the elderly,” Dr. Myers says. “Everyone also processes mold exposure differently.”
But she says that certain factors can further influence the severity of mold and mycotoxin exposures, such as:
- Home conditions: If you live in very humid areas or have water damage in your home, you’re more likely to encounter mold.
- Inflammation: “Chronic inflammation in the body makes you more susceptible to toxic mold,” Dr. Myers says. “This is because the immune system is overworked and worn out.”
- Foods: “Commercialized [processed] foods can develop mold during processing or storage,” she says.
“If you are experiencing any symptoms and identify with the above factors, I recommend seeing a functional medicine doctor for testing,” advises Dr. Myers.
She also says that some people are genetically predisposed to mold sensitivities. “For instance, I have the HLA-DR gene that prevents me from clearing both toxic mold and mycotoxins,” she says. “Consider having genetic testing done to see if you’re at risk.”
To check if you currently have mycotoxins in your body, Dr. Myers says several diagnostic tests are available. “I like to start with a urine test from RealTime Labs. They test for several specific types of mycotoxins that may be in your body.”
What to do if you have mold toxicity
If you do have mycotoxins in your body, the first step is to remove yourself from certain environments. “Determining the source of the mold problems can be difficult,” Dr. Myers says. “This way, you can establish which [environments] trigger mycotoxin symptoms.”
Still, whether your encounter was brief or chronic, you can recover from the harmful effects of mold and mycotoxins. Dr. Myers recommends a few strategies for combating mold symptoms:
- Clean your home of toxic mold.
- Eliminate inflammatory foods such as sugar, alcohol, caffeine, and artificial sweeteners.
- Manage your stress levels.
- Prioritize good nutrition, and eat foods rich in antioxidants and amino acids.
- For her patients, Dr. Myers also recommends supplements such as glutathione, which promotes immune system function and tissue repair, and L-Tyrosine, which supports your central nervous system.
About the experts
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Sources
- U.S. Centers for Disease Control and Prevention: “Mold”
- Integrative Medicine: A Clinician's Journal: “Is Mold Toxicity Really a Problem for Our Patients? Part I—Respiratory Conditions”
- Toxins: “Detection of Mycotoxins in Patients with Chronic Fatigue Syndrome”
- World Health Organization: “Mycotoxins”
- Journal of Integrative Neuroscience: “Mold and Mycotoxin Exposure and Brain Disorders”
- Environmental Health Perspectives: “Mental Health: Molding a Link to Depression”
- Brain, Behavior, and Immunity: “Mold inhalation causes innate immune activation, neural, cognitive and emotional dysfunction”
- Hygiene and Environmental Health Advances: “Volatile organic compounds (VOCs) in residential indoor air during interior finish period: Sources, variations, and health risks”
- Toxins: “Impact of Mycotoxins Secreted by Aspergillus Molds on the Inflammatory Response of Human Corneal Epithelial Cells”
- Nutrients: “Strengthening the Immune System and Reducing Inflammation and Oxidative Stress through Diet and Nutrition: Considerations during the COVID-19 Crisis”
- U.S. Environmental Protection Agency (EPA): “A Brief Guide to Mold, Moisture and Your Home”
