What are mould allergies?
Mould is a kind of fungus. It’s nature’s cleaner upper, breaking down dead organic matter. And mould grows everywhere. It’s on the loose outdoors on logs and in piles of autumn leaves. And homes can be downright mouldy too, often without us realising it. You’ll find it in basements, on rotting window frames, anywhere near a leaky pipe. Mould thrives where it’s damp and can grow on almost anything.
It can also give you hay fever symptoms. Here’s all you need to know about mould allergies and how to manage them.
What are mould allergies?
Mould allergies happen because your immune system overreacts to mould seeds called spores. Spores are even tinier than the pollen grains better known for causing hay fever. They float through the air as part of the mould’s reproductive process. Some spores spread on dry days in the wind, others when it’s wet, in fog or dew. You breathe in the invisible spores. And that sets off the allergic reaction as your body tries to get rid of something it thinks could do you harm.
Where do mould allergies strike?
That’s the thing, you may get symptoms almost anywhere. It partly depends on which mould you’re allergic to. Garden sheds and compost heaps are two more hotspots for outdoor moulds. But moulds don’t always pick inside or out and stick to it. Which can be annoying if you have mould allergies.
Mould spores waft into buildings – your home, workplace, school – through an open door or window. Or via your heating or air conditioner. Like pollen, spores can also cling to clothing, shoes and pets, and get carried inside that way. The first clue to the unwelcome guest might be a musty smell. Or you may start getting symptoms of an allergic reaction.
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When are mould allergies worst?
Mould likes humidity. Outdoor species tend to cause seasonal allergy symptoms from July to early fall. Most outdoor moulds hibernate during winter. It’s a little different in climates where the conditions are almost always perfect. There may be no specific allergy season. That’s how it is with indoor mould allergies. You could be affected year round.
The greenhouse gas carbon dioxide also seems to affect mould allergies. High CO2 levels are known to make one common allergenic mould Alternaria alternata release more spores. And those spores contain more of the allergenic protein than when CO2 levels are lower. So climate change is likely to make mould allergies worse.
Mould spores: the troublemakers
There are many different sorts of mould but only a few dozen seem to cause respiratory allergies. Here are some common moulds that make people sneeze:
- Cladosporium herbarum: Number one cause of mould allergies, found in fridges, on food, window frames and in houses with damp problems. Spores travel easily through the air and into buildings.
- Penicillium notatum: The blue in blue cheese (yum) and on stale bread (less so). Away from the home you’ll find this mould in soil, stored cereal crops and hay. It’s known for indoor mould allergies and peaks during winter and spring.
- Alternaria alternata: Generally an outdoor mould that grows when it’s warm. It’s found in soil, food and fabrics such as clothes or curtains.
- Aspergillus fumigatus: Mould found in soil, fallen leaves and dead plants, rotten veg, tobacco and sweet potatoes in store. It’s also in bird poo. Can cause lower respiratory problems.
- Trichophyton rubrum and Pityrosporum orbiculare: Not mould but other types of fungi that may trigger an immune response. Both can cause atopic dermatitis (eczema).
Mould allergy symptoms
Breathing in mould spores can cause hay fever symptoms (allergic rhinitis) right away. Or there may be a delay. Your stuffy nose and lower respiratory symptoms can also build over time. Typically, you may get any or all of these if you have mould allergy:
- Stuffy nose (nasal congestion)
- Runny nose
- Sneezing
- Itchy nose
- Itchy, red or watery eyes
- Post-nasal drip (the feeling of mucus moving down the back of your throat)
- Cough
- Tight chest or wheezing
- Sinus inflammation/pain
- Dry skin, atopic dermatitis
Mould allergies and eating mushrooms
Food fungi don’t usually cause hay fever with their spores. But eating them may give you a tingly mouth if you have mould allergies. It can also happen with yeast, which is another fungus. And with spinach, which might surprise you.
This is a type of cross-reaction known as oral allergy syndrome. It happens because proteins in that food and in your trigger allergen are very similar. The reaction affects your mouth, throat, lips or face and is usually mild. But it’s still a good idea to talk to your GP about it.
