Is black mould impacting your health? 10 symptoms to look out for


We speak to physician Dr Blen Tesfu and identify the warning signs of black mould toxicity and the impacts of short vs long-term exposure


a woman cleaning in the living room of her home.© Getty Images
November 28, 2025
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In damp, dark corners of your home, a black fungus could be plaguing your household and impacting your health without you even realising. 

Whether you are totally aware of what black mould is or not, chances are you've probably heard warnings about how it can be harmful. 

Black mould thrives in moist, poorly ventilated spaces and while it might seem like a mere inconvenience, the effects it can have on your well-being can be dangerous and long-lasting. 

From respiratory issues to skin irritation and even more serious chronic conditions, the risks are real, especially for children, the elderly, and those living with already existing health concerns. 

However, never fear, HELLO! has explored in depth the symptoms of black mould and how to alleviate them with the help of the expert tips and tricks so you'll know exactly what to do if you spot it in your home. 

Is it harmful to breathe in black mould?

Breathing in black mould isn’t just unpleasant, it can be dangerous if you're inhaling it over a long period of time. 

While a small patch of mould seems harmless, it is the spores you need to worry about as the patch starts to release them into the air, causing a range of health issues. 

For most people, the initial symptoms are usually mild and include a scratchy throat, persistent coughing, or sneezing. 

However, if you're someone who suffers with asthma, allergies, or a weak immune system, the symptoms could be much more severe, potentially triggering wheezing, shortness of breath, and even tightness of the chest. 

In some cases, if you are exposed to black mould for an extended period and it goes undetected, you may develop serious respiratory conditions, such as bronchitis or pneumonia. 

Physician Dr Blen Tesfu told HELLO!: "Even breathing in the mould spores of any colour (including so-called 'black mould') can irritate the upper respiratory tract in many persons, especially those with asthma, allergies, chronic lung conditions or immunocompromised status. 

"Symptoms can consist of coughing, sneezing, a runny or stuffy nose, a sore throat, wheezing, and irritated eyes or skin."

She continued: "For those who are susceptible to developing a reaction to mould spores, mould exposure can induce an asthmatic attack or exacerbate their pre-existing respiratory condition(s)."

© Getty Images
Black mould grows in damp, dark corners of homes

Can I stay in a property with black mould?

Choosing to live or continuing to stay in a property with black mould is not a decision you should take lightly. 

While the occasional spot of mould may not cause immediate harm, it is the continuous exposure to black mould that could exacerbate health conditions and damage a healthy immune system. 

If the mould growth seems to be isolated in one spot and you can clean it up safely, you might be able to stay as long as it doesn't grow back. 

However, if mould is widespread or you're experiencing symptoms like coughing, headaches, or skin irritation, it is definitely best to find alternative accommodation until the problem is fully solved. 

Dr Blen added: "Generally, most healthy adults should not be overly concerned about a short period of time around a small, isolated mould source in a very well-ventilated, very dry house that is dealt with promptly. 

"Long-term exposure to widespread, repetitive, or unapparent mould growth, particularly in bedrooms and living rooms, is not advisable for most, however, especially for young children, older adults, pregnant individuals, or those with lung issues or weakened immune systems."

The expert went on to explain: "Long-term exposure to a mould problem that has spread over a wide area, continues to grow back after repeated cleaning, and/or is associated with water damage (leaks) or structural dampness, should be viewed as both a housing and a health issue rather than simply a cosmetic issue."

How can I have mould professionally removed?

There are a multitude of ways to remove mould from your home but if you want to ensure it is safely and definitely gotten rid of, going the professional route might be the answer. 

"The majority of individuals are able to safely clean smaller patchy mould from non-porous surfaces (i.e., tile) by following their local health guidelines in combination with wearing suitable protective equipment," Dr Blen suggested. 

She expanded: "However, for large surface areas that have had repeated mould growth; mould on porous items (drywall, insulation, carpeting, ceiling tiles); etc. a certified mould remediation specialist or building hygienist should be hired to evaluate the root cause of the moisture problem, assess the amount of contamination (including any potential hidden mould); and develop a strategy for its safe removal." 

© Getty Images
If you are going to remove it yourself you need to wear gloves, a mask and goggles

How quickly can it harm you, and what kills mould?

The speed at which black mould can become a health risk depends entirely on how much exposure you have to it and the state of your health at the time you come into contact with it. 

If you have allergies or asthma, you might start seeing symptoms within a few days as the spores trigger a reaction. 

For those with weaker immune systems, these initial symptoms could escalate into bigger health issues quickly if left untreated. 

On the other hand, if you are healthy and have no health conditions, your symptoms may take a lot longer to appear, if they appear at all. 

While bleach works on tiles, experts recommend white vinegar or a dedicated fungicidal wash for porous surfaces like walls, as bleach often fails to kill the roots.

What are the 10 warning signs of toxicity?

While there are many symptoms of mould toxicity, and they may differ from person to person, if you are experiencing any of the below, you should seek medical help before things escalate. 

The 10 warning signs of toxicity are: 

  1. Fatigue and weakness
  2. Muscle aches and joint pain 
  3. Sleep disruption 
  4. Sinus issues 
  5. Persistent headaches or migraines 
  6. Respiratory problems 
  7. Allergic reactions 
  8. Mental and mood changes
  9. Gastrointestinal problems 
  10. Neurological and cognitive issues

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