Is Mould Making You Sick? Common Symptoms of Indoor Mould Exposure

Understanding the Health Effects of Indoor Mould in South East Queensland Homes

Mould is one of the most common indoor environmental problems affecting homes and buildings throughout South East Queensland. From Brisbane and Logan to Ipswich, Redlands, Moreton Bay and the Gold Coast, the region's warm temperatures, humidity and seasonal storms create ideal conditions for mould growth.

While many people think of mould as simply an unsightly stain on a wall or ceiling, the reality is that mould can have a much greater impact on a property and the people living inside it. One of the most common questions homeowners ask is:

"Is mould making me sick?"

The answer is not always straightforward.

Some people can live around mould with little or no noticeable symptoms, while others may experience significant irritation, allergic reactions or worsening respiratory issues. The effects can vary depending on the type and extent of mould growth, indoor air quality, individual sensitivities and existing health conditions.

In this guide, we'll explore the common symptoms associated with indoor mould exposure, how mould affects indoor air quality, why some people react more than others, and when it may be time to arrange a professional mould inspection.

What Is Indoor Mould?

Mould is a naturally occurring fungus that exists both indoors and outdoors. It reproduces by releasing microscopic spores into the air.

Outdoors, mould plays an important role in breaking down organic matter. Indoors, however, mould can become a problem when it grows on building materials, furniture, fabrics or contents due to excess moisture.

Mould commonly grows on:

• Plasterboard and drywall

• Painted walls and ceilings

• Timber framing

• Carpet and underlay

• Curtains and fabrics

• Furniture

• Insulation

• Ceiling cavities

• Air conditioning systems

• Roof spaces

• Bathroom surfaces

Mould growth occurs when moisture is present for an extended period. Common causes include:

• Roof leaks

• Plumbing leaks

• Water damage

• Flooding

• Poor ventilation

• High humidity

• Condensation

• Rising damp

• Building defects

Once mould begins growing indoors, spores can become airborne and spread throughout the property.

Why Indoor Mould Can Affect Health

The primary concern with indoor mould is not always the visible growth itself.

The bigger issue is often what cannot be seen.

As mould grows, it releases microscopic spores into the air. These spores can travel through rooms, air conditioning systems and ventilation pathways.

In some situations, mould may also release microbial volatile organic compounds (MVOCs), which are responsible for the characteristic musty smell commonly associated with mould-contaminated buildings.

When mould spores become airborne, occupants may inhale them during normal daily activities.

For some individuals, this can trigger symptoms ranging from mild irritation to more significant respiratory or allergic reactions.

The degree of reaction varies from person to person.

Why Some People Are More Sensitive to Mould Than Others

One of the most confusing aspects of mould exposure is that people often react differently.

In the same household:

• One person may experience symptoms every day.

• Another person may feel completely normal.

• Children may react differently to adults.

• People with asthma may experience stronger reactions.

• Individuals with allergies may be more sensitive.

Several factors influence how someone responds to indoor mould exposure:

Existing Allergies

People with environmental allergies may be more likely to react to airborne mould spores.

Asthma

Mould exposure can aggravate asthma symptoms in some individuals.

Age

Young children and older adults may be more sensitive to environmental irritants.

Immune System Function

Individuals with weakened immune systems may be more susceptible to environmental contaminants.

Duration of Exposure

Someone exposed to mould daily for months may experience different effects compared to someone exposed briefly.

Concentration of Mould

A small amount of mould in a bathroom corner may present a different exposure profile compared to widespread contamination behind walls and ceilings.

Common Symptoms of Indoor Mould Exposure

Although mould affects people differently, several symptoms are commonly reported in mould-affected environments.

It's important to note that these symptoms can have many possible causes and do not automatically mean mould is responsible.

However, if symptoms consistently improve when away from the property and worsen when at home, mould may be worth investigating.

Persistent Sneezing and Nasal Irritation

One of the most common complaints associated with mould exposure is ongoing irritation of the nose and upper respiratory system.

People may experience:

• Frequent sneezing

• Runny nose

• Nasal congestion

• Post-nasal drip

• Irritated sinuses

Many people assume they simply have seasonal allergies, but symptoms that persist year-round may indicate an indoor environmental trigger.

If symptoms seem worse inside the home than outside, mould or indoor air quality issues may be contributing factors.

Chronic Coughing

A persistent cough can sometimes be associated with poor indoor air quality.

People often describe:

• Dry coughing

• Irritating throat sensations

• Frequent throat clearing

• Coughing that worsens overnight

This can be particularly noticeable in bedrooms where mould may be hidden behind walls, ceilings or furniture.

Because people spend many hours sleeping in one room, exposure can be more prolonged.

Watery, Itchy or Irritated Eyes

Mould spores can irritate sensitive tissues, including the eyes.

Common symptoms include:

• Itchy eyes

• Red eyes

• Watery eyes

• Burning sensations

• Eye irritation that worsens indoors

These symptoms are often mistaken for hay fever or seasonal allergies.

Headaches That Seem Worse Indoors

Many people living in mould-affected environments report recurring headaches.

