Am I Allergic to Mold?

The term “mold” refers to fungi that are a part of our natural environment. There are hundreds of thousands of mold species around us on earth. They are found anywhere that has lots of moisture, both indoors and outdoors. Most molds aren’t a threat to human health and live in harmony with us. 

But molds can potentially trigger allergies and asthma — they can also make asthma worse. We will discuss the relationship between mold and different allergic diseases as well as testing and treatment for mold allergy. 

What are the symptoms of mold allergy?  

Because mold is all around us and in the air, we are all breathing in mold spores. Some people can become sensitized to mold. This means that they have an allergic response to proteins found on molds and mold spores. Their immune systems produce the allergic antibody IgE, which targets specific molds.

While there are hundreds of thousands of species of mold, very few of them can cause allergies. According to the International Union of Immunological Societies (IUIS), only a small percentage of mold species are allergenic. The most common ones are Alternaria and Cladosporium among outdoor molds, and Penicillium and Aspergillus among indoor molds.

Overall, molds aren’t considered very powerful allergens. The strongest airborne allergens are cat dander, dust, and pollen. And at the very bottom of the list is mold. This means that exposure to mold is much less likely than other allergens to cause an allergic response at the same dose.

Mold allergy symptoms are the same as those of other airborne allergens. These include:

• Allergic rhinitis: sneezing, itching, runny nose, itchy eyes, stuffy nose

• Asthma: shortness of breath, wheezing, cough, chest tightness

• More serious hypersensitivity disorders: such as allergic fungal sinusitis or allergic bronchopulmonary aspergillosis, which cause similar but more severe symptoms

These symptoms can worsen with indoor mold exposure or with high outdoor mold counts. Outdoor mold counts are higher in hot and humid summers, especially right after it rains.

People with asthma and allergies can also experience worsening symptoms after exposure to mold — even if they aren’t actually allergic to mold.  

How do I test for a mold allergy?

Having mold in your home does not mean that you are allergic to mold or have a mold-related disease. Antibody testing can help if you have allergy or asthma symptoms and there’s concern for mold allergy. Your allergist would look for specific IgE that respond to mold through skin testing or blood testing. No other tests have been proven to be clinically useful for mold allergy.

The following tests can detect mold allergies: 

• Skin tests: These include skin prick tests and intradermal tests. 

• Serum (blood) tests: These look for specific IgE antibodies to various molds.

Allergy testing can be helpful, but it’s hard to be certain of a mold allergy diagnosis. Here are a few tips to help you understand the results:

• If your allergy testing shows that you are sensitive to mold, and you suffer from nasal symptoms or asthma, then mold may be causing your allergies.

• But if you have an allergy test that shows mold and other allergens, this does not mean for sure that your symptoms are related to a mold allergy. Dust mites and pet dander are often present in homes with mold, and these are much more powerful allergens than mold spores. 

• If your allergy testing only shows mold and not other indoor allergens, it’s more likely that you have a true mold allergy.

On the other hand, even if you have visible mold in your house, a negative allergy test to mold means that your symptoms are likely not due to mold. Another allergen such as dust mite or pet dander may be causing your symptoms.

The CDC does not recommend environmental testing for mold — even if there’s water damage or visible mold in your home. This is because there’s no scientific evidence to support it. There are no studies showing any relevance between test results and clinical symptoms. Testing the home is also expensive. No matter the type of mold, you should get rid of it. 

How do you treat a mold allergy? 

Mold allergy treatment uses the same principles as all airborne allergy treatments. Treatment consists of avoiding the allergen and taking medications and/or allergen immunotherapy (or allergy shots). 

Avoidance of exposure

With any allergy, it’s always best to avoid what you are allergic to. The best way to avoid mold exposure is to get rid of any mold, a process called “mold remediation.” Controlling moisture in your home is also important, which includes the following:

• Fix any areas of water damage or leaks in the home. 

• Clean areas of visible mold with a solution of chlorine bleach and water.

• Use a dehumidifier to keep the humidity in your home low (between 40% to 50%). You can use a hygrometer to monitor humidity levels.

It also helps to stay indoors on days with a high mold count. The mold count outdoors measures the number of mold spores in one cubic meter of air. You can track it through the National Allergy Bureau or local agencies.

Medications

If you have nasal allergy symptoms, your provider may recommend antihistamines such as cetirizine (Zyrtec) or fexofenadine (Allegra) and/or intranasal steroids such as fluticasone (Flonase) or budesonide. Your healthcare team may treat asthma symptoms with a regimen of inhalers. More severe cases may need biologic medications. 

Immunotherapy 

Your allergist may also recommend mold allergen immunotherapy (allergy shots) to desensitize you to molds. But it must be noted that limited studies exist on mold immunotherapy. Most studies have focused on Alternaria and Cladosporium species. Overall, experts believe that immunotherapy doesn’t work as well for mold allergy as it does for other allergens like dust, mite, or pet dander. More studies are needed to clarify the role of mold immunotherapy for those who suffer from allergies. 

Do air purifiers help reduce mold exposure?

Air purifiers reduce levels of indoor airborne particles — including mold that can trigger allergies. You may use them along with other environmental control measures to decrease mold exposure. But you can’t use an air purifier by itself to completely control or eliminate mold allergy symptoms. It isn’t a “treatment” in and of itself, but it can help to prevent allergies from worsening.

Are humidifiers OK to use if I have a mold allergy?

A problem with humidifiers is that bacteria and mold can contaminate them. When this happens, the humidifier releases bacteria and mold into the air, which can actually cause or worsen illness. “Humidifier lung” describes a kind of lung inflammation that occurs when you inhale these germs. If you do use a humidifier, it’s important to keep the machine clean and change the filter regularly. 

What is ‘toxic mold syndrome’?

Mold allergies are very different from “toxic mold syndrome.” Toxic fungal products called “mycotoxins” cause toxic mold syndrome. There have been a lot of recent reports on this diagnosis, also referred to as “toxic black mold.” The main species to blame is Stachybotrys chartarum, which is a greenish-black mold. The symptoms of toxic mold syndrome are often subjective and difficult to measure. Many experts believe it’s an unproven condition that lacks strong evidence.   

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Written by:

Merin Kuruvilla, MD

Merin Kuruvilla, MD, is a board-certified allergist/immunologist at Emory University in Atlanta. She has authored several peer-reviewed publications in the field.

Edited by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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