Orange Mold: What is it and is it Dangerous to Your Health?

By: Licensed Mold Assessor Brad Fishbein

January 7, 2022

Orange mold? Yes it exists mold is diverse!

In fact, it can appear as a few different colors. One of those colors is orange. Why?

In this blog post, we're going to explore what it means for mold to be orange. We're also going to cover:

  • What is orange mold
  • Where orange mold grows
  • How long it takes for orange mold to grow
  • If orange mold is dangerous
  • If orange mold can be cleaned (or remediated)

With so many topics to cover, we're just going to jump in! Let's start by understanding the different what orange mold actually is.

What Is Orange Mold?

Orange mold, scientifically classified within the Acremonium strictum group, is a type of fungus that thrives in moist and poorly lit conditions. It is characterized by its vibrant orange color and slimy texture, and is commonly found in soil, wood, and decaying plant matter. These molds can pose potential health risks and should be promptly identified and removed to prevent further damage.

Orange Mold Pic

Orange mold—like all mold—is a type of fungus found in decaying organic material such as food, wood, or fabric. It grows in damp areas and tends to form colonies of orange or yellowish-colored spots.

But, why does it appear to be orange in color? After all, the most common colors are black, gray, green, white, and brown.

This odd coloring is often caused by ingesting certain minerals from its environment when the mold absorbs them into its body cells. The color of mold is also determined by:

  • Region
  • Age

Regarding age, the orange color may appear when the mold growth is older. For example, the mold may first appear white or brown but turn orange over time.

Anyone walking into an environment where orange mold growth is present may be able to smell a musty odor that can indicate the presence of these fungi. Orange mold spores smells like a pair of wet, old shoes.

Types of orange mold include:

  • Trichia Varia
  • Fuligo Septica
  • Acremonium
  • Physarum polycephalum (when old)

Acremonium Strictum

This sly fungus is always up to no good, especially when it comes to people with weakened immune systems. It can cause a rare but serious type of fungal infection called hyalohyphomycosis, and it loves to hang out in soil, plant debris, and rotten mushrooms. Its colonies can be orange, pink, or yellow, so keep an eye out for this mischievous mold!

Epicoccum Nigrum

This asexual fungus is known for its bright pigments that give it yellow, red, and orange colors. It can infect plants and cause allergies in humans, but it's also used to control certain plant pathogens and improve indoor air quality. Just be sure to steer clear if you're allergic!


This group of molds is found all over the world and can grow on a variety of materials. Some types of Aspergillus produce mycotoxins, which can be harmful to your health. Aspergillus flavus is one of these toxic molds, and its colonies can appear orange-yellow. If you see it, call a professional to get rid of it fast! Keep an eye out for this mold, especially if you're storing food or have a damp basement.

Aspergillus Flavus

This mold growth is definitely not one you want to mess with! Its colonies can sometimes appear orange-yellow, and it's one of the several types of Aspergillus that produce harmful mycotoxins. These toxins, like aflatoxin B1 and B2, can cause serious liver damage and even cirrhosis. They can also suppress your immune system and increase your risk of cancer. If you see Aspergillus flavus in your home, call a professional to get rid of it ASAP!

What is Orange Slime Mold

Slime molds are unique organisms that are not quite fungi or animals. Slime mold spend most of their time as active cells hunting for food (bacteria), but transform into a plasmodium during cold weather to feed on organic matter and bacteria. In winter, they form sporocarps and harden until spring, when they release their spores and start the cycle again.

Some types of slime molds, like Fuligo septica and Tubifera ferruginosa, can appear orange when they're in their plasmodium or sporocarp stages. And even though slime molds aren't classified as human pathogens like regular molds, studies have shown that our bodies can react to their spores as allergens. In fact, 40% of people with seasonal allergies had positive skin test reactions to slime mold spores!

So, if you see some orange slime molds in your home, don't panic - they're not going to infect you with anything. But they can still cause allergic reactions, so it's a good idea to have them removed by a professional. And keep in mind that slime molds can make up to 25% of the mold presence in our homes, so it's always a good idea to be on the lookout for any unusual growths.


Where Orange Mold Grows

Orange mold growth can be found in homes and is caused by a variety of environmental factors. It grows on damp porous surfaces such as:

You'll typically find it in:

  • Attics
  • Basements
  • Gardens
  • Kitchens
  • Mulch
  • Wooden window sills

Orange mold is usually associated with bathrooms and basements due to humidity levels and dampness. Case in point: Orange streaks often indicate that it may exist near water sources. It also tends to grow on:

  • Painted surfaces
  • Walls behind showers or tubs
  • Window frames

Poor ventilation and inadequate air circulation often encourage its proliferation inside a home or building. Additionally, orange mold may be a result of water damage from floods, plumbing leaks, or broken pipes.

Finally, in outdoor areas, Serpula lacrymans is an orange mold that thrives in wet wooden structures like fences, decks, and outbuildings.

