Mold-related illness is becoming increasingly common — but why does it happen?
There are two main ways mold affects our health:
1. Allergy-like symptoms
2. More severe neurological, digestive, or skin-related issues
Here are some of the most common symptoms we hear about:
Allergy-like symptoms
The most common reaction we see comes from high mold exposure overwhelming the immune system. Your body treats mold spores like a constant threat, triggering inflammation as a defense. That’s why you might feel like you have a cold that never ends — with symptoms like congestion, sore throat, itchy eyes, or even low-grade fever.
Unlike a virus, though, mold exposure doesn’t just pass on its own, so your body stays in a heightened immune state, which can wear you down over time.
More severe symptoms
In more extreme cases, health issues are linked to toxins that some molds produce, called mycotoxins. These can trigger a wide range of chronic symptoms — from brain fog and gut problems to skin rashes or even early signs of cognitive decline. While it’s not always the mold itself causing the damage, removing mold often eliminates the root of the issue.
If you're curious, you can read below how different spore types and the mycotoxins they produce could impact your health. We've also compiled some great podcasts and articles on mold here if you want to learn more.
“Not all mold is toxic. Some is allergenic and some are pathogenic, some non-toxic”
- Bridgit Danner, LAC, FDNP
These are the most common mold strains that show up on our tests. Please call us or check out how to read a mold report determine the acceptable "mold load" in your home:
Aspergillus
Common indoor and outdoor mold. Can cause allergy like symptoms in high spore concentrations. Can also produce mycotoxins like aflatoxins.
Penicillium
Known for antibiotic production (penicillin) but is also very common in homes and in high concentrations it causes allergic reactions.
Stachybotrys
One of the marker molds, also known as 'black mold'.
Produces mycotoxins and can cause severe respiratory and neurological symptoms. The color is acutally more green than black.
This mold is unhealthy at almost any level.
Basidiospores
Very common mold after there has been water damage or wood rot in a home. Similar to Aspergillus, its fine at low levels but at high levels you will wake up with stuffed sinuses every day.
Chaetomium
This is a toxic "marker mold" most often found after a serious water event. Can produce mycotoxins causing respiratory issues and skin infections.
This mold is unhealthy at almost any level.
Cladosporium
Common mold that will grow wherever it finds constant moisture. Similar to Aspergillus, it only becomes harmful at high spore concentrations or if someone is sensitive to mold.
Trichothecium
Produces trichothecene mycotoxins, which can lead to respiratory and immune system issues.
Bipolaris
This is a mold that typically hurts plants but if it gets in your house it can cause sinus and asthma-like symptoms. It will show up occasionally on our tests.
Petromyces
Found in agricultural settings. Produces mycotoxins that may contribute to food spoilage.
Neopetromyces
Closely related to Petromyces. Produces mycotoxins and is still under study for potential health risks.
Rhizopus
Common in bread mold. Can cause mucormycosis, a serious infection affecting sinuses and lungs.
Mucor
Grows in soil and moist environments. Can cause respiratory infections, especially in immunocompromised people.
Streptomyces
A bacterium that behaves similarly to mold. Produces antibiotics but can cause skin infections like actinomycetoma.
Everyone has different reactions but the worst on this list are the “marker molds” Stachybotrys (aka black mold) and Chaetomium which most commonly come from past sewage backup or pets urinating or defecating inside. It is mold from human or animal waste and if your mold test comes back with even one spore, you should take immediate action to treat your home.
The most common in this list are Aspergillus and Penicillium and at certain levels they can be hazardous to your health as well.
A high load of mold spores alone can make you sick but oftentimes it is the mycotoxins from mold that is truly toxic. Mycotoxins are the buy products of the lifecycle of mold (think of it like a mold burp). Here are the most common Mycotoxins that may be making you sick.
Mycotoxin
Produced by
Health Effects
Aflatoxin M1, B1, G1
Aspergillus species
Carcinogenic, primarily affecting the liver; found in contaminated crops.
Ochratoxin A
Aspergillus and Penicillium species
Nephrotoxic, linked to kidney disease, immune suppression, and potential carcinogenic effects.
Sterigmatocystin
Aspergillus species
Carcinogenic, leading to liver damage; found in stored grains and certain cheeses.
Zearalenone
Fusarium species
Estrogenic effects, causing reproductive issues; found in grains.
Roridin E
Stachybotrys and Fusarium species
Highly toxic, causing respiratory and neurological damage.
Verrucarin A
Stachybotrys species
Causes immune suppression, respiratory issues, and skin irritation.
Enniatin B
Fusarium species
Can cause digestive and immune system issues; found in grains.
Fumonisins
Fusarium species
Neural tube defects in humans, brain disease in horses; found in contaminated corn.
Chaetoglobosin A
Chaetomium species
Cytotoxic, causing respiratory issues and skin irritation.
Citrinin
Penicillium and Monascus species
Nephrotoxic, affecting kidney function; found in rice and cheese.
Mycophenolic Acid
Penicillium species
Immunosuppressant, toxic if ingested in contaminated food.
Gliotoxin
Aspergillus species
Immunosuppressive, toxic to lungs and causes oxidative stress.
Patulin
Penicillium and Aspergillus species
Carcinogenic, causes gastrointestinal distress; found in apples.
Nivalenol
Fusarium species
Immune suppression, gastrointestinal distress, reproductive issues.
Dihydrocitrinone
Penicillium species
Nephrotoxic, affects kidney function similarly to citrinin.
Satratoxin G
Stachybotrys species
Potent toxin causing respiratory, skin, and neurological symptoms.
T-2 toxin
Fusarium species
Skin lesions, immune suppression, gastrointestinal distress, and neurological issues.
Diacetoxyscirpenol
Fusarium species
Skin irritation, respiratory issues, immune suppression.
Isosatratoxin
Stachybotrys species
Severe respiratory, skin, and neurological symptoms.
Trichothecenes
Fusarium, Stachybotrys, and other species
Inhibits protein synthesis, leading to immune suppression, skin, and respiratory issues.
