Mould exposure symptoms: is mould making you ill?

Mould in a damp or water-damaged building most often causes airway, eye and skin symptoms. Typical ones are a blocked or runny nose, cough, wheezing, a sore throat, itchy eyes and rashes.

Some people develop a broader picture. They have fatigue, brain fog, headaches, aches and pains and symptoms in several body systems at once. Doctors who use the chronic inflammatory response syndrome (CIRS) model look for exactly this multi-system picture.

In both cases, the most useful clue is the same. Your symptoms follow the building: they get worse when you spend time there and ease when you are away.

This article explains the two kinds of symptom picture and how to link symptoms to a building. It also explains what “mycotoxins” mean for you, and which tests exist and where their limits are.

What are the symptoms of mould exposure?

Well studied The best-studied effects of damp and mould are on the airways. A large review looked at studies of whole populations (epidemiological studies). Visible dampness or mould indoors was consistently linked with [1]:

• asthma: new asthma and worsening of existing asthma
• shortness of breath, wheeze and cough
• respiratory infections and bronchitis
• allergic rhinitis (hay-fever-like symptoms in the nose) and eczema
• upper airway symptoms

The links were found in people with and without allergies [1]. The World Health Organization (WHO) reached a similar conclusion in its indoor air guidelines on dampness and mould [2]. A later review of systematic reviews judged the evidence strong enough to call mould a cause of asthma in children. It also found a link with allergic rhinitis [3].

Can mould cause fatigue and brain fog?

Preliminary research Beyond the airways, the evidence is thinner, but people report much more. A Finnish study looked at nurses and midwives working in a water-damaged hospital. They reported fatigue, “brain fog”, neurological symptoms, palpitations and musculoskeletal pain far more often than an unexposed comparison group. For example, 62 in 100 reported brain fog, against 11 in 100 in the comparison group [4]. The study was a questionnaire survey, so it shows an association, not a cause. Brain fog means that thinking feels slow and cloudy.

Dr Ritchie Shoemaker’s group describes patients from water-damaged buildings who had on average more than 20 symptoms across many organ systems [5]. These were clinical case series: reports that describe a group of patients. The group’s diagnostic consensus statement lists 37 symptoms, sorted into 13 clusters, which a doctor records in the medical history [6].

Allergic reactions or a multi-system picture?

Commonly reported symptoms fall into two groups [1][4][6]:

	Allergic and irritant reactions	Multi-system picture (may fit CIRS)
Typical symptoms	Blocked or runny nose, sneezing, cough, wheeze, shortness of breath, itchy eyes, rashes	Fatigue, brain fog, memory and word-finding problems, headaches, muscle and joint pain, light sensitivity, numbness or tingling, static shocks, frequent urination, temperature regulation problems, plus airway symptoms
Body systems involved	Mainly airways, eyes and skin	Several at once: nervous system, muscles, gut, airways, hormones
Timing	Often soon after entering the building	Usually develops gradually; may not settle quickly after leaving
Who is affected	People with allergies or asthma react most clearly, but symptoms also occur in people without allergies	Varies greatly; often not everyone in the same building
Main tests	Allergy tests (skin prick, specific IgE), lung function	Visual contrast sensitivity (VCS) test and the blood markers of the CIRS diagnostic process
Strength of evidence	Strong for airway effects	Limited and debated; much of it from one research group

The two pictures can overlap. Many people with a multi-system illness also have airway symptoms. And many people who only have a stuffy nose never develop anything more.

Is it a mould allergy, or could it be CIRS?

A mould allergy is an immune reaction to specific mould proteins. Doctors diagnose it with allergy tests and treat it like other allergies. Damp air can also irritate the airways, eyes and skin without any allergy.

CIRS is described as something different. It is an ongoing inflammatory reaction of the innate immune system, the body’s fast first line of defence. It follows exposure to the indoor air of water-damaged buildings and affects many organ systems at the same time [7].

In the CIRS model, the problem is not one toxin but the whole mixture found in damp buildings [5][8]:

• mould spores and fragments
• mycotoxins, toxins made by moulds
• bacteria and endotoxins, parts of the cell walls of certain bacteria
• microbial volatile compounds, gases released by microbes

Which signs point more to the multi-system picture?

These signs point more towards the multi-system picture than towards a simple allergy:

• symptoms from at least four or five different body systems, not just the nose and lungs [5][9]
• cognitive symptoms (problems with thinking) such as brain fog, poor memory or difficulty finding words
• symptoms that started after moving into, or working in, a particular building
• allergy tests that are normal even though you clearly react to the building

None of these prove CIRS. Fatigue and brain fog have many causes, from thyroid disease and anaemia to sleep apnoea and depression. A doctor should look for those first.

The CIRS diagnostic process is built on exactly this idea. It combines your exposure history, multi-system symptoms and objective test results, and rules out other explanations.

How do symptoms relate to time spent in a building?

Timing is the single most useful thing you can observe yourself. Ask yourself these questions:

• Did it start with a building? Note when you moved in or changed workplace, or when a leak or renovation happened.
• Is it worse in one place? Symptoms that build up during the working day point to the workplace. Symptoms that are worst in the morning after a night in one bedroom point to that room.
• Does it ease when you are away? Many people first notice this on holiday. Note how quickly the improvement comes and how complete it is.
• Does it come back when you return? In a small study by Shoemaker’s group, people whose symptoms had improved with treatment fell ill again within one to seven days of going back into the water-damaged building [9].

