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Is Yellow Mould Dangerous?

yellow mould

Whether you find yellow mould in your basement, outside your home, in the ceiling or even in your food, not only is it an inconvenience, but it can pose harmful health risks. If not completely eradicated, yellow mould will eat its way through your household and can even cause serious infections. 

The danger of yellow mould will depend on its size and species, so it can be useful to understand what causes it to grow, where it is likely to spread, and how to remove it. Let’s take a closer look at what yellow mould is and how to prevent it.

What is yellow mould? 

Similar to most other mould types, yellow mould is classified as a fungus and a living organism that works to break down organic matter. In turn, yellow mould needs three things to survive: moisture, organic matter, and the ideal temperature. 

Yellow mould will appear as different shades on the yellow spectrum, from brightly coloured to dull and muted, while its texture can either be dusty, fuzzy or even slimy. Some species of yellow mould thrive more in cooler, dark environments rather than humid or warmer climates.

Are there different types of yellow mould? 

Yes. There are many species of mould that can take on a yellow hue, some of the most common species include: 

Aspergillus: One of the most common species of mould, Aspergillus often thrives in warm and humid environments with plenty of moisture. They are known to trigger allergies and are related to respiratory issues so be careful not come into contact with it. It is also known to generate poisonous mycotoxins, which can cause a number of serious health concerns if ingested or frequently inhaled. 

Mucor: Mucor appears yellow during its advanced stages before turning a grey colour. Mucur is one of the more dangerous species of yellow mould and can cause an infection in the sinuses, brain and lungs known as mucormycosis. 

Surpula Lacrymans: Most commonly found in wood, this species causes severe dry rot and can eat its way through wooden structures.

Epicoccum Nigrum: This species doesn’t necessarily need warm temperatures to thrive and is commonly found on household surfaces such as carpets, walls and mattresses. E. nigrum strain can appear yellow, orange or even brown. 

Cladosporium: This can appear as white, turning yellow as it matures. This is commonly found on surfaces in the bathroom and other warm, moist environments. 

Geomyces Pannorum: More common in the northern hemisphere and can prefer colder climates over warm environments. You’ll generally find this species on a variety of household surfaces such as paper, flooring, wood and the walls. 

It can be impossible to accurately identify the strain of mould through a visual inspection due to the large number of variants. If you are concerned that you have a yellow mould infestation, it is recommended to seek out a professional mould removalist to treat and eradicate the mould to avoid risking your health.

Where can yellow mould grow? 

Similar to other species, yellow mould thrives in dark, often humid, moist environments, making it very common in bathrooms, basements, ceilings, walls and crawl spaces. The most common places yellow mould can appear include: 


Moist foods kept at room temperature are the perfect environment for mould to spread. Bread is a common food to attract mould due to its naturally high moisture content.  


Yellow mould is commonly found on decomposing organic matter such as dead leaves, on the soil, underneath plants or any other kind of natural materials. 


If you find yellow mould in wood, especially if it’s growing throughout your home, you will need to seek a professional mould removalist to eradicate the problem to avoid it causing dry rot. Yellow mould can often appear slimy and can easily eat its way through the structural integrity of wood within the home. 


Mould in the bathroom is common due to its naturally moist environment, especially when it lacks regular ventilation. Yellow mould, particularly Aspergillus, will attach onto the surfaces when there is water damage present. 

Basement/crawl spaces

Yellow mould will thrive in dark, humid environments that have very little exposure to natural light or air circulation. In these cases, yellow mould can be found on the carpet, walls, fabrics, furniture or any other organic materials found within a basement. 

How to remove yellow mould 

Yellow mould can be incredibly tricky to completely remove without a professional mould removalist, especially when there is an underlying cause for the infestation, such as leakage or water damage.

Because yellow mould thrives in dark, moist spaces, it can be hard to see the full extent of its growth as it can commonly appear underneath carpets, inside ducts, in crawl spaces, and basements. If you attempt to remove the mould, you are also at risk of circulating its spores to travel and fester into other areas of the home. However, if you do attempt to remove the mould, make sure you are wearing a protective mask and gloves to prevent coming into contact with and breathing in its spores. 

If you notice yellow mould growing in your home, it is highly recommended to seek out a professional mould removal service to inspect, identify, treat and remove the mould. 

How to prevent yellow mould

Yellow mould will thrive anywhere that has a high level of moisture and little light and inadequate ventilation. Here are some ways to prevent mould from growing in your home: 

  • Ensure your bathroom is well ventilated 
  • Keep all areas of the home dry 
  • Circulate the air regularly, especially in dark, naturally damp areas 
  • Clean and dry any flooding, spills or water damage promptly
  • Regularly clean out external drainage, guttering, downpipes and eaves 
  • Fix any leaking or plumbing problems promptly

Can yellow mould affect your health? 

There is a large variety of yellow mould species, some of which are toxic and very harmful to your health if you come into contact with it or breathe in its spores. Because it is unlikely that you will be able to identify what species of yellow mould you have, it is recommended to not come into contact with it and seek out a professional for advice. 

In any case, if you notice yellow mould growing within the house, especially if found in wood or the structure of the home, you should take action to remove the mould to prevent the infestation from worsening. If found on your food, you should discard the food in its entirety, as ingestion can cause infections and other serious health concerns. 

Some species of yellow mould can be known to trigger allergies and worsen existing respiratory issues, so it’s important to avoid breathing in its spores. Some common symptoms for those who are overexposed to mould can include: 

  • Headaches 
  • Coughing
  • Sneezing
  • Dizziness
  • Wheezing 
  • Rashes or inflammation 
  • Mucormycosis 

If you are experiencing any severe allergic reactions or infections, please see your GP or healthcare professional immediately for further advice. It is also recommended to seek out a professional mould removalist for a long-term solution plan. 

When to Call a Mould Removal Professional? 

Yellow mould can be tricky to identify and some species are toxic and are dangerous to your health. If you come across yellow mould growing in your home, you should seek action for its eradication to prevent overexposure and infestation. 

If you are afraid of mould becoming a problem in your home and are looking for a long-term solution, be sure to call upon a professional team to help you. The MouldMen team will inspect, treat, and provide you with a Mould Management and Prevention Plan to ensure that your home is kept safe and free from mould. Call us on 1300 60 59 60 or click on the link below to book your free inspection today. 

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