Mould in the Home: The Silent Threat to Your Brain, Body and Child's Development

My Experience with Mould Over the Years

Most of us have spotted a patch of mould at some point, perhaps in a steamy bathroom corner, creeping across a window frame, or blooming unexpectedly along a ceiling. Over the years, I’ve encountered black, green, and even red mould in places like bathrooms or quietly building up on ceilings near windows. At first glance, it might seem like a cosmetic issue, something unpleasant, but harmless. Just a bit of damp, right?

But mould is far more than an unsightly nuisance. Behind those discoloured patches may lie microscopic spores and toxic compounds capable of triggering a wide range of symptoms, especially in vulnerable groups like children. For many, the connection between mould and their mental or physical health isn’t immediately obvious. Instead, symptoms creep in slowly: brain fog, low mood, constant tiredness, or frequent colds, often brushed off or misdiagnosed.

In this article, we’ll explore how everyday mould, particularly the kind that builds up quietly in homes, can affect the brain, body, and a child’s development. We’ll also cover the types of mould you’re most likely to encounter indoors, how to spot the warning signs, and what to do if you suspect it’s affecting your health or your child’s wellbeing.

What Is Mould and Why Does It Grow Indoors?

Mould is a type of fungus that thrives in moist, humid conditions. It reproduces by releasing microscopic spores into the air, spores that can settle and grow anywhere there’s moisture, warmth, and a food source like wood, fabric, wallpaper glue, or even household dust.

In modern homes, mould often appears in areas with poor ventilation or where condensation regularly builds up, think bathrooms, kitchens, around windows, or behind furniture placed against cold walls. Leaky pipes, roof damage, or even drying laundry indoors can quietly create the perfect breeding ground.

The problem is especially common in homes that are sealed tightly for energy efficiency. While these measures help conserve heat, they also trap moisture inside, creating the ideal environment for mould to thrive. And unlike dirt or dust, mould doesn't just sit on the surface, it penetrates into materials and, in some cases, releases harmful compounds known as mycotoxins.

While a small patch might seem harmless, repeated or long-term exposure to indoor mould, particularly certain toxic strains, can pose a serious risk to health.

Common Types of Indoor Mould and Where They’re Found

Not all mould is created equal, different species have different appearances, health impacts, and favourite hiding places. Most indoor moulds range in colour from black to green, white, or even red, and each one can behave differently depending on the conditions of your home.

1. Stachybotrys chartarum (Black Mould)

Appearance: Thick, slimy, black or dark green.

Where it grows: Damp drywall, wallpaper, ceilings near windows, insulation, and under carpets.

Risks: Produces mycotoxins linked to neurological symptoms, respiratory issues, and immune disruption.

2. Aspergillus (Green or Yellow Mould)

Appearance: Powdery, green/yellow/white.

Where it grows: Dust, HVAC systems, damp walls.

Risks: Can produce aflatoxins, harmful to the liver and nervous system.

3. Penicillium (Green or Blue Mould)

Appearance: Velvety, blue or green.

Where it grows: Water-damaged furniture, walls, books.

Risks: Can trigger allergy symptoms like sneezing and sinus issues.

4. Cladosporium (Black or Olive Mould)

Appearance: Suede-like, olive or dark brown/black.

Where it grows: On fabrics, carpets, bathroom tiles.

Risks: Strong allergen; aggravates asthma and lung issues.

5. Alternaria (Dark Green or Brown Mould)

Appearance: Velvety with dark hues.

Where it grows: Around windows, showers, sinks.

Risks: Known asthma trigger and airborne allergen.

What About Red Mould?

If you've ever noticed reddish-pink mould in your bathroom, especially around shower seals or tiles, you’re likely looking at Serratia marcescens, a bacteria (not a true mould).

Where it grows: Damp bathroom areas, especially with soap residue and stagnant water.

Why it appears: Feeds on minerals and phosphates in tap water and personal care products.

Risks: Usually harmless to healthy individuals but can cause infections in those with weakened immunity.

If you’re seeing it frequently, consider filtering your shower water or improving ventilation and cleaning routines.

Mental and Neurological Effects of Mould Exposure

Certain moulds, particularly those that produce mycotoxins, can disrupt the nervous system, contribute to neuroinflammation, and alter brain chemistry. These effects can appear gradually and be mistaken for stress, burnout, or even depression.

