Symptoms of Black Mould: What You Need to Know

Understanding the Symptoms of Black Mould in Your Home

That musty smell in your bedroom might seem harmless at first, just a sign your home needs airing out, but it can point to something more serious.

Guidance from the Government, health bodies, and wider reporting around black mould highlights the impact it can have on respiratory health, especially for children, older people, and those with existing conditions.

This has become a growing focus in rental properties, with increased scrutiny on living conditions and legislation such as Awaab’s Law. Recognising and acting on the symptoms of black mould is more important than ever.

This guide explains what black mould is, what causes it, and the symptoms of black mould sickness to look out for. It also looks at how issues like mould in the bedroom or fungus on walls develop, and why early identification of both symptoms and environmental conditions is key to preventing more serious problems.

What Is Black Mould?

Black mould is a type of fungus that thrives in damp, poorly ventilated areas, often growing on walls, ceilings, and around windows. As it spreads, it releases microscopic spores into the air you breathe every day. 

For many people, the effects begin subtly, with symptoms like a lingering cough, fatigue, or irritated skin, before potentially developing into more serious health issues. Understanding what black mould is and how it affects your body is key, because what you cannot always see could be impacting your health far more than you realise.

Monitoring humidity and temperature is a vital component to identifying the rise of black mould in a property before it appears, and prevention is the safest way to treat black mould.

Black Mould in the Wake of Awaab’s Law

Having drawn on industry guidance, housing standards, and insights from monitoring conditions across UK homes, it is clear that damp and mould are no longer issues that can be addressed reactively.

As of October 2025, Awaab’s Law has officially come into force for social housing in England. This law ensures that landlords can no longer ignore reports of damp and mould, setting strict, legally binding timelines for action. Under Awaab’s Law, if you report damp or mould, your landlord must follow these specific timeframes:

• Investigate within 10 working days: Once you report a potential hazard, the landlord has 10 days to assess the issue.
• Provide a written report: Within 3 working days of the investigation, you must receive a written summary of what they found and what they plan to do.
• Fix “Significant Hazards” within 5 days: If the investigation confirms a significant risk to your health, repairs must begin within 5 working days.
• 24-hour Emergency Response: If the mould or damp is classified as an “emergency hazard” (posing an imminent risk to your safety), they must make the property safe within 24 hours.

No More “Lifestyle” Excuses

One of the biggest shifts under Awaab’s Law is the end of “blaming the tenant.” Landlords are now legally discouraged from dismissing mould as a result of “lifestyle choices” (like drying clothes or cooking). They must first investigate structural issues, insulation, and ventilation before suggesting that tenant behaviour is the cause.

However, responsibility does not sit with one party alone. Awaab’s Law reinforces a more balanced approach:

Landlord responsibilities:

• Investigate reported damp and mould within the required timeframes
• Identify and address structural issues, leaks, insulation, and ventilation
• Ensure the property is safe, warm, and suitable for occupation

Tenant responsibilities:

• Report damp and mould issues as early as possible
• Use ventilation systems, such as extractor fans, where available
• Take reasonable steps to manage moisture, such as avoiding excessive indoor drying where possible

In practice, mould in the home is often the result of a combination of environmental conditions and day-to-day living. The key shift is that landlords must now take the lead in identifying and resolving the root cause, rather than relying on surface-level explanations.

Note: While Awaab’s Law currently applies to social housing, the government is moving to extend these same protections to the private rented sector through the Renters’ Rights Bill.

What Causes Black Mould in the Home?

Having black mould in the home is a serious concern, so understanding what causes black mould is a key step in stopping it from becoming an issue. One of the main drivers of black mould growth is excess moisture in the home, which is why bathrooms are often hotspots. Condensation is a major trigger when warm air meets cold surfaces, so poor heating that creates cold spots, combined with poor ventilation and reduced airflow, can be a real issue.

Another common cause of black mould is leaks in the home, which create excess moisture. It is important to check pipes, roofs, and windows for any signs of leaks. Persistent damp is also a key indicator, as it is strongly linked to mould growth and fungus on walls.

Black mould anywhere in your home is a concern, but the room you spend the most time in should be a primary focus. This is why mould in the bedroom is so common:

• Breathing overnight increases the humidity in the room
• Having windows closed for long periods and poor ventilation can be a trigger
• Bedrooms have plenty of furniture blocking airflow

Symptoms of Black Mould Exposure

Exposure to black mould can be harmful, and it often affects respiratory health first. Understanding the symptoms of black mould is essential, especially when identifying early warning signs.