How Long Does it Take for Orange Mold to Grow?

When it comes to orange mold, just how long does it take for the growth process to occur? To accurately answer this question, you must consider numerous factors, including:

  • The amount of organic material present in the space
  • The level of contaminated water or moisture present
  • The humidity levels

Generally speaking, this type of mold will begin growing within 24 to 48 hours after a damp or wet space is exposed. That's fast!


What are the Dangers of Orange Mold?

It would be a mistake to think that orange mold is harmless if you don't touch it. However, the opposite is true. And it can cause a wide variety of health problems if left untreated. With orange mold—as with other types—the danger is in the air.

The spores from the growth can spread through the air if not contained and can cause allergic respiratory reactions for those with sensitive immune systems.

People with respiratory conditions such as asthma are especially vulnerable to these health effects because they are at an increased risk of inhaling the dangerous spores released by orange mold.

Additionally, those who come into contact with the spores through direct contact can experience skin irritations or allergic reactions like:

  • Sneezing
  • Coughing
  • Watery eyes

Long-term exposure to orange mold can even lead to neurological damage or heart disease. Therefore, it is important that any signs of orange mold growth are addressed immediately.

Finally, consider your own health and the health of anyone else who may be exposed to the mold. Children, the elderly, and people with weakened immune systems are more susceptible to mold-related illnesses.

If you or someone in your home has allergies or a suppressed immune system, it's especially important to have a professional check for mold. An inspection may uncover a serious hidden mold problem, and even if it doesn't, you'll have peace of mind knowing that your home is safe and healthy.


Does Orange Mold Need to be Remediated or Cleaned?

Orange mold can cause damage to your property. And, as mentioned earlier, can also lead to respiratory health issues.

Can you just clean it to fix the problem? Or, do you have to remediate the issue? Let's define each before moving forward.

  • Mold cleaning: Using baking soda, vinegar, or another substance to kill the mold and remove it from the surface.

  • Mold remediation: Removing the affected surface and material from the area.

So, remediation is obviously a surefire way to get the mold out. But, is it necessary? That depends.

For example, if the affected area is small (less than 10 square feet) and on the surface, cleaning may resolve the issue. However, if the orange mold is the result of water damage, remediation may be the better option. That's because the inner parts of the material could be affected, in which case it would all need to be replaced.

Let's examine the cleaning method more in detail.

How to Clean Orange Mold

The first step in removing orange mold is identifying the source of moisture (leaky pipe, etc) that is allowing the spores to grow and thrive in your home. Once you identify the source and correct it, you can clean up any existing orange mold growths.

Before you start, ensure you're using protective gear like gloves and a face mask. As mentioned before, you can use household products like baking soda and vinegar. The following also works to kill orange mold:

  • Detergent
  • Hydrogen peroxide
  • Cleaners made specifically for mold

Scrub off any visible growths with a soft brush or sponge before rinsing with warm water and drying completely with a towel or cloth.

Finally, use an air purifier designed for removing airborne particles such as dust mites and pollen to help get rid of any remaining spores that may still be floating around your home.

Prevent Orange Mold

The best way to prevent orange mold from taking root in your home is to ensure that any moist areas are dried quickly.

If you've got some pesky orange mold hanging around your home, don't worry - there are plenty of ways to get rid of it!

Mold in Toilet Bowl

In the toilet, you can use:

  • Bleach
  • Vinegar
  • Hydrogen peroxide

If you have a toilet in your home that you do not use often, flushing it once and a while will help prevent mold growth.

Mold In Kitchen

In the fridge, toss any old foods away from time to time. To prevent surface mold growth give the inside a good scrub with one of the cleaning solutions mentioned above.

If you've got a water filter or water softener, make sure to change it on schedule. For your water filter consider using an oxidizing filter to help with any organic materials.

Don't let water sit in your coffee machine water reservoir be sure to give it a good clean every so often. I know there are many different ways to prepare coffee... but mold growth inside of my coffee is one recipe I'll skip thank you very much.

Orange Mold on Wood

Don't make this mistake: Never use bleach for orange mold removal on wood. Bleach is made up of chlorine and water, and while it's great at killing surface-level mold, it won't do much to eliminate the roots. Plus, the water in the bleach can actually soak into the wood, providing even more moisture for mold to grow on.

Orange Mold Infestation

If you've got a larger mold problem (more than 10 square feet), the Environmental Protection Agency (EPA) recommends calling in a professional mold removal company. And if you think the mold might be lurking in your HVAC system, it's best to leave that to the experts as it's not worth the health risks.

Meet the author: Brad Fishbein is an ACAC council-certified Microbial Investigator. In the fall of 2012, he became a Licensed Mold Assessor in the State of Florida through the Department of Business & Professional Regulation. Brad has helped homeowners with over 5,000 successfully completed Mold Inspections since 2009.

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