Indoor mold can cause respiratory problems. While mold exposure is also often cited as a cause of fatigue, there is no scientific evidence to support or disprove this.

Molds do cause respiratory allergy and infections. Allergic diseases include rhinitis, asthma, bronchitis, bronchiectasis, allergic pneumonia, alveolitis and diffuse pulmonary fibrosis.

Some molds are also capable of infecting the respiratory system. However, infection generally occurs in immunocompromised individuals. The most common cause of lung infection is Aspergillus fumigatus. Aspergillus fumigatus is a concern in hospital environment since it can easily infect patients.