Is Black Mold Dangerous? What Health Agencies Actually Say

Black mold has a frightening reputation, and search results do not help: you will find claims ranging from "harmless" to "deadly." The picture from health agencies is calmer and more useful. Indoor mold of any kind, including black mold, can cause health problems for some people, and some people are at much higher risk than others. The right response is the same in every case: remove the mold and fix the moisture.

This guide summarizes what the CDC and EPA say. It is general information, not medical advice. If you have symptoms or a health condition, talk to a doctor.

The short answer

• Black mold, the common name for Stachybotrys chartarum, can cause the same kinds of problems as other indoor molds: allergy-like symptoms, irritation, and asthma attacks in people with asthma.
• The CDC says the hazards of molds that may produce toxins should be considered the same as other common molds.
• Reports linking toxic mold in homes to rare, serious illnesses exist, but the CDC says they are few and a causal link has not been proven.
• People with asthma, allergies, chronic lung disease, or weakened immune systems are at greater risk.
• Whatever the species, the CDC and EPA advise removing indoor mold growth and fixing the moisture that caused it.

What mold can do to your health

According to the CDC, mold can cause a stuffy nose, sore throat, coughing or wheezing, burning eyes, or skin rash in some people. People with asthma or who are allergic to mold may have severe reactions, and people with weakened immune systems or chronic lung disease may develop lung infections from mold.

The EPA explains why: molds produce allergens, irritants, and in some cases potentially toxic substances called mycotoxins. Allergic reactions can be immediate or delayed, and mold exposure can irritate the eyes, skin, nose, throat, and lungs of people whether or not they are allergic.

The CDC also cites a 2004 review by the Institute of Medicine, which found sufficient evidence to link indoor mold exposure with upper respiratory symptoms, cough, and wheeze in otherwise healthy people; with asthma symptoms in people with asthma; and with hypersensitivity pneumonitis in people susceptible to that condition.

Many people living with some mold notice no effects at all. Reactions vary from person to person.

Why black mold is called "toxic"

Stachybotrys can produce mycotoxins, and in the 1990s it was linked in public reports to a cluster of serious lung bleeding in infants. Later review did not confirm that link. In its questions and answers on Stachybotrys, the CDC says there are very few case reports that toxic molds inside homes cause unique or rare conditions such as pulmonary hemorrhage or memory loss, that these reports are rare, and that a causal link has not been proven.

Being able to produce a toxin is not the same as producing it, and producing it is not the same as people being exposed to harmful amounts. That is why the CDC recommends treating the health hazards of these molds the same as other common molds, rather than as a special emergency.

Can black mold kill you?

There is no good evidence that black mold in a home kills otherwise healthy people. For most people, the realistic risks are allergy symptoms, irritation, and asthma flare-ups.

The serious exception is people with severely weakened immune systems. The CDC's clinical guidance after severe weather says people with immune suppression, such as people with HIV infection, cancer patients receiving chemotherapy, and people who have received an organ or stem cell transplant, should not enter buildings with indoor water leaks or mold growth. If that describes someone in your home, involve their doctor before any cleanup begins.

Who is most at risk

• People with asthma, especially those allergic to mold
• People with mold allergies or other respiratory allergies
• People with chronic lung disease
• People with weakened immune systems
• Children, who the CDC advises should not take part in disaster cleanup work

Is black mold worse than other mold?

Health agencies do not treat it as a separate category. The CDC says it is not necessary to determine what type of mold you have, because all molds should be treated the same with respect to potential health risks and removal. Color does not tell you the species, and the species does not change what you should do. See what black mold looks like and our black mold guide.

Is black mold in the walls dangerous?

Mold inside walls is out of sight but can still affect indoor air, and the bigger risk often comes when it is disturbed. The EPA warns that removing materials over hidden mold, such as wallpaper or drywall, can release large numbers of spores. Hidden growth is a job for a professional who can contain the area while opening it up. See signs of mold in your house.

If you think mold is affecting your health

• See a doctor. Tell them about the mold, any water damage, and when symptoms started. Your doctor decides what testing and treatment make sense.
• Do not try to diagnose yourself from symptoms. Coughing, congestion, headaches, and fatigue have many possible causes.
• Protect people at higher risk. Keep anyone with asthma, allergies, lung disease, or a weakened immune system away from the moldy area and from cleanup.

Reducing exposure while you deal with it

1. Stop the water source and dry the area.
2. Avoid disturbing large patches of mold.
3. Do not run the air conditioning if you suspect mold in the air handler or ducts.
4. Clean small areas on hard surfaces with detergent and water while wearing an N-95 respirator, gloves, and goggles, as the EPA advises.
5. Leave larger areas, mold on drywall or insulation, and hidden growth to a professional who uses containment. See DIY vs. professional mold removal.

When you are ready to remove it

If you own your home and the mold covers more than a small patch, sits inside walls, or is near someone at higher risk, a local remediation company can remove it under containment. You can call the number on this page to be connected with an independent mold remediation company, and our guide what is mold remediation explains what the work involves.