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Is Brown Mould Dangerous?

Mould is a common issue in most households so when it begins to spread it can be difficult to eradicate completely. Brown mould will present in a variety of tones, textures and sizes and is very common in households with high levels of moisture. 

Because brown mould is apparent in multiple strains, how dangerous it is can differ depending on its strain and level of infestation. Here is some helpful information about what brown mould is, if it is dangerous, and what to do if you find it.

What is brown mould? 

Brown mould is a fungus and a living organism that relies on organic matter, water and oxygen to thrive. It is a combination of several species of mould and frequents areas that are prone or are experiencing severe water damage or leak problems. 

If you find discoloured, dark patches on your walls, often appearing in clusters, chances are you have brown mould. Despite its name, brown mould often holds a spectrum of colours visible to the naked eye, spanning from a beige/tan colour to yellow or even black. Brown mould is also associated with a deep musty smell and is known to release visible spores into the air. 

Brown mould can be difficult to remove completely so if you are worried that brown mould is spreading around the home, it is recommended to call a professional mould removal service. 

Are there different types of brown mould? 

Yes. Brown mould is often a combination of multiple mould species and is very difficult to identify purely from a visual examination. Here are some of the most common types of brown mould found within the home: 

Stemonitis: Found in bathrooms or rotting wood, this species thrives in damp conditions and has a slimy texture with hairy, feather-like threads. 

Cladosporium: This species is often dark brown or black, releases dark spores and is very common in heavily humid or water damaged areas. If left untreated, it can cause health problems such as asthma, respiratory issues and even severe infections.  

Ulocladium: Thrives in severe water damaged environments and is known to be quite dangerous, inducing allergic reactions, illnesses and can even be fatal. 

Aureobasidium Pullulans: Spanning from pink to black, this strain is often found growing in a variety of environments and is known to cause illnesses – posing a particular threat to those with underlying respiratory issues. 

Taeoniella: Can appear as brown or black in colour and is often found in wood and is a common cause of wood rot. 

Where can brown mould grow? 

Brown mould can be dangerous if left untreated or there is an overexposure in the home so it’s important to address any leaks or plumbing issues promptly to avoid brown mould becoming a problem. Brown mould is usually found in the following places: 


With naturally high levels of moisture, bathrooms are an ideal space for most moulds to grow and spread. If brown mould is found in the bathroom it is usually a sign of a larger problem that needs addressing. Brown mould will present itself as a slimy wet or fuzzy substance, commonly found in between tiles, window sills, or bathroom mats. 


If wood is exposed to excess amounts of water, it becomes soft and damp, making it perfect for brown mould to grow. Wood is usually found frequently around the home and often forms part of its structure so it’s important to fix any water damage to prevent the mould from spreading and damaging its structural integrity.

Walls and Ceilings

Commonly found in structures with poor lighting or severe leakage problems, brown mould can find itself on walls, basements or on the ceiling – anywhere that can be dark and damp. Brown mould will usually appear as dark spots and can even develop growths depending on how advanced it is. Brown mould can also start on the inside of walls and work its way to the outside so if you see start to it, it usually means there is a larger infestation. 

How to remove brown mould

Brown mould is usually a sign of severe plumbing problems, water damage or excess moisture in the home. Therefore, its severity is not always visible around the home.

If brown mould begins to present itself on or behind the walls or in the bathroom, it usually means that the severity of it is worse than it presents. In turn, attempts to remove brown mould are usually redundant without addressing the cause of the mould and will result in the mould coming back until the problem is fixed. 

Lastly, by coming into contact with brown mould, even with the use of protective gloves, there is still a risk of spreading the mould or its spores into other areas of the house to manifest and grow. 

Because it can be tricky to identify and remove, it’s important to address what is causing the mould and to seek out a professional opinion for effective treatment and future prevention

Can brown mould affect your health? 

Because brown mould is associated with a variety of mould species, its danger rating can vary depending on its species and is near impossible to identify visually without a lab analysis. Some variants of brown mould have been associated with severe illness and fatality, so it’s important to seek out professional mould removalists if you believe you have brown mould in your home. 

You should take action to remove mould from your home as soon as you can notice it to prevent long term exposure. Small amounts of brown mould may not pose an immediate threat, but it can be a health risk for those with underlying respiratory issues or allergies. If brown mould is left untreated it can increase in severity and become a serious health risk for those who come into contact with or breathe in its spores. 

Some common symptoms for those who are overexposed to mould can include: 

  • Headaches 
  • Coughing
  • Wheezing 
  • Rashes or inflammation 
  • Dizziness
  • Sneezing
  • Eye irritations 
  • Allergic reactions

If you are experiencing any severe allergic reactions, infections or  symptoms, please see your GP or healthcare professional 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? 

Brown mould can be hard to identify and even harder to remove completely. Often appearing as brown, beige and black, brown mould is often associated with excess water damage and plumbing problems and can quickly turn into a serious health risk if not treated correctly.

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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