While headaches can have numerous causes, some individuals notice a pattern where symptoms:

• Worsen at home

• Improve when away

• Return after spending time indoors

If a property has a strong musty odour, moisture problems or visible mould growth, it may be worth investigating further.

Sinus Problems and Facial Pressure

Ongoing sinus irritation is commonly reported in damp and mould-affected buildings.

People may experience:

• Sinus congestion

• Facial pressure

• Blocked nasal passages

• Difficulty breathing through the nose

• Frequent sinus infections

Because mould spores are airborne, they may contribute to irritation of the upper respiratory tract in sensitive individuals.

Worsening Asthma Symptoms

For people who already have asthma, mould exposure may aggravate existing symptoms.

This can include:

• Increased wheezing

• Shortness of breath

• Chest tightness

• More frequent use of asthma medication

• Increased sensitivity to indoor environments

If asthma symptoms seem noticeably worse at home than elsewhere, a mould inspection may help identify whether moisture or mould issues are contributing.

Skin Irritation

Some people report skin irritation when exposed to mould-contaminated environments.

This may include:

• Itchy skin

• Mild rashes

• Skin redness

• General irritation

Again, symptoms vary significantly between individuals.

Fatigue and Feeling Run Down

One of the more difficult symptoms to evaluate is fatigue.

Many people living in damp or mould-affected environments report:

• Feeling unusually tired

• Lack of energy

• Difficulty concentrating

• Poor sleep quality

• Feeling run down

These symptoms can have numerous causes, but if they coincide with visible mould, musty odours or known water damage, it may be worthwhile investigating indoor environmental conditions.

Musty Smell But No Visible Mould

One of the biggest misconceptions about mould is that you should always be able to see it.

In reality, mould often grows in hidden locations such as:

• Wall cavities

• Ceiling cavities

• Roof spaces

• Under carpets

• Behind furniture

• Behind cabinetry

• Inside air conditioning systems

• Behind insulation

Sometimes the only clue is a persistent musty odour.

If your home smells damp or musty despite regular cleaning, hidden mould may be present.

This is one of the most common reasons people arrange professional mould inspections.

Signs Your Home May Have a Hidden Mould Problem

In addition to health-related concerns, there are often physical signs within the property itself.

Common indicators include:

Water Stains

Brown, yellow or discoloured staining on walls and ceilings often indicates past or ongoing moisture issues.

Bubbling Paint

Moisture trapped behind painted surfaces can cause paint to blister or peel.

Peeling Plaster

Water-damaged plasterboard may begin deteriorating.

Condensation

Persistent condensation on windows may indicate excessive indoor humidity.

Musty Odours

A strong musty smell is one of the most common indicators of hidden mould growth.

Previous Water Damage

If the property has experienced:

• Roof leaks

• Flooding

• Burst pipes

• Storm damage

there may be hidden moisture supporting mould growth.

Can Mould Grow Where You Can't See It?

Absolutely.

In fact, many significant mould issues begin in concealed areas.

Common hidden mould locations include:

• Behind walls

• Above ceilings

• Inside roof cavities

• Behind kitchen cabinetry

• Behind bathroom vanities

• Beneath flooring

• Under carpets

• Around window frames

• Inside air conditioning units

By the time mould becomes visible, contamination may already be much more extensive than initially thought.

This is why professional mould inspections often include:

• Moisture testing

• Thermal imaging

• Environmental assessment

• Building condition assessment

to identify issues that may not be visible during a normal walkthrough.

When Should You Arrange a Professional Mould Inspection?

You should consider a mould inspection if:

• You smell mould but can't find it

• Symptoms seem worse inside the home

• The property has experienced water damage

• Mould keeps returning after cleaning

• You notice unexplained staining or moisture

• You are purchasing a property

• You manage rental properties

• Tenants report mould concerns

• You suspect hidden mould behind walls or ceilings

A professional inspection helps identify:

• Whether mould is present

• Potential moisture sources

• Areas requiring further investigation

• Conditions contributing to mould growth

• Recommendations for remediation and prevention

Why Simply Cleaning Visible Mould May Not Solve the Problem

Many people attempt to remove mould themselves using supermarket cleaning products.

While surface cleaning may improve appearance temporarily, it often fails to address:

• Hidden mould growth

• Moisture sources

• Condensation problems

• Building defects

• Water ingress

• Elevated humidity

If the underlying moisture problem remains, mould often returns.

This is why professional inspections focus on identifying the cause, not just the visible symptoms.

Final Thoughts

Mould can affect both buildings and indoor air quality, and some individuals may experience symptoms such as sneezing, coughing, sinus irritation, itchy eyes or worsening asthma when exposed to mould-contaminated environments.

While symptoms vary significantly from person to person, recurring health concerns combined with musty odours, visible mould or moisture problems should not be ignored.

The most effective way to address a mould problem is to identify the source of moisture, assess the extent of contamination and implement appropriate remediation measures.

If you suspect hidden mould in your home, office, rental property or commercial building, a professional mould inspection can provide clarity and help determine the next steps.