Black mold does not affect everyone in the same way, but those with an allergy or sensitivity to the spores may experience symptoms such as congestion, red eyes, respiratory problems, skin rashes and so on. In some cases, an infection may occur.

Mold is a type of fungus. It is present almost everywhere, including in the air. In general, normal amounts of mold in the environment do not pose a substantial health risk to healthy people with regular immune system function.

There is no single type of mold called “black mold” — many molds are black. When people use the term, they may be referring to a type called Stachybotrys chartarum (S. chartarum), also known as Stachybotrys atra.

The Centers for Disease Control and Prevention (CDC) state that a person does not need to identify which type of mold is growing in their home or another building.

However, some people may be more sensitive to mold spores than others, and they may develop respiratory symptoms after inhaling even a small number of spores. In large quantities, mold spores can cause ill health in almost anyone.

Therefore, people should remove any mold growth in the home and take steps to prevent it from growing back.

This article explores some facts and myths surrounding black mold exposure. It also describes ways to remove and prevent mold growth in the home.

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There is a commonly held belief that black mold — sometimes called toxic mold — can cause severe health problems because it releases mycotoxins. Mycotoxins are toxic substances that some fungi produce.

Some research suggests that mycotoxins from S. chartarum have a link to serious health problems in people who live in contaminated buildings.

One such health concern is mycotoxicosis — mold poisoning. Others include:

However, people rarely report these symptoms, and it is not clear if they have links to mold exposure. Furthermore, research into the risks of inhaling mold spores is still ongoing, and further conclusive research about these rare symptoms is necessary.

Mold exposure can cause other symptoms, however. According to the National Institute of Environmental Health Sciences, it can cause the following types of health problems:

Allergy and irritation

People with allergies may be more sensitive to mold than others. If they come into contact with mold, they can experience symptoms such as:

In rare cases, mold allergies may cause more severe reactions, including hypersensitivity pneumonitis. Symptoms of chronic hypersensitivity pneumonitis include:

Mold exposure may also worsen asthma or lung problems in people with preexisting lung conditions.

An older study found that infants and young children with exposure to mold in the home had an increased risk of developing asthma by the age of 7. The research examined 289 homes and 36 types of mold.

However, S. chartarum was not among the three types of mold most strongly associated with asthma development.

Older research indicates that spending time in damp indoor spaces is related to respiratory symptoms, including those of asthma.

According to the CDC, more recent studies have supported these findings, particularly in relation to the link between mold exposure and asthma in young children.


For people with healthy immune systems, mold infections (a type of fungal infection) are not a problem.

However, people with weakened immune systems — such as those with HIV, transplant patients, or people undergoing cancer treatment — are at risk of fungal infections.

Toxic effects

Some people believe that black mold is particularly dangerous because it releases mycotoxins. However, many molds are capable of producing mycotoxins. Just because mold is present does not mean that it is producing these toxins.

It is also important to note that even molds that do produce mycotoxins may not produce them in all environmental conditions. Furthermore, a person may not inhale mycotoxins upon exposure to a mold that produces them.

A person can contract mold poisoning from eating moldy food, rather than from inhaling fungal spores in the home or outdoors. There is no conclusive evidence to indicate that inhaling or touching mold can cause mycotoxicosis.

An older report was unable to support claims that issues such as fatigue, lung disease, or cancer result from mold exposure.

The CDC state that there are very few reports of unique or rare health conditions resulting from mold in the home.

Summary of health problems

Many types of indoor mold, not just black mold, may cause health problems in some individuals.

Long-term exposure to high levels of mold in the home, however, can be unhealthy for any person.

People who are most at risk of the symptoms of mold exposure are:

  • infants and children
  • older adults
  • people with allergies or asthma
  • people with weakened immune systems

The main health risks related to mold exposure are allergies and irritation, which typically cause respiratory symptoms.

People with weakened immune systems may also have a risk of fungal infection.

A doctor may diagnose a mold allergy according to a person’s symptoms and their medical and family histories.

They may also perform tests. These include a skin prick test to check for reactions to common allergens, and blood tests to measure the immune system’s response to mold and check for allergies to specific types of mold.

A doctor may take a blood sample to diagnose a systemic fungal infection in someone with a weakened immune system. In some cases, further testing may be necessary.

Treatment for a mold allergy is similar to treatment for other types of airborne allergens. Options include:

  • avoiding the allergen whenever possible
  • taking a shower after coming indoors
  • reducing humidity in the home
  • replacing carpet with flooring that will not retain moisture, particularly in a basement
  • taking antihistamines
  • using steroid or antihistamine nasal sprays
  • using eye drops

For a long-term solution, a doctor may recommend immunotherapy. This involves getting a series of allergy shots over a few years.

Immunotherapy can be highly effective, but it is only suitable for certain types of mold allergies.

Individuals should treat all molds the same when it comes to removing them from the home.

The CDC recommends:

  • removing visible mold growth from hard surfaces with a commercial mold removal product, hot soapy water, or a mixture of 1 cup of bleach per gallon of water. A person should not mix bleach with other cleaning products
  • removing and discarding soft or porous materials — such as carpets, insulation, or wallboard — that show signs of mold
  • wearing protective clothing while cleaning, such as rubber boots, rubber gloves, and goggles

A person may also consider contacting a professional if there is extensive mold growth in the home or if a person has allergic reactions when cleaning moldy surfaces.

Mold thrives in damp and humid environments.

The most effective way to prevent mold growth is to monitor the humidity level in the home. It should be no higher than 50% throughout the day.

A person should check the humidity level regularly, as it can change every few hours. They may also use a dehumidifier if necessary, especially during humid months.

To prevent mold, a person can also:

  • regularly inspect the building for signs of water damage and mold
  • clean the bathroom regularly and tackle mold and mildew as soon as it appears
  • use exhaust fans in the kitchen and bathroom or open windows to improve ventilation
  • install an air conditioner with a high-efficiency particulate air filter — better known as a HEPA filter — to remove mold spores from the air
  • add mold inhibitors to paints to stop mold growth on walls and ceilings
  • avoid using carpet in the kitchen, basement, or bathroom
  • recycle old books and newspapers, as these can become moldy quickly if they get damp
  • deal with any flooding promptly by drying out soft furnishings and cleaning wet items with commercial products
  • dispose of flood-damaged carpets

To prevent or reduce the symptoms of a mold allergy, a person may:

  • close the windows at night if it is cold outside to reduce dampness
  • wear a dust mask while gardening
  • stay indoors after a rainstorm, in damp weather, and at other times when the mold count is high

A person should also use proper safety equipment when cleaning up mold in an industrial setting or after a natural disaster.

On the basis of current research, black mold exposure is no more dangerous than any other type of mold exposure.

It is impossible to avoid exposure to mold — the spores are almost everywhere in the atmosphere.

In high amounts or in people with allergies, exposure to any mold may cause allergy symptoms. In people with underlying health conditions, it may lead to more serious complications.

Regardless of the type of mold, it is important to remove it from the home for hygiene and health reasons.

Anyone with concerns about the effects of mold on their health should speak with a doctor.

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