Symptoms Of Mould Exposure

Moulds are microscopic fungi that exist all throughout our environment, both in the natural world and in our homes and buildings. 

Moulds spread by releasing spores. This isn’t always harmful, but high levels definitely can be.

Read on to find out all you need to know about mould exposure, and how it can make you ill.

What is mould illness?

Mould illness can happen when you are exposed to substances called ‘mycotoxins.’

The World Health Organisation’s definition of mycotoxins is “naturally occurring toxins produced by certain moulds (fungi) [that] can be found in food. The moulds grow on a variety of different crops and foodstuffs including cereals, nuts, spices, dried fruits, apples and coffee beans, often under warm and humid conditions”.

Mould in your home

According to Great Plains Laboratory, a US-based lab that created one of the first mycotoxin tests, you’re most likely to find mould on or in:

  • Window sills and doors
  • Plumbing
  • Bathrooms
  • Closets
  • Fireplaces and chimneys
  • Laundry rooms
  • Basements
  • Air conditioning systems
  • Roofs
  • Refrigerators

Mould in your body

Mould can have a number of effects on your body and your health.

All these symptoms fall under one of two categories (or you may have a combination of both): mould toxicity and mould allergy.

Mould is a common cause of allergies and asthma.1 If you’re allergic to mould spores, when you breathe them in (microscopic particles that float in the air), your immune system responds with symptoms that usually affect your sinuses and lungs, like coughing, stuffiness and sneezing.

Mould toxicity is primarily caused by mycotoxins, which are the poisons that the mould spores produce. Usually, the more mycotoxins you’re exposed to, the worse your symptoms. There are hundreds of mould toxins, and they each have many possible effects.2

Mould is a complicated topic because we don’t know enough about it yet to make many conclusions. We do know that mycotoxins have a negative effect on human health.³ 

Right now, we don’t know exactly how they play a role in the many diseases research has linked them to, and we don’t know how much of a problem they are.

Current research has shown that mould can affect almost any system in the body, and even appears to contribute towards the development of some cancers.⁴

Get personalised advice and support from one of our practitioners.

Book a consultation

Symptoms caused by mould

Here are some of the most common symptoms of mould toxicity cited in research studies, or reported by our practitioners here at Healthpath:

General symptoms:

  • insomnia
  • fatigue
  • hair loss
  • weight gain or loss
  • sweet cravings
  • light sensitivity
  • poor depth perception
  • memory loss
  • intolerance of fragrances and chemicals
  • nose bleeds

Neurological symptoms:

  • ‘stabbing’ headaches
  • brain fog
  • numbness
  • tingling
  • weakness
  • tremor
  • nerve pain
  • dizziness
  • musculoskeletal symptoms
  • joint and muscle pain
  • muscle cramps
  • general weakness
  • tics
  • muscle twitches

Psychiatric symptoms

  • anxiety
  • depression
  • OCD
  • irritability
  • skin symptoms
  • rashes and pruritus (itching)
  • immune system symptoms
  • recurrent infections
  • autoimmunity

Neurological symptoms of mould exposure

A 2020 study⁵ confirmed that some people affected by mould illness experience significant neurological problems. For example: 

  • Brain inflammation in the hippocampus (the area of the brain that governs memory, learning, and the sleep-wake cycle)
  • Decreased neurogenesis (the formation of new brain cells)
  • Impaired memory
  • Increased sensitivity to pain
  • Increased anxiety

The study also found that you don’t need to be exposed to whole mould spores to suffer mould reactions and mould illness. The mycotoxins the spores give off are so small that they can pass through almost any material. Mycotoxins appear to be the trigger in most mould illnesses.

In a nutshell, the researchers in this study found that the participants’ immune systems changed as a result of mould exposure. Those changes led to the above symptoms in their brains and their bodies.

They concluded that mould causes symptoms and illness through its ability to cause inflammation (your body’s response to something it ‘thinks’ is harmful).

How do you know if mould is making you sick?

It’s difficult to be sure that mould is responsible for your symptoms.

Mould-related illnesses are still controversial. A big reason for that is the lack of reliable testing. 

Things are getting better though: a few years ago, the only test for mould measured your levels of antibodies to it. That only helps to shed light on mould allergies, not mould toxicity. Today, we can test for some (not all) mycotoxins in urine.

If a mycotoxin urine test is positive, a good practitioner will start to tackle the specific mould involved. But if the mycotoxin test is negative, it doesn’t mean that mould definitely isn’t causing your symptoms, because there are hundreds of different mycotoxins, and no test measures all yet. 

You can read more about the dangers of mould in our blog post ‘Is mould dangerous?’.

How much mould exposure is harmful?

Everyone is different. You might be able to withstand a lot more mould exposure before getting sick than your friend, or even your sibling. 

Genetics, nutritional deficiencies, your ability to detoxify, your age and stress levels are all factors that can impact how fast you get sick from mould.

A group of people can all live in the same building with a mould problem and get completely different symptoms. Some of them may not get ill at all.

People with imbalanced, weak or underdeveloped immune systems, will suffer more from exposure to any kind of toxins. But even the healthiest person will eventually start to show symptoms after consistent and prolonged exposure to mould.

Warning signs of mould toxicity

We outlined the symptoms of mould toxicity above, but there may be warning signs that mould is affecting your house or your health before the problem becomes more obvious.

These signs suggest you could have mould in your home:

  • Allergic symptoms (especially in winter, when allergies are less symptomatic)
  • A damp or musty odour in one or more places
  • Frequent headaches
  • Difficulties breathing
  • The air in your home feels different
  • Your house has been flooded or currently has leaks

How long does it take to get sick from mould exposure?

It depends. If you’ve only been exposed once, you’re unlikely to get sick from mould, unless you have a sensitivity. Some people appear to be quite ‘immune’ from its effects and can take a lot of exposure before they get ill.

Let’s look at some factors that affect how quickly you’re likely to notice symptoms.

Allergies and sensitivities

If you have a mould allergy, your body ‘overreacts’ when it senses mould and desperately tries to rid itself of it. This is what’s called an inflammatory response, and usually means you get stuffy, sneezy and wheezy.

Amount of mould

Large amounts of mould are more likely to make you more ill, more quickly. 

Even a small amount can quickly trigger symptoms if you’re allergic to mould.

Duration of exposure

The longer you’re exposed to mould, the more spores you will inhale. The more spores you inhale (or take in through food or through your skin) the more likely you are to get ill.

Proximity to mould

How close are you to the mould? Proximity increases your exposure.

If you directly handle mould, you’re more likely to get symptoms. So if you clean or touch mouldy items, you’re more likely to get sick than someone who doesn’t.

Key takeaways

  • Moulds are everywhere in our environment and always have been. It’s only when they get out of control that they can become hazardous to human health.
  • Our homes are ideal breeding grounds for mould, especially if they are humid.
  • Mould can also exist inside your body, and there’s mounting evidence that it can cause disease for some people.
  • It’s difficult to know whether or not mould is responsible for your symptoms, because we don’t have perfect tests yet.
  • Work with an experienced practitioner to determine if mould is likely to be responsible for your symptoms.


Alexandra Falconer BA (Hons) DipCNM mBANT is a Registered Nutritional Therapist specialising in IBS and related conditions. A graduate of Brighton’s College of Naturopathic Medicine, she is committed to fighting the root causes of chronic illness and bringing functional medicine to everyone who needs it.

Before her natural health career, Alex was a journalist and copywriter. She continues to write for magazines and media agencies, and now combines her two great passions – writing and health – by creating content that empowers people to claim their right to a healthy body and mind.









Other articles you might like