Can Black Mold Kill You?

Medically Reviewed by Jabeen Begum, MD on May 27, 2024
Written by Stephanie Booth
9 min read

Stachybotrys chartarum is sometimes referred to as "toxic black mold." But all kinds of mold can cause symptoms if you're sensitive to, or allergic to, mold.

More research is needed to understand how this specific type of black mold can affect your health. However, it's important to get rid of it if you find it in your home.

Stachybotrys chartarum is a common black mold. It can also be a dark greenish color. It's naturally found in nature, but can also grow on cotton, wood, and paper products if the conditions are right. It sometimes produces toxic chemicals that are found in its airborne spores and fungus fragments. These are called mycotoxins. While there's no clear link to Stachybotrys chartarum mycotoxins and deadly diseases, breathing them in or touching them may cause symptoms, especially in people with allergies, asthma, and weakened immune systems.

Even if you're in good health, mold should always be removed from your home.

Black mold vs. mildew

Mildew and black mold are both fungi, and technically, they're both molds. But mildew is usually white.

Molds are an important part of our environment. Among other things, they help decompose (break down) dead plants and trees. Molds reproduce by tiny spores that float through the air and land on surfaces. They can easily enter your house through an open window or door, or by clinging to your shoes or your pet's fur. That's not necessarily a problem unless the mold finds a good place to stay put and grow.

Mold spreads quickly indoors in the right conditions, which include:

  • Moisture level (humidity) at or over 70%
  • Adequate food source (such as drywall)
  • Oxygen
  • Temperatures that range from 40 to 100 F

Mold can grow anywhere in your house that provides these four things. 

The most likely places mold will grow are:

  • Any area where there's been a water leak or flooding
  • Damp rooms without adequate air ventilation, such as bathrooms
  • Basements where humidity tends to be higher
  • Any areas with a lot of water condensation

Mold can cause your immune system to react. This is most likely to happen if you're allergic to mold, exposed to large quantities, or for long periods. An example is farmers who work with a large amount of moldy hay. The most common symptoms of mold exposure include:

Respiratory symptoms of black mold

If you have asthma, being around mold may trigger an attack. Symptoms of a mold-induced asthma attack can include any of the following: 

It appears to be very rare for black mold to cause severe illness or be fatal. But if you have a weakened immune system or lung disease, being around mold could lead to a serious lung infection called mycosis.

The signs can include:

  • Coughing (you may cough up blood)
  • Fever
  • Feeling tired even after resting
  • Joint and muscle pain
  • Headache
  • Night sweats

If you have any of these symptoms, see your doctor. Make sure to tell them you've been exposed to mold.

Black mold poisoning symptoms

Sick building syndrome (SBS) is a group of symptoms that are most common in people who work in certain office buildings. The symptoms include:

  • Gastrointestinal issues
  • Fever
  • Chills
  • Trouble concentrating
  • Dry skin
  • Stiff joints

If you have these symptoms when you're inside a building and they get better after you leave, you may have SBS.

Mold is believed to play a role in this complex condition. But many other things could also be to blame, such as poor air circulation, dust, carpet fibers, or bright or flickering office lights.

So far, the information about black mold and how it affects your health is limited.

Is black mold deadly?

For most people, being exposed to black mold may only cause mild respiratory systems, such as a runny nose. Experts don't agree on whether it can lead to more serious issues, such as pulmonary hemorrhage (bleeding in the lungs), which can be fatal. More studies need to be done.

If you have black mold in your house, it should be removed right away. Aside from any health concerns, it damages whatever it grows on and can affect the structure of your house.

Long-term effects of mold exposure

One study tracked 14 workers in a Finland hospital who were exposed to mold for many years. Initially, their health was good. But over time, four workers were diagnosed with asthma. One person had breathing issues that improved when they moved to another building. And many of the workers had frequent runny noses, coughs, sinus issues, fevers, and muscle aches.

Still, more studies are needed to clarify mold's long-term effects. One reason that's a challenge is that many other potential toxins thrive in the same damp indoor areas as black mold. Among them are bacteria, dust mites, and airborne chemicals and gasses that are released from the materials that the mold is growing on. Any or all of those items could be to blame for health issues, too.

It's also unclear how being exposed to mold makes it harder for you to get pregnant, increases the chances of miscarriage, or could cause birth defects. More studies need to be done to understand this better.

Is it dangerous to breathe in black mold?

If you have a mold allergy, your immune system will react to the tiny spores you breathe in. It will release different chemicals, including histamine, just like it would against any other allergen.

This can cause symptoms such as sneezing, watery eyes, itching, and an itchy skin rash.

If you have a severe mold allergy, your mouth or throat could begin to swell and you may have trouble breathing. If that's the case, call 911. If you know you have a severe mold allergy and carry an adrenaline injector (EpiPen), use that to reverse the allergic reaction while you wait for help to arrive.

