Symptoms of mold allergy

Symptoms of mold allergy

Scientists think there could be more than a million species of fungi. So far they’ve only identified a small fraction of them; mushrooms and toadstools, yeasts, mildews and molds. Of those, around 100 molds have been linked to mold allergy symptoms. With so many unknown unknowns, the true number could be higher.

You may come across mold every day, everywhere you go, both indoors and out. Most of the time you won’t even know it’s in the air. Until it gives you an itchy throat, runny nose, watery eyes and other mold allergy symptoms. Let’s find out how to recognize the telltale signs – and how to manage allergic reactions to mold.

Common mold allergy symptoms

Breathing in mold allergens often triggers the allergic reaction. As with other respiratory allergies, many symptoms affect your nose and airways. You may feel it straight away or there could be a delay. For instance, nasal congestion and breathing problems can build up over time.

  • Hay fever symptoms: a runny or stuffy nose, post-nasal drip and sneezing. Also known as seasonal allergic rhinitis
  • Eye irritation: On the surface and inside your eyelids giving you red, watery, itchy eyes
  • Lower respiratory symptoms: a cough, shortness of breath, tight chest and wheezing
  • Skin reactions: Dry patches, eczema (atopic dermatitis)

How to spot other
seasonal allergies

Seasonal allergy symptoms follow the seasons depending on whether you react to tree, grass or weed pollen, or mold

Mold spores: Other allergic conditions and symptoms

High levels of mold exposure, often through work, can lead to hypersensitivity pneumonitis (HP). Farmer’s lung is a type of HP caused by moldy hay. Symptoms include a cough, chest tightness, aches and chills, tiredness and losing weight. Humidifiers, heaters and central air-conditioning can also cause HP by spreading mold spores. There’s even a report of HP traced to a steamy sauna.

Some rare conditions involve both allergic and an inflammatory response to exposure to mold. Allergic bronchopulmonary aspergillosis can cause severe breathing problems. Allergic fungal sinusitis is inflammation of the sinuses.

Mold allergy symptoms from food

Eating certain foods can cause mild local symptoms if you have mold allergies. This is a cross-reaction known as oral allergy syndrome (OAS) or pollen food syndrome (PFS). Foods linked to mold include:

  • Mushroom
  • Yeast
  • Spinach

You might get itchy or swollen throat, lips, mouth or face but it’s usually mild. This allergic reaction happens because proteins in the food and the mold spores are very similar.

What causes my mold allergy symptoms?

It’s the mold spores. These self-contained seeds are even tinier than pollen grains. The mold releases them to float through the air looking for a damp spot to grow in. It’s just that sometimes you breathe them in instead. That can trigger mold allergy symptoms if your immune system decides the spores are a threat.

Bathroom medicine cabinet stocked with antihistamines, corticosteroids and decongestants to relieve symptoms

Guide to allergy medicines

How long do symptoms of mold allergy last?

That can depend on whether your symptoms are caused by indoor or outdoor molds. Most outdoor species tend to cause mold allergy symptoms in summer to early fall before going into hibernation when it gets cold.

But the world is warming and that seems to be lengthening the period that outdoor mold spores are in the air. Studies also suggest the quantity of spores released increases when carbon dioxide (CO2) levels are higher. These basic facts about climate change could extend the outdoor mold allergy season and make mold allergies more likely.

It’s a bit different for people allergic to indoor molds. Fungi depend on humidity to grow so they love your kitchen, bathroom and basement. And they can give you symptoms year round.

Risk factors for mold allergy symptoms

1. Outdoor conditions: You may already know to avoid damp woodland and piles of autumn leaves. Also the countryside during harvest. But it’s also a good idea to wear a dust mask in the garden during mold allergy season. Ideally, you’d get someone else to mow the lawn, as well as turn and spread your garden compost. Certain molds love it.

2. Raising the indoor mold count without realizing: Coats and shoes can trap spores when mold counts are high. So quarantine them by the door. Rub pets down with an old towel. Other carriers of mold spores include damp logs brought in for the fire.

3. A long DIY to-do list: Leaky roofs and rain gutters can create the ideal conditions for mold growth. Regularly clear out your gutters to drain standing water and fix any roof or plumbing issues. Clear flood damage too. Excessive moisture encourages rot.

4. Hidden mold growth: Clean mold from neglected areas such as behind kitchen cupboards and around window frames and fridge seals where they trap mold spores. Fridge condensation coils too if you can get to them. Keep houseplant numbers to a minimum and change the soil regularly to stop mold growing freely.

5. Poor ventilation: Cooking, washing and cleaning all make hot damp air. This can add to the humidity mold spores love. Close internal doors to stop it spreading round your home and use exhaust fans to vent excess moisture. Open windows when the mold count is likely to be low.


Get a hygrometer to measure indoor humidity levels and aim for 30% to 45%. Lowering humidity with a dehumidifier can slow mold growth which may lessen symptoms of mold allergy.

6. Geography: Your local climate can also have an effect on mold allergy symptoms. Get yourself a hygrometer to measure indoor humidity levels and aim for between 30% and 45%. Remember this can change over the course of a day so check again later. Lowering naturally high humidity with a dehumidifier can slow mold growth. And that may lessen year round symptoms of mold allergy.

7. Career choice: Farming is not the only occupation that can expose you to higher levels of mold than usual. So can working in dairies, greenhouses, flour mills and bakeries, and wineries. Also in the logging industry and repairing furniture.

8. Your family: If someone closely related to you has an allergy, that puts you at greater risk of developing allergies too.

Diagnosing mold allergy symptoms

Only your healthcare provider can say for sure if you’re allergic to mold. Try keeping a record of what you think could be mold allergy symptoms. Here are some details to include:

  • When do you experience symptoms, exactly?
  • How long do your symptoms last?
  • Do your mold allergy symptoms happen when you’re at home or outside?
  • Are they worse at a particular time of the year?
  • Are your symptoms worse at night?
  • Do you know where you were when symptoms developed?
Allergy quiz
Affected by mold or any other respiratory allergies? Take 2 minutes to check how well you’re controlling your symptoms. It could help you change how allergy affects your life.
Young woman holding a small dog that might be causing her allergy symptoms

After taking your medical history your healthcare provider may recommend a skin prick or blood test to help make a diagnosis. Tests can’t tell you when or where you were exposed to mold, which is why an allergy diary could be useful.

Medicines for mold allergy symptoms

Antihistamines, corticosteroids and decongestants are usually the go-to treatments for mold allergy symptoms. All are available over the counter and come in either topical (nasal spray, eye drops) or oral (tablets, liquid) form.

Antihistamine blocks the chemical (histamine) that causes many of your mold allergy symptoms. Corticosteroids reduce inflammation by copying hormones made by your body. And decongestants reduce swelling in your nose to help you to breathe better.

These options may only give temporary relief. If you find they aren’t effective enough your healthcare provider may prescribe stronger allergy medicine. Talk to them first before giving a child symptom relieving medications.

Long-term treatment for mold allergy symptoms

Immunotherapy is a treatment that can provide long-term relief from some mold allergies. Tiny doses of your trigger, repeated regularly over three to five years, can change the way your immune system reacts. The goal is to stop your mold allergy symptoms bothering you as much as possible.

Interested in learning more about mold allergy immunotherapy and whether it might be suitable for you? Try our Find a Doctor.

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