What exactly is black mold?

North Carolina Mold Services

What exactly is black mold?

Medically reviewed by Jill Seladi-Schulman, PhD on June 1, 2018 — Written by Tim Jewell

“Black mold” refers to several species of mold (which is a type of fungus) that have a dark green or black appearance. The most common species is Stachybotrys chartarum.

These molds thrive in warm, frequently moist environments, including baths, showers, toilets, kitchens, and basements. They can also grow on wood, dirt, or paper. Mold may grow even more plentifully in humid climates or if you use a humidifier indoors.

Many black molds are toxigenic, meaning that they release toxins that can be irritating or even harmful for people who have preexisting conditions. Called mycotoxins, they’re produced as mold spores eat, grow, and form colonies with other spores.

High concentrations of mycotoxins may cause mold poisoning even in healthy individuals depending on the concentration of mycotoxins, the amount of time exposed to them, and other variables.

Learn how to identify mold poisoning symptoms, how mold poisoning is diagnosed and treated, and how you can cope with and reduce toxic molds in your home.

What are the symptoms of mold poisoning?

Mycotoxicosis, or “mold poisoning,” can affect the upper respiratory system with symptoms like those of a cold or flu. Additional symptoms brought on by mycotoxins are especially harmful or even fatal to someone with allergies or asthma.

Common mold poisoning symptoms for those without a respiratory condition include:

  • coughing
  • wheezing
  • nose stuffiness
  • itchy or red eyes
  • itchy skin

If you have allergies or asthma, you may experience more severe forms of these symptoms or have other serious symptoms, such as:

  • headaches
  • feeling exhausted
  • frequent coughing, especially at night
  • sinusitis
  • allergic reactions
  • chest colds
  • fever
  • difficulty breathing

Long-term mold exposure, even if it doesn’t cause immediate symptoms, may also lead to:

  • losing your hair
  • anxiety
  • confusion or memory loss
  • numbness in hands and feet
  • stomach pains
  • sensitivity to light
  • gaining weight for no reason
  • muscle cramps

Mold exposure can cause severe symptoms if you have any of the following conditions:

Mold exposure can be harmful to anyone but especially so to young children. A 2012 study of 36 species of molds in 289 homes with 8-month-old infants found that infants and young children exposed to mold may be more likely to develop asthma later in life.

How is mold poisoning diagnosed?

Mold poisoning can’t always be diagnosed by symptoms alone. Blood tests, allergy tests, and assessments of mold levels in your home may all be needed to specifically diagnose mold-related illness.

To test for mold poisoning or allergies, your doctor may perform one of these tests:

Blood test. Your doctor takes a blood sample and sends it to a testing laboratory to test for the reaction of certain antibodies in your immune system to different mold species, including black mold. This can help diagnose both mold allergies and more severe reactions to mold that may indicate mold poisoning. A blood test can also check for biotoxins in your blood from mold exposure, which can also reveal mold poisoning.

  • Skin prick test. Your doctor takes tiny amounts of mold and applies it to your skin using a tiny needle. Your skin will break out in bumps, a rash, or hives if you’re allergic to that mold species.
  • How is mold exposure treated?

Treatment for mold allergies and exposure symptoms may include:

  • Nasal sprays or rinses. Over-the-counter nasal corticosteroids, such as fluticasone (Flonase), reduce airway inflammation caused by mold allergies. Also, a solution of warm, distilled water and saline can help rinse your nasal passages of mold spores and remove congestion.
  • Over-the-counter (OTC) medications. Antihistamines, such as cetirizine (Zyrtec) or loratadine (Claritin), reduce your immune system response, minimizing airway inflammation. Decongestants, such as pseudoephedrine (Sudafed), help keep down swelling due to allergic reactions.
  • Montelukast (Singulair). This oral medication reduces mucus in your airways, which reduces symptoms of both mold allergies and asthma.
  • Allergy shots. Your doctor may recommend getting regular shots with small amounts of allergens to build up your body’s immunity to them over time.

Identifying mold in your home

  1. Look for black, clustered growths, especially in warm, moist rooms. Pay attention to whether you start coughing, sneezing, or wheezing when you enter the room — even if you don’t see mold, the spores or mycotoxins can still cause symptoms.
  2. Look for causes of mold growth, such as a leak, lack of ventilation, or old food, papers, or wood.
  3. Resolve any issues causing mold growth. Throw away anything affected by mold or contributing to mold growth.
  4. How do I manage mold?


Clean and vacuum your home regularly.

  • Leave doors and windows open for ventilation when you bathe, shower, or do other activities that can increase moisture.
  • Use a dehumidifier to keep indoor relative humidity (RH) below 50 percent.
  • Use an indoor air purifier with high-efficiency particulate air (HEPA) filtration or install an appropriate high-efficiency filter in your furnace or ventilation system.
  • Make sure your rain gutters are clean and not blocking water drainage.


  • Don’t leave old books, newspapers, or wood sitting unused for long periods.
  • Don’t put carpet in rooms like bathrooms, kitchens, and basements.
  • Don’t ignore leaks from pipes or groundwater—fix them as soon as possible.

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