Is mould your silent, toxic housemate?

Talia, a young woman in her mid-20s, moved to Hong Kong from Singapore for work. Over the course of a few months, she started to notice rashes – red patches of dry skin on her chest and the backs of her knees. She’d also developed a perpetual runny nose.

When Talia lived in Singapore, she was healthy and active, attending exercise classes several times a week. Since moving to Hong Kong, she was too exhausted after work to do anything besides cook dinner, watch TV and go to bed.

Sure something was wrong, she came to see Naturopathic doctor, Benita Perch. She told Benita that her ‘life felt small,’ but she didn’t feel able to make any changes – she was anxious, and reserved her energy for her job, where it was already a struggle to concentrate.

On top of this, her PMS had intensified. She and her partner noted that her mood swings during the luteal phase of her cycle had escalated – she was often teary, or snappy, and was prone to intense headaches in the days preceding her period.

Dr Benita asked if she’d noticed any mould at home – or if there were any funny smells. Talia confirmed that she made the arrangements for her new flat without ever seeing it, and when she arrived, she noticed there was an odd, musty smell in her bathroom – though nothing was visibly wrong.

Benita asked if there were times when Talia’s runny nose went away. Talia told her that when she returned to Singapore as a bridesmaid for a friend’s wedding, she remembered being relieved that her nose had stopped running after a few days in Singapore.

Her symptoms combined with the smell indicated to Benita that mould was the likely culprit.

“If your nose runs when you’re staying at home, but gets better when you leave – you likely have a mould problem,” says Dr Benita.

Why is mould dangerous?

Among Hong Kong patients, Dr Benita finds that Aspergillus and Penicillium are the most common mould species wreaking havoc with peoples’ health.

Mould species produce poisonous compounds called mycotoxins. They’re absorbed by the body via inhalation, touch or the consumption of contaminated foods  - often found in grains, nuts, animal products and vegetables. It’s estimated that 25% of the world’s food is contaminated with mycotoxins.

“Mould produces symptoms that you wouldn’t expect. Health conscious patients may be aware of some of the symptoms, like itchy skin, a blocked or runny nose, and fatigue, but mould affects much more – your hormones, mental health, cognitive function, and your immune response. In some instances, it’s the cause of autoimmune conditions,” says Dr Benita.

“Mould is so misunderstood – it’s considered to be a cosmetic issue, but it has long-term effects on your memory and heart health, causing chronic illness,” she adds.

Aspergillus produces some of the most commonly known mycotoxins: aflatoxins (which are a group 1 carcinogen, alongside the likes of tobacco), gliotoxins, patulin, ochratoxin A and citrinin. Penicillium produces ochratoxin A, patulin and citrinin.

Benita referred Talia for a MycoTOX profile – a urine test which assesses for 11 different mycotoxins, including aflatoxin M1, ochratoxin A, citrinin and gliotoxin.

Benita also ordered a blood test to check Talia’s nutrient levels, which can be affected by mould.

The test results confirmed Benita’s diagnosis - Talia had high levels of ochratoxin A (OTA) and citrinin (CIT), which are released by both Aspergillus and Penicillium mould species.

Ochratoxin A: hiding in your floors and heating ducts

Ochratoxin A is classed as a carcinogen and named by scientists as ‘among the most harmful common mycotoxins.’ It primarily targets the kidneys, but can cause multi organ toxicity.

One of the most common sources is water-damaged buildings, a feature which defines many of the older, high rise residential buildings in Hong Kong. Its favourite place to hide is in floors, carpet, ceiling tiles and heating ducts.

OTA is hard for your body to process and remove. It binds to a protein in your blood called albumin, and because our bodies require a certain amount of albumin to function, your body can’t excrete all the OTA from your body at once. It has to be filtered out of the body slowly.

The fatigue Talia was presenting with is a typical symptom of OTA. This mycotoxin causes low levels of albumin, as well as reduced zinc stores in cells, both of which result in fatigue. Talia’s blood tests confirmed she had low levels of zinc.

Talia was also low in B12, vitamin D and magnesium –nutrients commonly affected by mould exposure. Mould blocks vitamin D receptors, making it difficult to absorb. It can also affect your levels of vitamin C, vitamin E and selenium.

OTA is known to cause the other symptoms Talia was experiencing – struggling to exercise, headaches, itchy skin and brain fog.

It’s known that fungal VOCs (volatile organic compounds) also cause headaches, brain fog and inability to focus. Aspergillus, which produces OTA and citrinin, is one of the main culprits for producing VOCs.

Alongside these symptoms, OTA can also cause low appetite, nausea, chest pain, high blood pressure and muscle weakness or cramping.

OTA has a significant effect on your immunity. It suppresses the production of antibodies and prevents white blood cells from removing pathogens from the body. Its impact on your gut lining and oxidative stress also adds to the damage to your immune function.

Is citrinin living in your walls?