Other conditions caused by allergy to mould
Hypersensitivity pneumonitis (HP) is an allergic condition that causes symptoms such as a cough, tight chest, chills, body aches, tiredness and weight loss. It tends to affect people exposed to high levels of mould at work. Farmer’s lung is a type of HP linked to breathing in spores from mouldy hay or straw. Fungi dispersed by humidifiers, central heating or air-conditioners, and even the sauna, can cause it too.
Less common is a condition called allergic bronchopulmonary aspergillosis (ABPA). This inflammatory and allergic response to mould can cause severe breathing symptoms. Allergic fungal sinusitis is inflammation of the sinuses.
Diagnosing mould allergies
Talk to your GP if you think you may have mould allergies. You’ll need to have your medical history ready, including details of when and where you get symptoms. They may suggest a skin prick test or allergy blood test to help make a diagnosis. You can also use our Home Allergy Test.
7 simple ways to avoid mould allergies
The key to reducing allergy symptoms is avoiding exposure to mould. So check out these tips.
- Don’t go down to the woods today: If it’s damp, you’re (almost) sure of mould allergy symptoms. Especially if you kick over piles of dead leaves or make a den out of fallen branches. Try to avoid the countryside during harvest too, especially if it’s clear and windy when mould counts are likely to be high. And stay away from buildings where cereal or hay is stored.
- Be careful with those green fingers: Keep houseplants to a minimum and change the soil regularly. If mould allergy symptoms are bothering you, wear a mask to do any gardening. And get someone else to turn the compost and spread it when the time comes.
- Don’t bring mould indoors: Outdoor clothes and shoes can trap mould spores. Store them near the door so you don’t carry allergens into your living spaces. Avoid keeping firewood in a damp shed. Chances are it’ll get damp too and we know what that means.
- Monitor your home’s humidity: Buy a hygrometer to measure your indoor humidity levels. Anything between 30% and 45% is fine. Above 50% creates a breeding ground for fungi. Central air-conditioning or using a dehumidifier regularly can help bring humidity down. Just remember to clean the filters.
- Ventilate well to reduce mould: Use an extractor fan in areas where there may be excess moisture. Like the kitchen, bathroom and laundry room (if you’ve got one). Open windows and close internal doors when cooking or washing to stop steam escaping to other rooms.
- Look for leaks and fix them: Plumbing leaks can create damp areas on walls and ceilings, and places you can’t see like inside cupboards. So fix problems before moulds grow. If it’s too late, strip the wallpaper and repair. Leaky roofs are prime targets for mould. And rain gutters can fill up with rotten leaves and other debris causing yet more leaks – so keep them clear. All this can help prevent mould growth.
- Clean mouldy hot spots: That means fridge, dishwasher and washing machine seals; refrigerator drip-pans; window frames; the walls behind kitchen units and cupboards; the grout between bathroom tiles. You can remove mould with soap and water, standard cleaning products or a diluted bleach solution. Make sure you open windows and doors for fresh air if you’re using bleach. And wear gloves and eye protection.
Let’s be honest, some of these tips to reduce mould are a chore and others feel like it too. But mould exposure can affect sleep, make you snore and cause day-time drowsiness even if you don’t have allergies. So keeping it out of your home could have other benefits too.
Treatments for mould allergies
There are natural remedies you can try before taking medication for mould allergies. Stuck in a damp basement? Get yourself a nasal douche. Rinsing your nasal passages with saline will help to clear irritants. This may reduce allergy symptoms.
If these drug-free treatments aren’t effective enough you can try the symptom-relieving medications. Antihistamine and corticosteroids are available over the counter or on prescription. They come as tablets, liquids, nasal sprays and eye drops. Some nasal sprays combine corticosteroid and antihistamine. A decongestant may be helpful too. Ask your pharmacy or GP for advice on mould allergy medicines.
Is there a cure for mould allergies?
There is a type of treatment that can provide long-term relief from some allergies. It’s not a cure but immunotherapy can change the way you react to an allergen. Treatment involves giving you repeated tiny doses of your trigger about three years. The results vary but the aim is for you to have much milder if any symptoms by the end.
Immunotherapy is not available for every mould allergy. But research suggests similarities between closely-related moulds might make it applicable to people allergic to other species too.
