The Mold & Indoor Air Quality Library can't be printed. Read it online at a2zhomeco.com/mold-resources.
In the News Tarrant County jury awards $21.6M over sewer gas and mold October 14, 2026

Mold & Indoor Air Quality Library

Mold Basics & Health

How mold affects health

Best practice Sources: EPA 402-K-01-001, CDC Mold Cleanup Guide

In plain English

The most common effects are allergic: sneezing, runny nose, red eyes, rash. Mold can trigger asthma attacks in people who are sensitized to it, and it irritates the eyes, skin, nose, throat and lungs even in people who aren't allergic.

Dead mold is still allergenic. That's why the goal of a cleanup is to remove mold, not just kill it. People with weakened immune systems are more vulnerable to infection from some species, and CDC advises them to stay away from moldy sites.

If someone in the home has symptoms that worry you, talk to a doctor. An assessor can tell you where the mold is and how much there is, but not whether it is causing an illness.

Key points

  • Allergic reactions, asthma attacks and irritation are the common effects.
  • Hypersensitivity pneumonitis is uncommon but serious.
  • Immune-compromised people can develop infections (Aspergillus fumigatus, Trichoderma).
  • Spores can stay allergenic for years, alive or dead.

Official text

EPA 402-K-01-001 — Health Effects and Symptoms Associated with Mold Exposure pp. 39–41 Best practice

When moisture problems occur and mold growth results, building occupants may begin to report odors and a variety of health problems, such as headaches, breathing difficulties, skin irritation, allergic reactions, and aggravation of asthma symptoms; all of these symptoms could potentially be associated with mold exposure.

All molds have the potential to cause health effects. Molds produce allergens, irritants, and in some cases, toxins that may cause reactions in humans. The types and severity of symptoms depend, in part, on the types of mold present, the extent of an individual’s exposure, the ages of the individuals, and their existing sensitivities or allergies. Specific reactions to mold growth can include the following:

Allergic Reactions: Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic reactions to mold are common—these reactions can be immediate or delayed. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Mold spores and fragments can produce allergic reactions in sensitive individuals regardless of whether the mold is dead or alive. Repeated or single exposure to mold or mold spores may cause previously non-sensitive individuals to become sensitive. Repeated exposure has the potential to increase sensitivity.

Asthma: Molds can trigger asthma attacks in persons who are allergic (sensitized) to molds. The irritants produced by molds may also worsen asthma in non-allergic (non-sensitized) people.

Hypersensitivity Pneumonitis: Hypersensitivity pneumonitis may develop following either short-term (acute) or long-term (chronic) exposure to molds. The disease resembles bacterial pneumonia and is uncommon.

Irritant Effects: Mold exposure can cause irritation of the eyes, skin, nose, throat, and lungs, and sometimes can create a burning sensation in these areas.

Opportunistic Infections: People with weakened immune systems (i.e., immune-compromised or immune-suppressed individuals) may be more vulnerable to infections by molds (as well as more vulnerable than healthy persons to mold toxins). Aspergillus fumigatus, for example, has been known to infect the lungs of immune-compromised individuals. These individuals inhale the mold spores which then start growing in their lungs. Trichoderma has also been known to infect immune-compromised children.

Healthy individuals are usually not vulnerable to opportunistic infections from airborne mold exposure. However, molds can cause common skin diseases, such as athlete’s foot, as well as other infections such as yeast infections.

Sidebar: Potential Health Effects Associated with Inhalation Exposure to Molds and Mycotoxins

  • Allergic Reactions (e.g., rhinitis and dermatitis or skin rash)
  • Asthma
  • Hypersensitivity Pneumonitis
  • Other Immunologic Effects Research on mold and health effects is ongoing. This list is not intended to be all-inclusive.

The health effects listed above are well documented in humans. Evidence for other health effects in humans is less substantial and is primarily based on case reports or occupational studies.

Citation: EPA 402-K-01-001, Health Effects and Symptoms Associated with Mold Exposure, pp. 39–41.

Read on the official site ↗ See it in the full EPA 402-K-01-001

CDC Mold Cleanup Guide — Before you enter any moldy site Best practice
  • Protect yourself and loved ones against hazards. People with breathing problems like asthma or who have weakened immune systems should stay away from moldy sites. Children should not take part in disaster cleanup work. Check for loose power lines or gas leaks. Make sure the electricity and gas are turned off. Look for sagging ceilings or floors or other structural problems. Watch out for wet, muddy, or slippery floors.
  • Protect your mouth and nose against breathing in mold: wear at least an N-95 respirator. If you plan to spend a lot of time removing moldy belongings or doing work like ripping out moldy drywall, wear a half-face or full-face respirator.
  • Protect your skin. Wear protective gloves (non-latex, vinyl, nitrile, or rubber). Do not touch mold or moldy items with bare hands.
  • Protect your eyes. Wear goggles that provide complete eye protection. Choose goggles designed to keep out dust and small particles. Safety glasses or goggles that have open vent holes will not protect you against dust and small particles.

After you leave a mold site:

  • Shower and change your clothes. This will help you avoid carrying mold and other hazards back to your current living quarters.

Citation: CDC Mold Cleanup Guide, Before you enter any moldy site.

Read on the official site ↗ See it in the full CDC Mold Cleanup Guide

Citations