6 min read

# Mycotoxins 101: The Invisible Toxins

You finally left the moldy apartment. The coughing eased. The headaches eased. Then, two weeks later, the fatigue and brain fog came back. It feels unfair and confusing.

If that is your story, you are not imagining it. It sounds like you did the right thing and still got knocked down. That is a real thing with mycotoxins, and it is why people can feel sick long after the visible mold is gone.

Mycotoxins are the chemical byproducts certain molds make to defend their territory. They are not spores. They are small, sticky toxins that can ride on dust, settle into fabrics, and linger in the body. This article will explain what they are, why they are so potent, and what you can do next.

## What are mycotoxins, in plain language

Mycotoxins are toxic secondary metabolites produced by specific molds. Think of them as chemical weapons. The mold does not need them to grow. It uses them to compete with other organisms and survive.

Not every mold makes mycotoxins, and not every strain makes them at the same level. That is why one home with visible mold can feel tolerable while another can flatten you. Species, strain, moisture, and age of growth all shape the toxin profile.

Here are the mycotoxins you will see most often in indoor environments and on urine panels.

If those names show up in your lab report, you are not alone. They are the usual suspects in water damaged buildings.

## Why mycotoxins feel worse than mold spores

Mold spores are particles. They can irritate airways, trigger allergies, and inflame tissues. Mycotoxins are chemical poisons that can enter cells and disrupt basic functions. That is why symptoms can feel systemic, not just respiratory.

This is why a small patch of mold can feel worse than a bigger area with low toxin production. It is not only the size. It is the chemistry.

## The science, without the overwhelm

You do not need a biochemistry degree to understand the basics. Here are four mechanisms that matter most.

### 1. DNA damage and cancer risk

Aflatoxin B1 is one of the best studied mycotoxins. It forms DNA adducts, which are pieces of toxin that bind directly to DNA and cause mutations. This is why aflatoxin B1 is classified as a Group 1 carcinogen by IARC. The mechanism is documented in classic DNA adduct research [doi:10.1038/25645](https://doi.org/10.1038/25645).

This does not mean you will get cancer from living in a moldy house. It means these chemicals are potent and deserve respect.

### 2. Immune suppression

Trichothecenes, including satratoxins and deoxynivalenol, inhibit protein synthesis. When cells cannot make proteins, they cannot mount a healthy immune response. That is why trichothecenes are linked to mucosal irritation and immune dysfunction [trichothecene immunotoxicity review](https://pubmed.ncbi.nlm.nih.gov/25172014/).

If you feel like you are always catching every bug, or your sinuses never calm down, this mechanism fits.

### 3. Kidney stress and detox load

Ochratoxin A is known for nephrotoxicity. The kidneys are a main route for toxin clearance, so repeated exposure can stress them. Reviews summarize this mechanism clearly [ochratoxin A toxicology](https://pubmed.ncbi.nlm.nih.gov/19756115/).

This is one reason some clinicians track kidney markers in complex mold cases.

### 4. Disrupted immune cell function

Gliotoxin, produced by Aspergillus fumigatus, can impair macrophages and neutrophils. These cells are your first line of defense against infection. Research shows gliotoxin has immunosuppressive effects [gliotoxin immune modulation](https://pubmed.ncbi.nlm.nih.gov/19321741/).

If your body feels less resilient than it used to, this is part of the why.

## How mycotoxins move through a home

Mycotoxins do not stay where the mold is. They bind to dust, float on tiny particles, and settle on porous materials. A leak in a wall can end up affecting the couch, your mattress, and the HVAC filter.

Common reservoirs include:

If you want to understand how to assess a space, see [testing your home for mold](/vault/testing-your-home-for-mold). If you are curious about ERMI scores, start with [ERMI testing explained](/vault/ermi-testing-explained).

## Why symptoms vary so much

It is common for one person in the home to be sick while another feels fine. That is not a contradiction. Genetics, detox capacity, prior health, and immune status all shape how you respond.

It sounds frustrating to be the one who is sick when everyone else looks okay. That is a real emotional hit. The variation is documented across toxicology and immunology research, and it is especially relevant in mold illness.

Common symptom clusters include:

– Brain fog, memory issues, and trouble focusing
– Sinus congestion, sore throat, or chronic cough
– Headaches, dizziness, or light sensitivity
– Fatigue that does not lift with rest
– Digestive issues, food sensitivities, nausea
– Skin rashes, itching, flushing
– Anxiety, irritability, sleep disruption

If you want a broader view of mold illness itself, read [what is mold illness](/vault/what-is-mold-illness).

## Testing, with realistic expectations

Testing can be helpful, but it is not perfect. There are two main buckets: environment and body.

### Environmental testing

– ERMI or HERTSMI dust tests for mold DNA and water damage markers
– Air sampling when a building is under investigation
– Surface sampling for targeted areas

These tests can tell you whether a building is likely to be a source. They can also help you see whether remediation reduced the burden.

### Body testing

– Urine mycotoxin panels
– Blood markers for inflammation and immune stress

Urine tests can confirm that your body is processing mycotoxins. A low result does not always mean no exposure. Some bodies store toxins rather than excrete them. Timing, hydration, and detox capacity all change the result.

## Practical steps you can take now

You do not need to do everything at once. Most people do best with a paced, methodical plan. Here is a simple sequence that lines up with what clinicians use in practice.

If you want a detailed binder breakdown, read [detox binders explained](/vault/detox-binders-explained). For remediation planning, start with [remediation what to expect](/vault/remediation-what-to-expect).

• Track where symptoms get worse and better
• Document leaks, musty odors, or visible growth
• Ask for an inspection if you rent
• Reduce dust with HEPA filtration and damp cleaning
• Work with a mold aware clinician if possible

## Why this gets missed so often

Mycotoxins are invisible. Standard air tests can miss them. Many doctors are trained to think about mold as allergy, not chemical toxicity. That gap leaves people stuck in a loop of normal labs and abnormal symptoms.

If you have been dismissed before, it makes sense that you feel guarded now. You are not too sensitive. You are picking up on something real.

## Read next

– [Mycotoxins explained in depth](/vault/mycotoxins-explained)
– [Understanding CIRS](/vault/understanding-cirs)
– [Hidden mold: where to look](/vault/hidden-mold-where-to-look)

## Sources

– [Aflatoxin B1 DNA adducts, DOI:10.1038/25645](https://doi.org/10.1038/25645)
– [Trichothecene immunotoxicity review, 2014](https://pubmed.ncbi.nlm.nih.gov/25172014/)
– [Ochratoxin A toxicology review, 2009](https://pubmed.ncbi.nlm.nih.gov/19756115/)
– [Gliotoxin immune modulation, 2009](https://pubmed.ncbi.nlm.nih.gov/19321741/)