Often found alongside OTA, citrinin is also found in water-damaged buildings, as well as poorly stored grains. It tends to reside in wallpaper, wood, drywall, linoleum and insulation paper.

Citrinin attacks the kidneys, as well as causing mitochondrial dysfunction which affect the heart, digestion and hormones. Citrinin’s ability to affect your hormones was leading to Talia’s increased symptoms of PMS.

As the powerhouse of the cell, mitochondrial dysfunction causes chronic fatigue, muscle weakness, and an inability to exercise – all symptoms familiar to Talia.

This mycotoxin can also cause severe damage to the intestinal lining, leading to food sensitivities, reflux, nausea, diarrhoea and vomiting.

Other symptoms to look out for related to citrinin include blood sugar reactivity, shortness of breath and chest pain.

Citrinin affects the spleen and thymus – two organs essential for immune function. Its severe impact on the gut lining leads to leaky gut and dysbiosis, leaving your immunity vulnerable.

How to evict mould

If you’ve pulled a loved item from your wardrobe and found it covered in mould, you’re not alone.

“Hong Kong is a hotbed for mould because our environment is the perfect breeding ground. We’re subject to intense humidity, and because of pollution, don’t tend to open our windows much. Warm, poorly ventilated spaces, with a lack of sunlight due to surrounding high-rises provide a dark, damp, cosy environment for mould to thrive,” says Dr Benita Perch.

You might think that if you can’t see mould that you’re safe, but mould grows insidiously – invisible between the walls of our buildings or underneath our floors.

While some Hong Kong residents are aware of the health risks that mould poses –advice on Reddit shows many commenters suggesting that mould is ‘normal’ in Hong Kong, and recommending bleach as the solution.

“Bleach should not be used to combat mould – it might get rid of the cosmetic appearance, but it can feed it, as household bleach is usually over 90% water, causing the mould to come back with a vengeance, especially when applied to a porous surface,” warns Benita.

“If you can see the mould, it means it’s particularly bad. White vinegar blended with clove, tea tree and rosemary essential oils helps kill mould,” she adds.

A 2018 study applied antifungals, including clove oil and bleach to individual petri dishes of mould (including Aspergillus and Penicillium among others) assessing their efficacy over the course of 7 days. Not only did clove essential oil have a more powerful initial effect than bleach – it had sustained its antifungal power over the course of the full week. On the other hand, the efficacy of bleach decreased dramatically after day 3.

Benita also recommends airing out your flat on low pollution days and regular cleaning. Putting the heating on can also help dry up mould, and sunlight helps kill it – that’s why laundry was always traditionally dried outside.

Talia’s treatment

Dr Benita personalised a systemic detox programme for Talia, designed to improve her hormonal balance, relieve her fatigue and improve her mental health.

Part of Talia’s treatment plan was a dietary regimen rich in bioflavonoids. OTA is unbound from albumin by bioflavonoids, natural antioxidants found in plants like berries, kale, citrus, broccoli and onions. Benita recommended she flavour food with rosemary – an antifungal herb with a potent protective effect against OTA.

“Treating mould involves several steps. First we detox the body, then rebuild organ and mitochondrial health, focusing on the liver and kidneys, which are the primary organs affected by mould. And – we also have to kill the mould that’s hiding at home. Sometimes, that involves moving house. If that’s not currently possible, heavy duty air purifiers and dehumidifiers are key.”

Dr Benita recommended that Talia buy dehumidifiers for her bathroom, bedroom, and lounge, alongside air purifiers for her bedroom and lounge.

Within 6 weeks, Talia noticed a significant difference – but it wasn’t until she moved that her symptoms ceased.

If you’re living in a flat affected by mould, identifying a new location without the same problem can feel like a minefield. The Johnson group in Hong Kong can identify spores of mould in the air, but these tests aren’t always 100% reliable.

“You can use a moisture meter to identify where mould is – whether it’s in the wall cavity, or underneath the floorboards,” says Benita. “Also – trust your instincts. If the flat has a funny smell, avoid moving there. Your senses are intelligent,” she adds.

In summary

Mould releases chemical compounds called mycotoxins which are hugely damaging to our health. The two most common types in Hong Kong, Aspergillus and Penicillium, are found in the warm, damp, dark environment of many of our buildings.

Unexplained, or unresolved symptoms shouldn’t simply be endured. Our practitioners are committed to finding their cause. “When other treatments have been tried, with no results, often mould is the underlying cause,” says Dr Benita.

Our naturopathic doctors rule out other possible causes and refer you for tests to confirm a diagnosis.

They’ll then personalise a treatment plan to detox the mycotoxins from your body and rebuild organ health, plus give you practical advice on living in an apartment touched by mould.

References 
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Dr Jill Crista, Fact Sheet: Citrinin, 2021
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H Zeng et al, Endoplasmic reticulum stress promotes oxidative stress: a novel mechanism of citrinin – induces thymus and spleen injury, 2025.
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