What are mold allergies?

Mold is a kind of fungus. It’s nature’s cleaner upper, breaking down dead organic matter. And mold grows everywhere. It’s on the loose outdoors on logs and in piles of autumn leaves. And homes can be downright moldy too, often without us realizing it. You’ll find it in basements, on rotting window frames, anywhere near a leaky pipe. Mold 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 mold allergies and how to manage them.

What are mold allergies?

Mold allergies happen because your immune system overreacts to mold 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 mold’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 mold allergies strike?

So, what is hay fever then?

What are mold allergies?

What are mold allergies? A condition that can take the fun out of walks like this through autumn leaves full of sneezy spores

What are mold allergies?

Mold is a kind of fungus. It’s nature’s cleaner upper, breaking down dead organic matter. And mold grows everywhere. It’s on the loose outdoors on logs and in piles of autumn leaves. And homes can be downright moldy too, often without us realizing it. You’ll find it in basements, on rotting window frames, anywhere near a leaky pipe.

Hay fever is a global health issue and the number of people affected is rising. It can make you feel miserable and affect your performance at work or school. Hay fever can affect your sleep, which can make you feel tired the next day.

Let’s take a look at what hay fever is, find out what causes it and discover what hay fever treatments are available.

What is hayfever?

What are mold allergies? A condition that can take the fun out of walks like this through autumn leaves full of sneezy spores

Mold 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 mold allergies and how to manage them.

What are mold allergies?

Mold allergies happen because your immune system overreacts to mold 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 mold’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.

Seasonal allergic rhinitis

That’s the thing, you may get symptoms almost anywhere. It partly depends on which mold you’re allergic to. Garden sheds and compost heaps are two more hotspots for outdoor molds. But molds don’t always pick inside or out and stick to it. Which can be annoying if you have mold allergies.

That’s the thing, you may get symptoms almost anywhere. It partly depends on which mold you’re allergic to. Garden sheds and compost heaps are two more hotspots for outdoor molds. But molds don’t always pick inside or out and stick to it. Which can be annoying if you have mold allergies.

Mold 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.

Did you Know...?

  • Fungi are among the most widely spread living things on Earth
  • Thereare about 144,000 known species but only a few dozen cause allergy symptoms
  • Christmas tree allergy could actually be down to mold spores on the tree
  • Mold is a fast mover. You have 24–48 hours to clean and dry a flooded home and stop it moving in
  • That musty smell in a damp room is actually “mold farts” – the result of the organism digesting something

When are mold allergies worst?

Mold likes humidity. Outdoor species tend to cause seasonal allergy symptoms from July to early fall. Most outdoor molds 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 mold allergies. You could be affected year round.

The greenhouse gas carbon dioxide also seems to affect mold allergies. High CO2 levels are known to make one common allergenic mold Alternaria alternata release more spores. And those spores contain more of the allergenic protein than when carbon dioxide (CO2) levels are lower. So climate change is likely to make mold allergies worse.

Mold spores: the troublemakers

There are many different sorts of mold but only a few dozen seem to cause respiratory allergies. Here are some common molds that make people sneeze:

  • Cladosporium herbarum: Number one cause of mold 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 mold in soil, stored cereal crops and hay. It’s known for indoor mold allergies and peaks during winter and spring.
  • Alternaria alternata: Generally an outdoor mold that grows when it’s warm. It’s found in soil, food and fabrics such as clothes or curtains.
  • Aspergillus fumigatus: Mold found in soil, fallen leaves and dead plants, rotten veg, tobacco and sweet potatoes in store. It’s also in bird poop. Can cause lower respiratory problems.
  • Trichophyton rubrumand Pityrosporum orbiculare: Not mold but other types of fungi that may trigger an immune response. Both can cause atopic dermatitis (eczema).

Mold allergy symptoms

Breathing in mold 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 mold 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
Like mold, ragweed is very widespread and can cause annoying allergy symptoms from late summer until the weather turns cold

Ragweed: also a
late summer allergy pest

Mold allergy symptoms

Breathing in mold 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 mold 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
Like mold, ragweed is very widespread and can cause annoying allergy symptoms from late summer until the weather turns cold

Ragweed: also a late
summer allergy pest

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Mold 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 mold 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 healthcare provider about it.

Man at his office desk blowing his nose – maybe he has dust mite allergy or reacts to an indoor mold

Mold, or could it be
dust mite allergy?

Other conditions caused by allergy to mold

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 mold at work. Farmer’s lung is a type of HP linked to breathing in spores from moldy 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 mold can cause severe breathing symptoms. Allergic fungal sinusitis is inflammation of the sinuses. 

Diagnosing mold allergies

Talk to your healthcare provider if you think you may have mold 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.

Man at his office desk blowing his nose – maybe he has dust mite allergy or reacts to an indoor mold

Mold, or could it be
dust mite allergy?

Other conditions caused by allergy to mold

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 mold at work.

Farmer’s lung is a type of HP linked to breathing in spores from moldy 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 mold can cause severe breathing symptoms. Allergic fungal sinusitis is inflammation of the sinuses. 

Diagnosing mold allergies

Talk to your healthcare provider if you think you may have mold 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.

7 simple ways to avoid mold allergies

The key to reducing allergy symptoms is avoiding exposure to mold. So check out these tips.

1. Don’t go down to the woods today: If it’s damp, you’re (almost) sure of mold 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 mold counts are likely to be high. And stay away from buildings where cereal or hay is stored.

2. Be careful with that green thumb: Keep houseplants to a minimum and change the soil regularly. If mold 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.

Find a doctor

Find a doctor

Allergy can be confusing. If you have symptoms but don’t know what’s causing them, why not talk to a doctor? Our doc finder tool can help you find one.

3. Don’tbring mold indoors: Outdoor clothes and shoes can trap mold 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.

4. 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.

5. Ventilate well to reduce mold: Use an exhaust 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.

6. 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 molds grow. If it’s too late, strip the wallpaper and repair. Leaky roofs are prime targets for mold. 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 mold growth.

7. Clean moldy 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 mold 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 mold are a chore and others feel like it too. But mold 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.

Smiling young girl with her head tilted back, about to get allergy eyedrops to soothe her itchy, red and watery eyes

Simple guide to
kids’ allergy medicine

Treatments for mold allergies

There are natural remedies you can try before taking medication for mold 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.

Smiling young girl with her head tilted back, about to get allergy eyedrops to soothe her itchy, red and watery eyes

Simple guide to
kids’ allergy medicine

Treatments for mold allergies

There are natural remedies you can try before taking medication for mold 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 as over-the-counter or with a 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 healthcare provider for advice on mold allergy medicines.

Is there a cure for mold 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 over three to five 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 mold allergy. But research suggests similarities between closely-related molds might make it applicable to people allergic to other species too.

If these drug-free treatments aren’t effective enough you can try the symptom-relieving medications. Antihistamine and corticosteroids are available as over-the-counter or with a 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 healthcare provider for advice on mold allergy medicines.

Is there a cure for mold 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 over three to five 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 mold allergy. But research suggests similarities between closely-related molds might make it applicable to people allergic to other species too.

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