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Mould toxicity, sometimes referred to as ‘sick building syndrome’, is a commonly unrecognised cause of chronic illness and can be a reason for unexplained anxiety along with fatigue, lack of ability to think clearly and gut dysfunction.


Symptoms of mould toxicity can be diverse  (1)  and far more common than realised in the UK where the damp conditions for much of the year can result in an environment in which mould spores can flourish.  If you suffer from a number of the following symptoms and perhaps have been to various doctors without a satisfactory answer, mould toxicity is worth considering:

  • unexplained anxiety.
  • loss of cognitive function and brain fog.
  • repeated upper respiratory infections such as repeat chest infections, asthma or chronic sinus infections.
  • symptoms that improve when you go away from your home to a less damp environment for a couple of weeks.
  • hormonal imbalances for which a root cause has not been found.
  • metabolic disorders so, for example, sensitivity to carbohydrates or lack of ability to absorb fats.
  • recurrent/systemic candida/thrush.
  • unexplained fatigue (diagnosed with chronic fatigue, ME or simply unexplained lack of energy) and weakness.
  • muscle aches, cramps, unusual pain – particularly ice pick type pains.
  • headaches and migraines.
  • recurrent infections and illnesses that can be hard to throw off.
  • multiple chemical sensitivities – including light, sound, perfumes and food.
  • tearing and blurred vision.
  • air hunger and temperature dysregulation.

Many of these symptoms can be due to other root causes but reactivity to mould toxins should be assessed and ruled out, particularly if the symptoms have persevered for some time with no explanation found despite multitudes of tests and investigations. It is also important to realise that you do not have to have signs of visible mould in your house to be suffering from mould toxicity although clear black mould (such as may be seen in the bathroom or kitchen), a house that has been flooded or older houses with attics and cellars are common breeding grounds for the biotoxins.

Mold in ceiling

So what is mould toxicity?

Moulds are fungi that grow best in warm, damp and humid conditions and has been described by the World Health Organisation in 2009 which can be read here.   As well as in buildings, mould can grow on food such as a variety of different crops, such as corn and various cereals, nuts, spices, dried fruits, apples and coffee beans.

A toxin is quite simply a poison and toxicity to mould is the inability in genetically susceptible individuals to process the toxins (known as mycotoxins which when toxic become known as bio-toxins) produced from a variety of mould species which can then lead to a series of biochemical alterations within the body and a complex downstream series of health consequences, which longer term can be quite detrimental.   Bio-toxins are known to be toxic to nerves, the skin, liver, gut and kidneys which explains some of the diverse effects that can be seen.

Mould toxicity can profoundly weaken the immune system which then can leave an individual more vulnerable to other opportunistic infections and viruses – such as Epstein Bar Virus and HSV which can lie dormant in the body, and of course COVID-19.  Due to its impact on the gut, nutritional deficiencies are common and create vicious cycles of imbalances from which it can be hard to escape.

Testing: if mould toxicity is suspected, testing for levels of mycotoxins in the body is the first step and can be done easily in the UK via a urine mycotoxin test (3) from Great Plains Laboratory which a registered healthcare practitioner can arrange for you at reasonable cost.

Nutrient Testing – there are a couple of very comprehensive panels that can be used to assess nutrient status of which functional blood chemistry testing is one of them.   Along with potential malabsorption of nutrients due to a damaged gut lining, biotoxins have been shown to inhibit the production of glutathione, one of the body’s major anti-oxidants – thus assessment of the various detoxification pathways can be helpful as this is also how the mould toxins need to be removed from the body.

Other conditions that may co-exist as a result may also needed to be tested for but this will depend on your history and symptoms.  Mould damages the gut lining and creates an environment that allows dysbiosis to develop and potential pathogenic bacteria to take-hold.  Candida overgrowth and certain other elements of dysbiosis will also be able to be assessed via the Great Plains urine test.  Suspected or known autoimmunity should also be considered along with other active viruses and infections that may be have been triggered by an altered immune function.

Testing your environment is not cheap so investigate your options carefully before you proceed.   Steps to take short term and which can help alleviate symptoms are improving indoor air quality and controlling air moisture levels (air filters used need to have a Hepa filter attached due to the particle size of the mould spores).   Common areas of growth in buildings other than in attics and cellars are window sills and doors, bathrooms, fireplaces and chimneys, laundry rooms, air conditioning system, roofs and refrigerators.   You can read more on Home Remediation here.

As I mentioned above, genetics play a role which is why some people can live happily in a mouldy environment without any apparent effect whilst others suffer.  Genetic testing is something to consider if you want to explore your genetic predisposition and which pathways may need extra attention.

An at home VCS (Visual Contrast Sensitivity) Test  – whilst not diagnostic, this at home test developed by Richie Shoemaker is based is a measure of one of the neurologic functions of vision called contrast which can help guide if further investigation may be warranted.

If you want to find out more about running any tests or help with recovering from potential mould toxicty or other condition please contact Katherine here.