Black Mold Symptoms: What the CDC and NIH Actually Say

"Black mold" usually refers to Stachybotrys chartarum, a greenish-black mold. But the EPA notes that "black mold" is not a species or specific kind of mold, and neither is "toxic mold". The CDC says Stachybotrys and other molds may cause health symptoms that are nonspecific, and that all molds should be treated the same with respect to potential health risks and removal.

So there's no special set of "black mold symptoms." What follows applies to mold in general. For what black mold looks like and how to remove it, see our black mold guide.

The CDC's starting point is reassuring: exposure to damp and moldy environments may cause a variety of health effects, or none at all.

Table: common mold symptoms in a house, and what each agency says about them.

The WHO reached a similar conclusion in its 2009 guidelines on damp and moldy buildings. It found that the most important effects are increased prevalences of respiratory symptoms, allergies and asthma, as well as perturbation of the immunological system.

Symptoms when mold is in the house: who is at higher risk

Not everyone reacts the same way. Based on the CDC and NIH:

• People with asthma or mold allergies. The CDC says they may have severe reactions.
• People with weakened immune systems or chronic lung disease. They may get infections in their lungs from mold.
• Young children. The NIEHS singles out children when it describes how mold exposure can increase a person's risk of developing asthma.

For these groups, the CDC also says people with asthma or who are immune compromised should not stay in a moldy home, or be there while it is being cleaned.

Dead mold can still cause symptoms

Spraying mold doesn't make it harmless. The EPA notes that dead mold is allergenic and may cause allergic reactions and other health effects in some individuals. That's why the goal is to remove mold, not just kill it.

The internet is full of claims that black mold causes a long list of serious illnesses. Here is what the major scientific reviews found.

In 2004, at the CDC's request, the Institute of Medicine (now part of the National Academies) reviewed the research on damp indoor spaces and health. A summary of its findings, published by the Massachusetts Department of Public Health and archived by the CDC, sorts health effects by strength of evidence:

Table: IOM 2004 evidence ratings, from the Massachusetts DPH summary of Table ES-1.

"Insufficient evidence" doesn't mean proven safe. It means the studies weren't strong enough to say either way. The CDC's current position on Stachybotrys fits this: at present, no test exists that proves an association between Stachybotrys chartarum and particular health symptoms, and a possible link to acute idiopathic pulmonary hemorrhage among infants has not been proven.

Research continues. The NIEHS mold page describes ongoing study of other possible effects of long-term exposure, including memory and mood. That's an open research area, not a settled diagnosis, which is one more reason to work with a doctor rather than self-diagnose.

Mold smell isn't proof of harm

Musty odors come from gases called microbial volatile organic compounds. The EPA says the health effects of inhaling mVOCs are largely unknown. A smell is a reason to find the moisture, as explained in our mold smell guide, not a sign that you're being poisoned.

Not one that's validated for diagnosing illness from a home. Some labs sell urine "mycotoxin" or "toxic mold" tests directly to consumers. A CDC report published in Morbidity and Mortality Weekly Report found:

• Low levels of mycotoxins are found in many foods; therefore, mycotoxins are found in the urine of healthy persons.
• Mycotoxin levels that predict disease have not been established.
• Urine mycotoxin tests are not approved by FDA for accuracy or for clinical use.
• The authors warned that patients and providers should recognize these tests might not be valid or clinically useful.

The same report says the CDC does not recommend biologic testing of people who work or live in water-damaged buildings, and that visual inspection and moisture assessment are the recommended first steps.

What a doctor can do is different. The CDC notes that the health effects of mold are different for different people. If you have symptoms, tell your doctor about the moisture or mold in your home, and let them decide whether any medical testing is warranted.

Why a home mold test doesn't diagnose you

A test of your air or walls measures mold in the building, not what's happening in your body. The CDC does not recommend mold testing of homes, and says sampling can't reliably show whether someone will get sick. The EPA adds that there are no federal limits for mold or mold spores, so results can't be compared against a health standard. Home testing is useful for other reasons, like finding hidden mold or confirming a cleanup. Our guides on how to test for mold and whether mold testing is worth it cover that.

See a doctor or other health professional if:

• Symptoms last or keep coming back. The CDC says people with persistent symptoms should see their physician.
• You have asthma and it's getting harder to control.
• You or a family member has a weakened immune system or chronic lung disease and lives with mold.
• You plan to clean mold yourself and have health concerns. The EPA says to consult a health professional before starting cleanup.
• A baby has breathing problems. The CDC says parents should make sure children get proper medical treatment.

If anyone has severe trouble breathing, get emergency care right away.

Tell your doctor about the mold and any water damage at home. That history helps them decide what, if anything, to test.

Your health and your house are two separate problems, and both deserve attention. For the house, the CDC's advice is direct: if you see or smell mold, you should remove it, and clean up the mold and fix the moisture problem.

In Texas, small jobs are allowed without a license. TDLR says areas of visible mold of less than 25 contiguous square feet can be cleaned up by people who are not licensed. If someone in the home is in a higher-risk group, or the mold is large or hidden, hire professionals:

• A licensed mold testing company (assessor) can find hidden mold and write a cleanup plan.
• A separate licensed mold removal company does the cleanup. Texas law bars one license holder from performing both mold assessment and mold remediation on the same project.

Look up licensed companies in Houston, Dallas, San Antonio or Austin, or browse the Texas directory. Use our license check tool to confirm any company's TDLR license, and see how we verify every listing.