What is toxic mold syndrome?

This isn't an official diagnosis. It's the name for a group of symptoms that range from lack of focus and fatigue to muscle aches. Some people believe that they're caused by indoor black mold. The theory is that mycotoxins may cause chronic inflammation, especially in people with weakened immune systems.

But there's not enough evidence to prove this. And not all experts believe toxic mold syndrome is real. One theory is that seeing black mold makes some people think they'll get sick, and that leads them to start having physical symptoms. This is a real phenomenon called a "nocebo effect".

Can black mold cause cancer?

Right now, no study has directly linked it to cancer. But research about the health effects of mold is ongoing.

Indoors, black mold is often found on materials that have high wood or paper content, such as wallboard, wallpaper, or certain kinds of insulation. The spores typically look slimy and sticky.

What does black mold smell like?

All molds release tiny microbial volatile organic compounds (mVOCs) into the air. This is what causes a strong musty, earthy smell.

Black mold test kit

Some mold test kits are available for sale. You'll also see ads for services that offer to test the type of mold you've found. But there are no national testing standards or reporting formats, so the results may not provide a lot of helpful information. No matter which type of mold you have in your home, you need to get it removed as soon as possible. Testing will only delay that from happening.

Black mold in the shower

This area is often damp, so it can be hard to keep your tub, shower, or bathroom completely mold-free.

Black mold in the basement

Plumbing leaks and flooding can quickly set the stage for mold in your cellar. Once an area gets wet, mold can start growing in as little as 24-48 hours.

Black mold on walls

Sometimes, you may not see mold, but you can smell it. It could be hiding inside your walls, behind wallpaper, above ceiling tiles, or inside ductwork.

The CDC does not advise having mold tested if you find it in your house. You'll need to get rid of it no matter what type it is.

If the area is small (less than 10 square feet), you may be able to remove the mold and fix the conditions (such as a water leak) that caused the mold to grow. But you'll need to clean very deeply and remove or replace parts of the mold-infested areas, such as wallboard or ceiling. Hiring a trained professional to tackle mold-infested areas is often a good idea, especially if the area is large.

Take precautions to protect yourself before you attempt to remove mold. As soon as you disturb the area, you'll release mold spores into the air. They could start to grow somewhere else.

Use an N-95 face mask to avoid breathing in mold spores. Wear gloves to protect your hands and goggles without ventilation holes to protect your eyes.

How to get rid of black mold on walls‌

The most important part of removing mold is finding and removing its water source. Mold can't grow without moisture. Keep the following tips in mind when you're cleaning up mold:

  • All items that have been wet for more than 48 hours need to be thrown away if they can't be well-cleaned and dried.
  • Don't paint or caulk over moldy surfaces. Remove the mold and dry the surfaces before painting them. Paint applied over the mold will peel.
  • Use plastic sheeting to block an area with mold from the rest of your house and keep the spores from spreading.
  • Scrub hard surfaces with mold with dish detergent and water. Dry them thoroughly.
  • Put any moldy items in a plastic bag before you take them out of the room to prevent mold spores from spreading.
  • Use a HEPA filter in your air conditioner and furnace to capture mold spores that may be airborne in your house.
  • Consult a specialist if you're not sure of the best way to clean a valuable or sentimental item.

How to remove black mold from shower

You can also use bleach to clean up hard surfaces, such as a shower. Add 1 cup of bleach or less to 1 gallon of water.

Be careful with bleach

Take the following extra precautions if you're using bleach to clean mold:

  • Never mix bleach with any other household cleaner, especially any containing ammonia. Mixing bleach and ammonia will produce a harmful poisonous gas.
  • Make sure you read and follow the manufacturer's directions on bleach or any other cleaning product.
  • Open your windows and doors to let in fresh air when you're using bleach.
  • Wear gloves and goggles to protect your skin and eyes from the bleach.

Black mold removal cost

The price to remove mold from your home will depend on the size of the affected area and the extent of the damage.

Make sure the professional you hire is trained in mold removal. Check their references and ask if they follow mold removal guidelines from trusted national organizations such as the Environmental Protection Agency (EPA).

Controlling moisture is the key to preventing mold from growing in your home. To keep mold from becoming a problem:

  • Keep the humidity in your house below 50%. Using an air conditioner or dehumidifier can help with this.
  • Make sure your house is clean, dry, and well-ventilated.
  • Fix any water leaks immediately.
  • Use ventilation fans in your kitchen and bathrooms. Opening a window will also help fresh air circulate.
  • Don't put carpet in rooms that are likely to become wet such as the basement, kitchen, or bathrooms.
  • Make sure wet floor mats are dried quickly.

Black mold can cause symptoms in some people, particularly if you have a mold allergy or a weakened immune system. More research needs to be done to better understand its other health effects. But whether you have black mold or another type in your house, it's important to safely remove it as soon as possible.