A gloved hand points to spots of greenish mold on an indoor wall. Share on Pinterest
Andrey Popov/Getty Images

You’re likely to find mold growing in the darkest, dampest spaces. More than a cosmetic problem, mold can damage your home and contribute to health issues.

Let’s examine the types of mold you’re most likely to find in your home, the potential effects on your health, and how to get rid of mold.

Mold is an organism that’s part of the fungi family. It grows indoors as well as outdoors.

Outside, molds are an important part of the ecosystem. They help break down plant and animal matter. When mold grows inside, it can sometimes be problematic. It can cause allergies and infections in some people.

Types of mold

Multiple types of mold can grow in the same area. You can’t always tell the difference between types of mold without testing. Fortunately, you don’t need to know the type of mold to get rid of it.

The most common indoor molds are:

  • Cladosporium. This mold is brown, green, or black. Cladosporium grows in both warm and cool locations. It’s most often found on wood, carpets, or fabrics, and in heating and cooling ducts.
  • Penicillium. This fuzzy mold is blue, green, or yellow. It’s often found under carpets, in basements, and in insulation, especially when there’s been water damage.
  • Aspergillus. Aspergillus is green, white, or gray with dark spots and a powdery look. This type of mold doesn’t need much ventilation. It thrives in fabrics, walls, attics, and basements, as well as on dry food items.

There are other molds that aren’t found indoors as often as those listed above, but you may still find them in your home. These include:

  • Alternaria. This fuzzy mold is white with black spots. It tends to grow in fabrics and wallpaper, near windows and air conditioners, and in bathrooms and kitchens.
  • Aureobasidium. This mold is pink with black spots. It’s most commonly found on wood, walls, caulking, and grout.
  • Stachybotrys chartarum. Also called black mold, this greenish-black mold grows on things with a high cellulose content. It’s usually found on paper, fiberboard, and gypsum board (drywall).
  • Trichoderma. This mold is creamy white but turns green when it releases spores. It’s often found on wood, windows, and in bathrooms and kitchens.

Having mold in your home won’t necessarily make you sick, but it does have the potential to cause certain health issues.

Touching or inhaling mold spores can cause allergy-like symptoms such as:

  • runny nose and congestion
  • eye irritation
  • sneezing
  • coughing
  • sore throat
  • skin rash
  • headache
  • lung irritation
  • wheezing

Mold exposure is not an emergency for most people. However, you should let your doctor know if you have a health condition that puts you at greater risk of complications and you believe you’re experiencing symptoms of a mold-related infection. Read more about mold-exposure complications below.

Mold can be black, white, spotted, or just about any color. It may appear powdery, cottony, or velvety.

If you notice a spot and aren’t sure if it’s just an old stain or a splotch of dirt, here’s how to tell if it could be a sign of a mold problem:

  • It has a musty, earthy smell.
  • There’s a nearby source of moisture, but not much light.
  • You see warping, cracking, or peeling of whatever material it’s growing on.
  • A drop of bleach lightens its color in a minute or two.
  • Unchecked mold will continue to grow. Dirt and old stains won’t.

How common is mold in buildings?

Mold is very common in homes and buildings.

One 2017 study found mold in every public building studied, with an average of about 14 instances of mold per building.

Another 2012 review study involving 31 European countries found mold in 1 in 6 homes. The author noted that the prevalence of mold may vary greatly depending on the regional climate.

How does mold get indoors?

Outdoor molds release tiny spores that float through the air. These spores can enter your home via:

  • doors
  • windows
  • heating and air conditioning vents
  • clothing and shoes
  • pets

Once mold spores get inside, they can grow in the right conditions.

Mold spores grow in spaces with moisture, such as:

  • in sinks, bathtubs, and showers
  • near leaky pipes
  • around windows
  • in basements, crawl spaces, and attics

They can latch onto a variety of materials, including:

  • fabrics
  • carpet
  • paper
  • wood
  • ceiling tiles
  • dust
  • paint
  • wallpaper
  • insulation

How do you know if you have a mold problem?

Anytime you see or smell mold in your house, it’s a problem. All types of mold can potentially cause health issues and need to be removed.

Mold starts out as a little spot but grows quickly. You’ll usually notice it early on, unless it’s in an out-of-the-way location.

Mold is everywhere, and everyone breathes in mold spores. Mold allergies occur when your immune system overreacts to certain types of mold, which your body considers to be an allergen. This can result in symptoms such as sneezing and nasal congestion.

