Health Effects That May Be Caused by Mold

Health Effects That May Be Caused by Inhaling Mold or Mold Spores

Inhalation exposure to mold indoors can cause health effects in some people. Molds produce:

  • Allergens (substances that can cause allergic reactions)
  • Irritants
  • Potentially toxic substances or chemicals (mycotoxins)

Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Mold does not have to be alive to cause an allergic reaction. Dead or alive, mold can cause allergic reactions in some people.

Allergic Reactions, Asthma Attacks, Irritant Effects

Allergic reactions to mold are common and can be immediate or delayed. Repeated or single exposure to mold, mold spores, or mold fragments may cause non-sensitive individuals to become sensitive to mold, and repeated exposure has the potential to increase sensitivity. Allergic responses include hay fever-like symptoms such as:

  • Headache
  • Sneezing
  • Runny nose
  • Red eyes
  • Skin rash (dermatitis)

Molds can cause asthma attacks in people with asthma who are allergic to mold. In addition, whether or not individuals are allergic to mold, molds can irritate:

  • Eyes
  • Skin
  • Nose
  • Throat
  • Lungs

Other Health Effects

Breathing in mold may also cause hypersensitivity pneumonitis, an uncommon disease that resembles bacterial pneumonia. In addition, mold exposure may result in opportunistic infections in persons whose immune systems are weakened or suppressed.

When mold grows indoors, the occupants of a building may begin to report odors and a variety of symptoms including:

  • Headaches
  • Difficulty breathing
  • Skin irritation
  • Allergic reactions
  • Aggravated asthma symptoms

These and other symptoms may be associated with exposure to mold. But all of these symptoms may be caused by other exposures or conditions unrelated to mold growth. Therefore, it is important not to assume that, whenever any of these symptoms occurs, mold is the cause.

For more detailed information on mold and its health effects, consult:

Damp Buildings

Although mold is frequently found in damp buildings, it is not the only potential contaminant — biological contaminants other than mold, and non-biological contaminants are often present and may also cause health effects. Damp buildings may attract rodents and other pests. Damp or wet building components and furnishings may release chemicals indoors.

Potential contaminants in damp or wet buildings include:

  • Bacteria
  • Dust mites
  • Cockroaches and other pests
  • Chemicals emitted by damp building materials and furnishings

For more information on damp buildings and health effects, see the 2004 Institute of Medicine Report, Damp Indoor Spaces and Health, published by The National Academies Press.