Introduction

Chronic sinusitis is a common condition where the nasal passages and sinuses become inflamed and swollen for a period of 12 weeks or longer.¹ One common trigger for sinusitis is allergies.^3,4,5 When people who are sensitive to certain allergy-causing substances (known as allergens) are exposed to them, their immune system reacts.⁴ This causes symptoms like swelling and excess mucus in the nasal passages.⁴ Mould is a type of fungus that is found in damp environments and can be an allergen for some people.^6,7 For those affected, repeated or prolonged exposure to mould can lead to ongoing sinus inflammation and increase the risk of developing chronic sinusitis.^3,8

What is chronic sinusitis?

Sinusitis is a common condition where the nasal passages and sinuses of the face become inflamed and swollen.¹ It becomes known as chronic sinusitis when the inflammation persists for 12 weeks or longer. It is usually caused by exposure to germs or by substances that cause allergic reactions (known as allergens). The facial sinuses allow the air that we breathe in to be filtered for nasty substances, which are then drained away.² Long-lasting inflammation obstructs the nasal passages and sinuses, meaning that germs can colonise and grow. This puts pressure on the sinuses and causes symptoms like:^1,2

• A blocked or runny nose
• Green or yellow mucus from the nose
• Facial and/or dental pain
• A reduced sense of smell
• A high temperature
• Headaches
• Mouth breathing and bad breath

These symptoms mean that chronic sinusitis can be a very uncomfortable condition to live with.^1,2

Understanding mould and its allergies

Moulds are fungi that can grow inside and outside of the home. They come in many different species and release spores, which can become allergens. Mould spores have been associated with an increased risk of developing allergies.^3,4,5 This is more likely when mould has grown inside the home due to close and prolonged exposure to mould spores. Mould often poses a greater risk to children, who can become sensitised to it and develop allergic disease.⁶  

Common household moulds include cladosporium, penicillium, and aspergillus.^6,7 Mould will grow if spores land on places with excessive moisture, so damp locations like roofs, pipes, and walls are some key places where mould grows. Spores can be carried into the home very easily via attachment to clothing and pets, or they can enter through open doorways, windows, vents, heating and air conditioning systems.⁷ Mould growth is also more likely to occur during winter due to the wet and damp conditions.⁶ This allows mould to be a common household allergen if it is not cleared. 

If you have an allergy, you are sensitive to allergens. They are usually harmless substances that wrongly trigger your immune system because it thinks that they are dangerous. The immune system is a network of cells and tissues that protects us from illness. It reacts to allergens in an attempt to get rid of them from the body, and it does this by releasing molecules that cause inflammation. This results in the classical symptoms of an allergy, such as a runny nose, congestion, wheezing, red or itchy eyes or skin, or sneezing.^4,7 Additionally, your immune system makes antibodies against the mould allergens, which means that if you are re-exposed, you will continue to overreact to these harmless substances.⁴ Therefore, prolonged or repeated exposure to allergens can cause persistent inflammation and swelling of the nasal passages, which leads to chronic sinusitis.^6,7 

Diagnosing chronic sinusitis related to mould allergies

Doctors can use a range of techniques to identify and diagnose chronic sinusitis. They will often use a nasal endoscopy to look at the sinuses.^2,8 They will then take a sample from the affected tissues inside the nose to further investigate in the lab. When the sample gets to the lab, they will magnify the tissue under a microscope so that they can look for evidence of fungal infection and allergy.⁸ This includes:

• Evidence of an allergic reaction: Doctors will look for high levels of antibodies associated with the allergy known as IgE antibodies⁹
• Nasal polyps: Are painless, soft growths on the inside of your nose. They are usually not serious, but if they grow too big, they can block your nose and sinuses¹⁰
• Eosinophilic mucus: Eosinophils are a type of white blood cell that fight infection but cause inflammation. If lots of eosinophils are found in the sample taken from the endoscope, it can be a sign of chronic sinusitis¹¹
• Positive fungal stain: Doctors will use lab techniques to look for evidence of fungus in the sample to determine if sinusitis is caused by mould¹²
• Charcot-Layden crystals: These are slim, needle-shaped, microscopic crystals that are found in the mucus of patients with allergies^8,13