Not all molds cause allergy symptoms. The most common types of molds causing allergy symptoms are:

  • Alternaria
  • Aspergillus
  • Cladosporium
  • Penicillium

Risk factors

You may be more likely to develop a mold allergy or experience mold allergy symptoms if you:

  • have a family history of allergies
  • work or live in a building that has greater than 50 percent humidity or poor ventilation
  • work or live in an environment that’s been flooded, has leaky pipes, or is otherwise exposed to extreme moisture
  • work in a job where you’re more likely to be exposed to mold, such as:
    • farmworkers
    • lumber millers
    • woodworkers
    • winemakers

If you believe you’re having symptoms of mold exposure, let a doctor know. It can be hard to tell if mold, another condition, or a type of allergy is causing your symptoms. Your doctor may offer you skin or blood tests to determine whether you truly have a mold allergy.

Treatments and preventative steps for mold allergies may include:

  • medications, including nasal corticosteroid sprays and antihistamines
  • allergy shots, which may be especially appropriate if you experience severe symptoms year-round
  • managing humidity at home, including:
    • maintaining the humidity below 50 percent with a dehumidifier
    • regularly cleaning damp areas, such as basements and bathrooms
    • keeping humid areas well ventilated
    • quickly repairing any leaks

What helps with mold-induced nasal and sinus symptoms?

Some types of over-the-counter (OTC) medications may help relieve mild to moderate symptoms linked to mold exposure. These medications include:

If you have more severe symptoms, be sure to reach out to a healthcare professional.

Most people may only experience an allergic reaction or allergy-like symptoms following mold exposure. More rarely, mold can cause more serious health issues in some people with certain risk factors.

Infections

Most people regularly breathe in mold spores without experiencing any health complications. However, people with certain health conditions may be at risk of a lung infection or other infections from inhaling certain types of mold.

Examples of mold-related infections include:

You may be at a higher risk of these illnesses if you have conditions such as:

Asthma

In people with asthma, an allergic reaction to mold may trigger an attack. They may need inhalers to manage symptoms.

Some researchers have also found that high levels of mold in homes may be a risk factor of asthma in school aged children.

Pneumonitis

Exposure to a large amount of mold can sometimes cause a more serious reaction known as hypersensitivitypneumonitis. This type of exposure is usually due to occupational or workplace hazards rather than from exposure to mold in your home.

Other complications

There have been rumors linking black mold exposure to health issues such as memory loss and headaches. This was thought to be because black mold spores release toxic compounds called mycotoxins. However, experts generally agree that black mold is not linked to an increased risk of specific health issues.

A 2017 study found no proof that black mold exposure causes health problems. Another 2019 study emphasized that mycotoxins in the air have not been linked to disease.

In many cases, you can get rid of household mold yourself. Mold can be removed with:

  • commercial products
  • soap and water
  • a bleach solution of no more than 1 cup of bleach per 1 gallon of water

Before you begin:

  • Open any windows.
  • Wear protective eyewear, nonporous gloves, and a face mask or N95 respirator.
  • Never mix other cleaners or ammonia with bleach, as it can create toxic fumes.

Use a brush to scrub mold off surfaces, making sure you get it all. Porous materials, such as carpeting, furniture, and ceiling tiles, may have to be thrown out. Don’t paint or caulk until you’re sure all the mold is gone.

Seek a professional contractor with experience in safe removal of mold if:

  • there’s a large amount of mold or it’s hard to reach
  • you’ve had severe water damage
  • you’re at high risk of symptoms from mold spores

Mold spores are everywhere and are part of the world we live in. It’s impossible to get rid of mold entirely, but there are ways to make your home unsuitable to mold. This includes taking the following steps:

  • Fix water leaks immediately. Clean up excess water and use fans to dry the area.
  • Repair or replace windows that leak or sweat, as moisture may collect on the frame and sill.
  • Maintain 50 percent humidity or lower in your home with air conditioners and dehumidifiers. Change filters and service air conditioners and furnaces as recommended.
  • Don’t carpet rooms such as bathrooms, laundry rooms, or basements.
  • Keep your home well ventilated. When possible, exhaust fans should vent outside. Use exhaust fans or open windows when showering or bathing.
  • Use cleaning products that kill mold. Wipe down tiles and allow shower curtains to dry.
  • Don’t leave wet towels or clothes in a pile or sitting in a laundry hamper or washing machine.
  • Make sure water drains away from your house.
  • Use mold inhibitors in wall paints. Be sure surfaces are dry before applying paint.

Mold in your home doesn’t always cause health problems, but it should always be removed. Mold can cause damage to your home and can lead to irritation in the:

  • eyes
  • nose
  • throat
  • lungs

If you have a mold allergy or chronic lung condition such as asthma, you’re at risk of more severe symptoms and complications.

A few home maintenance chores can make it harder for mold to grow indoors. If you happen to have spots of mold in your home, you can take steps to remove the mold yourself. If it’s a big job, or if you have respiratory problems, a professional contractor can safely remove mold and make the necessary repairs.