Short-term symptoms:

• Sneezing, coughing, and nasal congestion
• Irritated eyes, throat, and skin
  Headaches and fatigue

More serious symptoms:

• Breathing difficulties
• Worsening asthma
• Chest tightness

These symptoms of black mould poisoning and symptoms of black mould toxicity should never be ignored, particularly for those most at risk, including children, elderly individuals, and people with asthma or weakened immune systems. These are also commonly referred to as symptoms of mould sickness.

But can black mould kill you?

The risk of this is extremely rare and difficult to track, as causes are often recorded as respiratory failure or asthma rather than direct poisoning. However, the risk increases with prolonged exposure, particularly for vulnerable individuals.

Black Mould Effects on Health Over Time

Any exposure to black mould can create health issues, but long-term exposure can come with a Exposure to black mould can cause health issues, but long-term exposure can lead to more serious conditions, including:

• Chronic respiratory conditions
• Increased allergy sensitivity
• Ongoing fatigue and irritation

These black mould effects can worsen over time, particularly in damp homes where repeated exposure occurs. This can significantly impact overall well-being and quality of life.

Black Mould in Bedrooms: Why It’s a Concern

Black mould in the bedroom is particularly concerning as it leads to prolonged exposure during sleep. Mould on walls in the bedroom is often hidden behind wardrobes, beds, and curtains.

Bedrooms often have poor air circulation, as windows remain closed for long periods. This makes it easier for black mould in the home to develop unnoticed. Detecting early signs of mould in bedrooms and living spaces is essential, as these are areas where occupants spend the most time.

One of the more dangerous aspects of having black mould in the home is that it can often go unnoticed until it’s clearly visible or symptoms of black mould appear, especially with an estimated 962,000 to 6.5 million homes experiencing damp or mould issues.

How to Stop Mould in the House

The best way to manage black mould is by stopping it in its tracks. Knowing how to stop mould in the house early is key to protecting both your home and your health.

Everyday actions:

• Open windows regularly
• Use extractor fans
• Avoid drying clothes indoors where possible
• Keep furniture slightly away from walls

Environmental control:

• If possible, maintain a consistent indoor temperature
• Reduce humidity levels
• Use dehumidifiers where needed

Property maintenance:

• Fix leaks promptly
• Check insulation and ventilation systems

Landlords:

• There is a responsibility to address structural damp
• Supporting tenants with guidance and tools, and ensuring the home is managed well, and black mould doesn’t occur.
• Monitoring humidity and temperature is vital to identifying risk before mould appears

When to Seek Professional or Medical Advice

Black mould in the home can pose serious risks, and action should be taken if:

• Mould keeps returning after cleaning
• Large patches of black mould are visible
• Symptoms of black mould persist or worsen

Tenants should report issues to landlords as early as possible. Landlords should investigate the root cause rather than only treating surface-level mould. Having access to humidity and environmental data can help prevent recurring issues.

It is important to seek medical advice if symptoms of black mould occur, persist or worsen; ongoing respiratory symptoms are a big red flag. There are plenty of triggers, and common signs that should be looked at are chronic coughing, wheezing, nasal congestion, watery/red eyes, skin rashes, headaches and fatigue.

If you are in any doubt, contact your GP or call 111 for medical advice.

Prevention Is Better Than Cure: How Monitoring Helps

ResiSure supports a proactive approach to tackling black mould, using accurate environmental data that highlights risk before it escalates. By turning hidden conditions into actionable insight, it becomes possible to prevent black mould, rather than simply respond to it.

Black mould isn’t just a surface issue; it is a sign of underlying environmental conditions that impact both the property and occupant health over time. Understanding the symptoms of black mould is only one part of the solution. The real value lies in identifying the conditions that allow it to develop and addressing them before visible mould or symptoms of mould sickness appear.

A reactive approach often means problems are only dealt with once damage has already occurred.

By contrast, continuous monitoring of humidity, temperature, and air quality provides clear, real-time insight into the conditions that lead to black mould in the home. This allows landlords and property managers to take early, targeted action, reducing the risk of recurring damp and disrepair, while protecting tenants and avoiding costly repairs.