Beyond allergies: mycotoxins and what mould really does in your body
by Kath P on May 28, 2026
Most conversations about indoor mould stop at allergies and asthma. That's where the strongest, most settled science sits, and it's where most people experience symptoms. But the research has been quietly moving past that for the better part of a decade now. To understand why mould-affected homes can produce such a wide range of vague symptoms in some people, we have to talk about mycotoxins.
What mycotoxins actually are
Mycotoxins are toxic compounds produced by certain moulds as part of their normal metabolism. They've been studied for decades in the context of food (think aflatoxins on grains and peanuts), where they're tightly regulated. The newer research focus is on what happens when these same compounds turn up in the indoor air and dust of water-damaged buildings.
A study published in the Journal of Occupational and Environmental Hygiene tested 100 samples of building materials from water-damaged buildings and found that moulds growing on a variety of indoor materials commonly produced mycotoxins. Importantly, mycotoxin-containing particles weren't confined to floor level — they settled on surfaces well above the ground, meaning normal breathing-height exposure is plausible.
How mycotoxins are thought to affect the body
Once inhaled (or absorbed through skin contact or ingestion of contaminated dust), mycotoxins can be absorbed efficiently by the body. Reviews summarising the toxicology describe several categories of effect documented in laboratory and animal research:
- Immunotoxic — disturbing normal immune function
- Neurotoxic — affecting the nervous system
- Pulmotoxic — directly damaging lung tissue
- Nephrotoxic and hepatotoxic — affecting kidneys and liver
- Developmentally toxic and, in some cases, carcinogenic
A 2023 mini-overview in the journal Current Opinion in Toxicology described how mycotoxin exposure can drive chronic inflammation — including the secretion of inflammatory cytokines — and noted that these inflammatory mechanisms are also implicated in some neuropsychiatric and non-respiratory symptoms reported by people exposed to indoor mould.
Where the evidence is strong, and where it isn't
Here's where it's important to be honest about the science.
Strong evidence: indoor moulds in water-damaged buildings often produce mycotoxins, those mycotoxins can be absorbed, and mycotoxins can cause measurable biological effects.
Less strong evidence: the dose at which indoor exposure causes specific named diseases in otherwise healthy adults. There's no internationally agreed safe exposure level for indoor mycotoxin inhalation, and current measurement methods aren't standardised enough to set one. The AWMF clinical guideline from a coalition of German medical societies confirmed sufficient evidence for an association between damp/mouldy buildings and respiratory disease, asthma, allergic rhinitis, hypersensitivity pneumonitis and respiratory infections — but stopped short of confirming a clear dose-response relationship for many of the other reported symptoms.
The honest summary: mycotoxins are real, they're produced by moulds we routinely find in damp homes, they can affect human biology, and the populations most likely to experience effects are immunocompromised people, genetically susceptible individuals, and those exposed at high levels for prolonged periods.
Who needs to take this seriously
If you have:
- A compromised immune system (chemotherapy, immunosuppressants, certain chronic illnesses)
- Known mould allergies or sensitisation
- Hypersensitivity pneumonitis or sarcoidosis
- Unexplained chronic symptoms in a home you suspect has dampness issues
...the case for taking mycotoxin exposure seriously moves from theoretical to practical. So does the case for not letting damp conditions develop in the first place.
The prevention principle
Even if you read all the research and conclude (reasonably) that the mycotoxin science is still maturing, the practical advice doesn't change. The conditions that allow mould to grow are the conditions that allow mycotoxin production. Control the moisture, control the mould, control the toxin load. There's no version of this where damp indoor conditions are neutral.
The simplest prevention is moisture control
Dew Moisture dehumidifiers stop mould before it has a chance to grow, let alone produce anything else. Browse our range and find the right size for your space.
About the author: Kath P is a writer and researcher covering indoor mould, humidity and environmental health at The Dew. Journal. Her work draws on WHO guidelines, peer-reviewed research and the real-world experiences of Australian homeowners and renters.
