Generally, mold exposure causes respiratory health symptoms, such as coughing, sneezing, difficulty breathing, asthma, etc. These should be the first signs that one can experience when exposed to mold. However, many viruses and even pollens may cause very similar respiratory health symptoms. There are some notable signs that can be recognized when it comes to mold problems, the first often being an odor. A musty, foul, stuffy, off-putting and persistent smell can be an indicator of a hidden mold problem. Another noticeable sign is water infiltration or water damage, from a known ongoing or past leak, flood or condensation issue. Another way to identify a potential mold issue is to find the actively growing mold colonies, which can look like dark spots on surfaces or brightly colored stains. However, not all mold problems are visibly apparent or obvious, as they can be hidden under flooring, behind walls, or even within furniture.
Within our unique and complex human bodies, mold spores or fungal particles are recognized as foreign intruders. As such, your immune system will send white blood cells, macrophages, which will engulf and destroy these fungal spores, utilizing internal digestive enzyme, lysing the fungal cells and killing them.
In addition to respiratory health symptoms, long term exposure can facilitate new problems to develop, such as pathogenic infections. These are most common in people with a compromised immune system, or those already living with lung related issues. Pathogenic infections happen when mold spores germinate within the body, utilizing the body as a substrate for growth. These types of infections can become dramatic very quickly as they can turn to generalized pathogenic infections, where the bloodstream can be used as a highway for fungal particles to reach the entire body. Finally, if caught early enough, most of these pathogenic fungal infections can be treated with the use of anti-fungal medication.
⬡ Microscopic photo of Stachybotrys spores taken by Brian Petit; Microbiology Department at Axxonlab (2025)
Mold can have a wide range of effects on people. These effects range from allergic reactions and rashes from direct skin contact with mold spores or colonies. Onychomycosis (fungal nail infection), for example, is primarily caused by dermatophytes or yeasts, with non-dermatophyte molds being rare causes.
Long-term exposure to mold may be associated with symptoms like brain fog, dizziness, headaches, and nausea in some reports, though evidence linking these directly to mycotoxin neurotoxicity in humans from environmental exposure is limited and primarily based on animal studies or anecdotal evidence.
The second potential mechanism is Sick Building Syndrome (SBS), where symptoms occur primarily in a specific building and may involve multifactorial causes including poor ventilation, chemical contaminants, biological factors like mold, and psychological elements such as stress; it is not solely a psychological nocebo effect.
Mold spore inhalation can cause coughing, sneezing, shortness of breath, an increase in asthmatic symptoms, etc. Most mold spores are common allergens and can cause allergic reactions such as itchy eyes, runny nose, and congestion, especially in susceptible individuals.
Mycotoxin panel tests are probably the most common way to test for mold exposure within the body. These tests normally involve a urine or blood sample, which is tested using methods such as mycotoxin specific ELISA-type assays or using mass spectrometry-detected analytical tests to obtain quantitative results regarding mycotoxin concentrations in the body. These types of tests are often expensive and are incapable of determining the source of the mold contamination; however, mycotoxin testing in urine or blood is controversial and not reliably validated for diagnosing mold-related illness from environmental exposure, as it may detect unrelated dietary sources and lacks clinical utility according to some experts.
Since these types of tests commonly test blood or urine samples, they are best for detecting mycotoxins that have already entered the body through consumption of moldy food. Inhalation of mold spores, except in excessive amounts, will very rarely be capable of being detected in these types of mycotoxin panels. Mycotoxins are not always produced by mold; even the notorious black mold species—Stachybotrys chartarum – do not always produce mycotoxins. Thus, mycotoxins alone are rarely a good indicator for identifying a mold problem. When it comes to mold spores within your air at home, the best way to test is with an air quality mold assessment, where the fungal spores within your air are collected using spore traps and analyzed under the microscope to quantify and identify them.
If consumed, mold normally exhibits symptoms such as nausea, vomiting, and diarrhea. Depending on the type of mold consumed, and if it produces mycotoxins, the range of symptoms can vary greatly. Take, for example, Fusarium, a white-pink mold commonly found affecting grains in storage. This mold species is known for producing a large variety of mycotoxins, most notably T-2 toxin, a trichothecene. T-2 toxin causes toxic alimentary aleukia, which has a host of horrible symptoms that can lead to death if untreated.
This mycotoxin is so potent it was alleged to have been used as a chemical weapon in ‘yellow rain’ incidents, though this remains controversial and some evidence suggests natural origins like bee pollen.
TL;DR ➡ Don’t eat moldy food.
Exposure to mold can have significant adverse effects on health, including allergic reactions and potentially serious infections, particularly in cases of prolonged inhalation. Recognizing early indicators, such as musty odors, signs of water damage, or visible growth, is essential for timely intervention. Reliance on expensive and unvalidated tests is not recommended; a professional mold assessment that includes air and surface testing is the most effective method to confirm a contaminate issue. If you are in doubt, or want to connect with a mold professional about your concerns, we encourage you to book a free virtual mold assessment. Let the mold experts at Axxonlab guide you, at no cost, anywhere in the world!
Mycotoxins are secondary metabolites, produced by actively growing fungi, under specific environmental conditions. These mycotoxins are normally contained within the fungal cells, and thus may remain in the environment, even after the fungus dies. Fungal cells commonly have chitin within their cell walls, making them quite resilient to physical damage from various sources, allowing mycotoxins to remain in the environment long after a mold problem may be thought to be over. Mold spores may contain mycotoxins depending on the species and environmental conditions, but not all spores do; mycotoxins are secondary metabolites produced under specific circumstances. Normally, mycotoxins are produced by specific fungal species, most notoriously Stachybotrys, but even Aspergillus and Penicillium species which are often regarded as common molds, may produce mycotoxins. The substrate, or surface upon which mold is growing, is also an important factor to mycotoxin production. For instance, materials with low available organic matter to consume, like mineral wool, tend to have low concentrations of mycotoxins, when moldy. While nutrient rich materials, like cellulose containing materials such as wood or drywall paper, commonly have higher mycotoxin concentrations when moldy. Another variable to mycotoxin production is the amount of available water. Studies have shown that mycotoxin production is at its highest when the available water for the fungus surpasses 95% aw.
Mycotoxins are generally small compounds that are not volatile, and that have toxic effects on the human body. These toxic effects can be quite varied. For example, trichothecenes primarily inhibit protein synthesis and can be cytotoxic; some may exhibit genotoxic effects, but their link to causing mutations and cancer in humans is not as established as for other mycotoxins like aflatoxins. Other mycotoxins imitate hormones within the human body, causing various issues. For example, Zearalenone is an estrogen analog, known as a mycoestrogen, and causes many developmental, and gestational issues in females.