Doctors may also do a CT scan if they want to further confirm the diagnosis. The images will allow doctors to see sinus inflammation and to confirm the diagnosis of chronic sinusitis.^8,14 

How to prevent mould allergies and chronic sinusitis

Preventing mould growth at home is crucial for avoiding chronic sinusitis that can arise from mould allergies, and mould can be prevented by:⁷

• Keeping humidity levels low by using an air-conditioner or dehumidifier 
• Maintaining good airflow through the home 
• Using exhaust fans in the kitchen and bathroom allows air to vent outside of your home
• Fixing any leaks around the home, so that mould does not have any damp patches to grow on
• Use mould inhibitors before painting your walls
• Clean your house with mould-killing products. This is especially useful for removing mould in the bathroom
• Remove or replace any soaked items that cannot be dried immediately
• Quickly and fully dry out the home after a flood

If you do find mould inside your home, it should be removed immediately, and the moisture problem must be fixed.⁷ It can usually be done by yourself using household products like soap and water.⁷ However, if you are sensitive to mould exposure, then it is necessary that someone not at risk cleans it.⁷ People at risk include:⁷

• People with allergies, especially those sensitive to moulds
• People who have suppressed immune systems
• People with lung or respiratory diseases
• People who are at higher risk of developing fungal infections

Treatments for mould allergies and chronic sinusitis

Treating mould allergies and chronic sinusitis has no single approach. Treatments involve avoiding triggers and controlling inflammation.²

Medical interventions for chronic sinusitis

Medical interventions use medications to try to alleviate the symptoms of chronic sinusitis, such as:²

• Nasal steroids: a steroid medicine that is taken through the nose to prevent and treat symptoms associated with sinus conditions, like allergic rhinitis and hayfever. It can be taken as a spray or as drops. Steroids (or corticosteroids) work by reducing swelling and irritation inside the nose. The most common steroid used is fluticasone, also known by its brand names Flixonase, Avamys, and Nasofan. Some other nasal sprays like Dymista contain fluticasone mixed with other medicines, like antihistamines¹⁵ 
• Nasal saline irrigation: sometimes known as ‘nasal douching’ or ‘sinus rinse’. This is where a saline wash solution is squirted into the nose to clean the nasal passages. It can be done using commercially available kits^2,16
• Antihistamines: these are common medications that are used to relieve allergy symptoms. They are usually purchased over the counter at drugstores^2,17

Surgical Interventions for chronic sinusitis 

If medical interventions do not work, doctors may consider surgery:² 

• Functional endoscopic sinus surgery: This is an operation that is used to treat severe sinus problems. It is a safe surgery with few risks, but it is only used when previous medications have been unsuccessful. It is usually done under general anaesthesia and takes 30-60 minutes. It is an operation done on the inside of the nose, where a surgeon will use special telescopes and other surgical instruments to remove small amounts of bone and the swollen lining of the nose to unblock the sinuses. Nasal polyps can also be removed during this procedure¹⁸

Summary

• Chronic sinusitis is the persistent inflammation of the nasal passages and sinuses lasting 12 weeks or longer. It causes symptoms like nasal congestion, a runny nose, and facial or dental pain. This can make chronic sinusitis very uncomfortable to live with
• Mould is a type of fungus that grows in damp, moisture-rich environments. People can be allergic to mould
• Mould allergies can trigger chronic sinusitis, as prolonged allergic reactions to mould cause sinus inflammation
• Doctors can diagnose chronic sinusitis and mould allergies using a variety of tests
• To prevent allergic reactions to mould, you should take careful precautions to ensure mould does not grow in your home, or to clean it if it does grow
• Treatments for mould allergies and chronic sinusitis include nasal steroids, nasal saline irrigation, antihistamines, and possibly surgery