How It Affects the Brain:

Neuroinflammation

Mitochondrial dysfunction (reduced cellular energy)

Disrupted neurotransmitters (e.g., serotonin, dopamine)

Oxidative stress

Symptoms Include:

Brain fog

Poor memory or concentration

Anxiety and panic attacks

Low mood or depression

Mood swings or irritability

Sleep disturbances

Sensitivity to light, noise, or smells

Some people describe it as “mental shutdown” or feeling like they’re walking around in a fog.

Physical Symptoms of Mould Exposure

Mould can affect multiple systems in the body, often causing vague or chronic symptoms that don’t respond to typical treatments.

Respiratory:

Chronic cough

Sinus congestion

Shortness of breath

Asthma flare-ups

Skin & Eyes:

Eczema or rashes

Hives

Red or itchy eyes

Digestive:

Bloating

Food sensitivities

Irregular bowel movements

Fatigue & Pain:

Chronic fatigue

Joint or muscle aches

Brain fog and exhaustion after small efforts

Hormonal & Immune:

Disrupted sleep-wake cycle

Hormonal imbalance

Recurrent infections

Feeling hot/cold for no reason

Mould Exposure and Its Effect on Children

Children are particularly vulnerable because their immune and nervous systems are still developing. What seems like “normal kid problems” can sometimes be environmental in nature.

Health Symptoms in Children:

Recurring coughs or colds

Skin flare-ups

Digestive complaints

Chronic fatigue

Developmental Effects:

Delayed speech or learning difficulties

Behavioural issues or tantrums

Anxiety or disrupted sleep

ADHD-like symptoms

Many of these symptoms improve when the child is away from home, yet mould is rarely considered.

Signs You Might Have a Mould Problem

Visible Signs:

Black or green spots on ceilings or walls

Discolouration or peeling paint

Pink or red slimy streaks (in bathrooms)

Smells:

Musty, earthy odour that lingers

Damp smell in cupboards, under stairs, or wardrobes

Environmental Triggers:

History of leaks or flooding

Condensation on windows

Poor ventilation in bathrooms or kitchens

Hidden Hotspots:

Behind wallpaper

Under carpets

Inside air vents

Behind furniture on external walls

Testing and Identifying Hidden Mould

When to Test:

Symptoms improve outside the home

A musty smell lingers

No visible mould, but high humidity or past water damage

Testing Options:

DIY kits: Basic, low-cost, not always reliable.

Professional assessment: Uses air sampling, surface testing, thermal imaging.

ERMI or HERTSMI-2: Lab tests that detect mould DNA in dust.

Urine mycotoxin testing: Checks for mould exposure in the body (via functional medicine labs).

For serious or chronic symptoms, combining home and health testing gives the clearest picture.

What to Do If You Suspect Mould

Don’t:

Dry scrub or use bleach on porous surfaces

Ignore your instincts, mould doesn’t always look dramatic

Do:

Use vinegar, clove oil, or hydrogen peroxide (with PPE) for small areas

Call professionals for larger areas or hidden mould

Fix leaks, improve airflow, reduce humidity

Use HEPA air filters and remove contaminated materials when necessary

Even small improvements, like better bathroom ventilation, can make a big difference.

Supporting Recovery After Mould Exposure

Once you’ve removed the source, it’s time to focus on healing your body and brain.

Detox Support:

Stay hydrated

Consider binders (e.g., activated charcoal) under professional guidance

Support liver detox with cruciferous vegetables, milk thistle, glutathione

Infrared sauna or Epsom salt baths

Nutrition:

Anti-inflammatory foods

Avoid sugar, processed foods

Probiotic-rich foods for gut repair

Nervous System & Mental Health:

Gentle breathwork

Hypnotherapy or meditation

Emotional support, especially for children

For Children:

Nutritious meals, rest, and a safe environment

Emotional reassurance

Observation for improvement in focus, behaviour, and energy

Conclusion

Mould in the home is more than just an eyesore, it can be a silent disruptor of mental clarity, physical health, and childhood development. For years, I brushed off those black spots in the bathroom or the musty smell near the window. I didn’t realise that something so common and so often dismissed, could have such a profound effect on the way we feel, think, and function.

Whether it shows up as brain fog, anxiety, digestive issues, or your child struggling with sleep or focus, the source may be closer than you think.

The good news? Once identified, mould can be dealt with. Homes can be remediated. Bodies can heal. And clarity, both mental and environmental, can return.

If any part of this article resonated with you, trust your instincts. Ask questions. Take a closer look at your environment. You don’t have to live with unexplained symptoms. Awareness is the first step toward recovery, for yourself, and for those you care about most.