Could mould in my house be making me sick?
One of my patients started sneezing almost as soon as she walked through her front door. Her asthma, which normally only showed up with exercise, began flaring at home, and she was reaching for her reliever inhaler far more than usual. We had the house inspected, and the timber under her bath turned out to be rotting. Once it was repaired, she noticed the difference every time she came home.
Mould sickness is hard to confirm from symptoms alone, because tiredness, headaches, aches and a blocked nose have many possible causes. The clearer clues usually sit in your house and in your patterns. Think water damage, other people at home feeling unwell, and symptoms that ease when you’re away. At Merge Health, that’s where we start.
That’s the thing about mould. The answer is often hiding somewhere you walk past every day.
Table of Contents
What clues in your house point to mould?
Water is the biggest clue. Mould needs moisture to grow, so any past or current water damage is worth taking seriously, even if you can’t see mould anywhere. When I suspect mould, the first thing I ask is whether there’s been a leak, a flood or any sign of water in the home.
Things worth noticing:
- A musty smell in a wardrobe, cupboard or room
- Condensation on windows that hangs around
- Water stains on ceilings or walls, or paint that’s bubbling
- Spots on a bathroom ceiling that keep coming back after cleaning
- An old leak under a sink, shower or bath
Why does it matter if others in your home are unwell?
Mould can affect people who share a space in quite different ways, so other people’s health is a clue too. When I suspect mould, I always ask whether anyone else in the home is unwell. One person might sneeze constantly while another feels exhausted or foggy. When a few people in one house are all a bit off, the house is worth a closer look.
What are the symptoms of mould sickness?
Mould illness symptoms can show up quickly or build slowly. The most common things people mention in clinic are fatigue, headaches, body aches and low mood. Breathing symptoms are the best researched. A 2007 meta-analysis in the journal Indoor Air linked damp and mouldy homes with roughly 30 to 50 per cent increases in a range of respiratory and asthma-related problems.
In my experience, mould in the house symptoms often follow this timing:
| When it shows up | What people often notice |
|---|---|
| Soon after walking in the door | Sneezing, coughing, asthma flaring, a runny or blocked nose |
| After a few days at home | Overwhelming fatigue, brain fog, body aches, headaches, itchy skin or eczema flares |
One of the more unexpected things people tell me about is static shocks. It sounds odd, but it comes up often enough that I always ask.
Why does mould sickness get mistaken for hay fever?
Mould sickness often looks like allergies, so it gets put down to the season. I hear “it’s just hay fever” a lot, even when it isn’t the season for it. If your sneezing, coughing or asthma doesn’t follow the pollen calendar, or gets worse at home and better elsewhere, that pattern is worth paying attention to.
The same goes for symptoms that “everyone has”. Being tired, achy and foggy is common, but common doesn’t mean it’s normal for you. Picking up more symptoms isn’t simply part of getting older, and it’s worth looking into.
What is CIRS?
Chronic inflammatory response syndrome (CIRS) is a term some practitioners use for long-standing inflammation in response to something in your environment, such as a water-damaged building. The way I explain it is that your body doesn’t switch off the reaction, so it just keeps going. CIRS is still debated, and it isn’t recognised as a diagnosis by all doctors. An Australian parliamentary inquiry looked at it in 2018 and called for more research.
What can you do this week?
Start by noticing patterns, because they tell you far more than any single symptom. A fortnight of notes about where you were and how you felt is often enough to show whether your bad days follow a place.
- Notice how you feel when you’re away from home for a few days, at work, with family or on holiday.
- Track your symptoms each day for two weeks, noting where you were and how you felt.
- Check your home for signs of water damage, and talk to a qualified building or mould inspector if you find any.
- Leave larger patches of mould for a professional rather than scrubbing them yourself, because disturbing it can spread spores.
- Spend as much time as you comfortably can away from any area you suspect.
- Take your notes to your GP, and keep them involved.
In our 14-Day Missing Link Pattern Map, this is the pattern we call The Hidden Load. Your bad days follow where you’ve been, not what you did.
What this doesn’t tell you
A pattern can point you towards mould, but it can’t confirm it. These symptoms overlap with many other things, so a pattern is a starting point for a conversation, never a diagnosis. At Merge Health, we often see environmental load like mould turn up alongside other conditions, such as mast cell activation syndrome (MCAS) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). That’s why we look at the whole picture, and it’s the focus of our work in mould illness at Merge Health.
Frequently asked questions
Can mould make you sick if you can’t see it?
Yes, it can. Mould often grows where you can’t see it, behind walls, under floors or beneath a bath. A musty smell or a past leak can be a more useful clue than anything visible. A qualified inspector can check areas you can’t reach.
Is this all in my head?
No. Feeling worse in one place and better in another is a real pattern worth taking seriously. Tracking it gives you something concrete to take to your GP or practitioner, rather than a vague feeling that something is off.
Why does only one person in my house feel unwell?
People can respond to the same environment in very different ways. One person might sneeze, another might feel exhausted, and someone else might notice nothing at all. One person feeling well doesn’t rule the house out.
Is CIRS the same as a mould allergy?
No. A mould allergy is a fast immune reaction, the kind that causes sneezing, itchy eyes or asthma soon after exposure, and allergy testing can often pick it up. CIRS describes a longer-running inflammatory response that doesn’t switch off, with symptoms like fatigue and brain fog. You can have one, both or neither.
When to see a doctor
Chest pain, fainting, new weakness or numbness, unintentional weight loss, blood in your stool, a sudden severe headache or a fever that won’t settle need a doctor, not an article. If your asthma is getting worse, keep following your asthma action plan and see your GP promptly. Keep your GP involved in any changes to your health.
Next step
If you’d like to see whether your bad days follow where you are, start with the 14-Day Missing Link Pattern Map. It takes two minutes a night, and by the end you’ll know whether place is doing a lot of the work.
About the author
Kate McCandless is a co-founding director of Merge Health, a naturopath and clinical nutritionist, and a certified mould assessor. She has more than 24 years in healthcare, with a clinical focus on mould illness, CIRS and chronic infection.
References
- Fisk WJ, Lei-Gomez Q, Mendell MJ. Meta-analyses of the associations of respiratory health effects with dampness and mold in homes. Indoor Air. 2007;17(4):284–96. doi.org/10.1111/j.1600-0668.2007.00475.x
- House of Representatives Standing Committee on Health, Aged Care and Sport. Report on the Inquiry into Biotoxin-related Illnesses in Australia. Parliament of Australia, October 2018. aph.gov.au
