Your health

When conditions conducive to fungal growth are present in the indoor environment, moulds can proliferate on various substrates and be found in the ambient air. The effects of moulds on the occupants’ health depend on the mode and extent of the exposure, the nature of the causal agent, and mainly the susceptibility of the exposed individuals (state of health, age, etc.).

Irritation and inflammation

Symptoms of eye, nose and throat irritation have often been associated with the presence of indoor fungal growth. It seems that all moulds, regardless of species, can cause irritation.


The allergic reactions caused by the inhalation of numerous species of moulds constitute a health problem recognized by clinicians. Allergic rhinitis and asthma are examples of allergic diseases associated with mould exposure.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis and other immune reactions are also possible with exposure to moulds. Exposure in an industrial or agricultural environment to large amounts of moulds can induce the production of antibodies and cause a syndrome calledhypersensitivity pneumonitis or extrinsic allergic alveolitis. Recent studies suggest that this disease could also develop in occupants of homes and apartments contaminated by moulds.


Few moulds among those growing on construction materials or in ventilation systems can cause infections. These infections occur for the most part in individuals with reduced immunity. While exposures to these pathogenic agents are not very common in residences, the infections resulting from exposures to these moulds can have very serious and even fatal consequences for immunosuppressed individuals.


The majority of the reported cases of human and animal mycotoxicoses are associated with the ingestion of contaminated foods. Few data exist on the inhalation of mycotoxins. However, we present all the toxicological data for information purposes. These data are all supported by experimental studies or clinical observations of human or animal pathologies.

It is important to remember that the extrapolation of toxicological data to other contexts must be done carefully. Data relating to the mycotoxins produced by a mould cultivated in the laboratory or growing in nature do not necessarily apply to the same mould growing in a home; nevertheless, some clinical and environmental data converge towards the possibility of cases of mycotoxicosis associated with significant exposures in premises contaminated by moulds. It is also important to bear in mind that the observations on mycotoxicoses in animals following the inhalation or ingestion of mycotoxins do not necessarily apply to humans.

The majority of the toxic effects caused by mould inhalation have been reported for exposures in an industrial or agricultural environment, meaning in locations where the concentration of mycotoxins is high and where the exposure is repetitive or chronic.


If you believe you are suffering from symptoms following exposure to moulds, you must first consult your physician or a health professional capable of properly evaluating your condition.

Only a physician can make the clinical diagnosis of a disease resulting from mould exposure.

The medical information contained in this site’s fact sheets must not replace a consultation with a physician.

Institut national de santé publique du Québec. Health Risks Associated with the indoor presence of mould 
University of Connecticut Health Center. Guidance for Clinicians on. Health Effects Related to Mold Exposure