One small study The authors themselves note the study’s limits. Exposure to specific agents was not measured. The participants were not randomly selected. And the study was not blinded: everyone knew who was going back into the building.

What are mycotoxins and can they cause symptoms?

Mycotoxins are toxic compounds made by some moulds. Most people meet them through food. Examples are deoxynivalenol in cereals and ochratoxin A in coffee, cereals and dried fruit.

Some moulds that grow in water-damaged buildings can also make mycotoxins. These can be present in indoor dust and air, together with many other microbial substances [5].

Do mycotoxins in a damp building make people ill?

This is one of the most debated questions in the field. The question is whether mycotoxins cause symptoms at the levels people actually breathe in.

• One view: A review of illness linked to water-damaged buildings describes several possible mechanisms. They include inflammation, oxidative stress (a kind of cell damage), toxicity, allergy and irritation [8].
• The other view: A critical review by allergy and immunology specialists argues that there is no scientific evidence that indoor mould causes memory loss, fatigue and headaches through “mycotoxicosis”, meaning mycotoxin poisoning [10].

The CIRS model sidesteps part of this argument. It treats the immune system’s response to the whole mixture, not a single toxin, as the cause of illness. For more, see biotoxins and CIRS.

Is there a test for mould exposure?

No single test shows that mould is making you ill. These tests exist:

• Allergy tests. Skin prick tests and specific IgE blood tests show whether you are allergic to particular moulds. IgE is the type of antibody involved in allergies. These tests are recommended when an allergy is suspected [11].
• Lung function tests if you cough, wheeze or are short of breath.
• Urine mycotoxin tests. These are sold directly to consumers and through some clinics. They are not a validated way to diagnose illness from a building. A review based on the German medical guideline on indoor mould says that blood or urine tests for mould components or their breakdown products are generally not needed in the medical evaluation [11]. A positive result also says little about the source. In a study in Germany, mycotoxins or their breakdown products were found in 87% of urine samples, so in almost 9 out of 10 people. They were mainly toxins known from cereal foods [12].
• The VCS test. The visual contrast sensitivity (VCS) test measures how well you see fine differences in shades of grey. Shoemaker’s group uses it as a screening test for CIRS. In their studies, VCS was abnormal in most patients from water-damaged buildings and improved with treatment [5][9]. A failed VCS test is not a diagnosis, and a passed one does not rule CIRS out.
• CIRS blood markers. Doctors who treat CIRS use a panel of blood tests, such as MSH, MMP-9, TGF-β1 and C4a, to look for the inflammatory pattern. These markers show inflammation, not exposure. One research group developed most of them.
• Building inspection. For the building itself, a qualified moisture and indoor air inspection tells you more than any single air or dust sample. See signs of water damage for what to look for.

Why does only one person in the family get ill?

Often one family member is very ill while others feel fine in the same home. Part of this is ordinary variation. People with asthma or allergies react more clearly, and sensitivity varies from person to person [1].

Expert opinion The CIRS model adds a genetic explanation. It proposes that certain immune response genes make it harder for some people to clear these substances. See genetic susceptibility to CIRS. This idea comes mainly from Shoemaker’s group, and independent studies have not confirmed it.

What should you do if you think mould is making you ill?

How strong is the evidence?

Well studied The link between damp and mouldy buildings and airway symptoms, asthma and allergic rhinitis is well established. The WHO accepts it [1][2][3].

Preliminary research The link to fatigue, brain fog and multi-system illness is much less certain. The evidence comes from:

• questionnaire studies [4]
• small uncontrolled studies and case series, mostly from Shoemaker’s group [5][9]
• reviews written by clinicians who treat CIRS [7][8]

Many allergists and environmental medicine specialists remain sceptical [10][11]. There is also no agreed test that proves building-related illness in an individual person.

Honest advice therefore combines both views. Take a clear link between your symptoms and a building seriously, and act on the building. At the same time, look for other causes with your doctor.

Remember these

Check yourself: Why does a positive urine mycotoxin test say little about your home? And which signs point more to a multi-system picture than to an allergy?

What next?

• Read what it means if your symptoms ease when you are away from home.
• See the full list of CIRS symptoms in 13 clusters, or count yours with the symptom checklist.
• Learn the signs of water damage in your home.

References

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2. World Health Organization. WHO guidelines for indoor air quality: dampness and mould. Copenhagen: WHO Regional Office for Europe; 2009. WHO
3. Caillaud D, Leynaert B, Keirsbulck M, Nadif R; mould ANSES working group. Indoor mould exposure, asthma and rhinitis: findings from systematic reviews and recent longitudinal studies. Eur Respir Rev. 2018;27(148):170137. PubMed
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8. Hope J. A review of the mechanism of injury and treatment approaches for illness resulting from exposure to water-damaged buildings, mold, and mycotoxins. ScientificWorldJournal. 2013;2013:767482. PubMed
9. Shoemaker RC, House DE. A time-series study of sick building syndrome: chronic, biotoxin-associated illness from exposure to water-damaged buildings. Neurotoxicol Teratol. 2005;27(1):29–46. PubMed
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