Aspergillus fumigatus
Allergy Facts, Symptoms, and Treatment


Found worldwide, Aspergillus fumigatus can colonize in the bronchial tracts of asthmatics, causing severe asthma and low lung functions and sometimes leading to severe conditions.

Within the larger Aspergillus genus, Aspergillus fumigatus is typically blue-green to gray in color with a woolly or cotton-like texture.3 Although Aspergillus is considered a seasonal outdoor mold that's often found on decaying vegetation, it can also colonize indoor environments such as air-conditioning systems, and it's one of the three most common indoor airborne fungi (along with Penicillium and Cladosporium).1,4,5 Aspergillus requires minimal moisture, and some species tolerate very dry conditions. As such, Aspergillus can grow rapidly in areas that can't support other molds. It produces small, dry, and easily aerosolized spores, which make them a significant indoor air contaminant.7 If you're allergic to Aspergillus fumigatus, you may experience symptoms after inhaling its spores.8

Where is Aspergillus found?

Aspergillus fumigatus can grow both indoors and outside.6 Outdoors it prefers environments such as soil, decomposing leaves, bird droppings, compost, wood chips, hay, stored grains and sweet potatoes, and hay and other crops.3,14 However, mold reproduces via spores, which can be transported by air, water, and insects.9,15 So even if a fungus originates outdoors, it often can enter a dwelling through a variety of means, including doorways, windows, vents, and heating and air conditioning systems.16 Aspergillus can grow on indoor surfaces such as ventilation ducts, floors, walls, potted plants, and household dust, and it's often found on foods rich in starch, such as rice, cereal, and bread. However, it has also been known to invade cereal grains and grow on processed and cured meats.3

It grows optimally in temps 37 to 43 C (roughly 99 to 109 F), but it can tolerate temps of 12 to 57 C (approximately 54 to 135 F).14 While Aspergillus fumigatus has almost worldwide distribution, in-home prevalence varies widely. For example, in the United States it was found in the air of 2.9 percent of homes in Southern California, but it was measured in 4.5 percent of homes in the Netherlands.17

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Are there other allergens I could be sensitized to?*

Some people with Aspergillus fumigatus allergy may also experience symptoms when exposed to other types of mold. This is called cross-reactivity and occurs when your body's immune system identifies the proteins, or components, in different substances as being structurally similar or biologically related, thus triggering a response.1

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

How do I manage my allergy?

If you are allergic to mold, your healthcare provider may recommend a plan that includes the following.8,9,20,21

  • Limit your outdoor time during seasons when mold is most active.
  • Wear a mask when disturbing or moving plant materials, and avoid raking and burning dry leaves.
  • Avoid barns, silos, hay, straw, and peat moss.
  • Use a certified asthma and allergy friendly filter attachment on your heating and air conditioning unit, and change filters regularly.
  • Employ dehumidifiers to lower indoor humidity levels to less than 45 percent to create an environment where mold is less likely to thrive.
  • Improve air flow through rooms by opening doors between spaces, moving furniture away from the walls, and operating fans.
  • Use exhaust fans in bathrooms and kitchens to pull moisture out of the rooms.
  • Fix any plumbing leaks, check windows for condensation, and remove sources of dampness.
  • Repair roof leaks, clean gutters, and ensure rainwater drains away from your dwelling.
  • Clean thoroughly and regularly, including sinks and tubs, refrigerator door gaskets, and garbage cans.
  • Remove clothes from washing machines promptly and clean rubber seals regularly.
  • Eliminate sources of dampness in basements, such as pipe leaks and groundwater seepage.
  • Run ventilation fans during and after showers and baths.
  • Remove any carpet from bathrooms and basements.

Your healthcare provider may direct you to take one of the following medications to improve your allergy symptoms:

  • Antihistamines are commonly used to reduce symptoms such as sneezing, itching, and runny nose.
  • Nasal corticosteroids are used to reduce swelling in the nose and block allergic reactions.
  • Oral and nasal spray decongestants can be employed to relieve stuffiness.
  • Anti-inflammatories such as montelukast, which can be effective in treating mold allergy.
  • Daily nasal lavage using a squeeze bottle filled with salt water can help clean out irritants and alleviate nasal symptoms.

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Common Symptoms

Mold allergy symptoms can range from mild to severe and vary person to person.8 Reactions can happen almost immediately after exposure, or they can be delayed. Symptoms are most common in mid-summer to early fall, but since molds grow both indoors and out, allergic reactions can occur all year.9

Symptoms typically include one or more of the following:8,10

  • Nasal congestion
  • Runny nose
  • Sneezing
  • Irritated, watery eyes
  • Coughing
  • Wheezing
  • Itchy eyes, nose, and throat
  • Dry, scaly skin

Mold sensitization is also a major risk factor for developing upper and lower respiratory diseases such as allergic rhinitis (aka hay fever) and allergic asthma.4,5

Aspergillus fumigatus can also colonize in the bronchial tracts of asthmatics, causing severe asthma and low lung functions, sometimes leading to severe conditions called allergic bronchopulmonary aspergillosis (ABPA) and allergic bronchopulmonary mycoses (ABPM).1 The condition involves both an allergic and inflammatory response to mold, and symptoms may include severe wheezing, coughing, shortness of breath, fever, weakness/malaise, and cough producing brown flecks or bloody mucus.2 In fact, Aspergillus fumigatus is the most frequent cause of 80 percent of all Aspergillus-related conditions including asthma, allergic sinusitis, hypersensitivity pneumonitis, severe asthma with fungal sensitization (SAFS), and ABPA.11 In terms of prevalence, ABPA has been reported to occur in up to 40 percent of individuals with chronic asthma and up to 10 percent of those with cystic fibrosis.12

In addition, other reactions to Aspergillus can include hypersensitivity pneumonitis (also known as extrinsic allergic alveolitis), which can lead to a chronic disease with irreversible lung damage. 5

A small percentage of asthmatics with inhaled mold allergy can also develop allergic urticaria (aka hives) when they eat or drink anything containing yeast or mold.13 In addition to causing allergic reactions, molds can lead to infections along with toxic reactions.14

How do I know if I'm allergic?*

Together with your symptom history, skin-prick testing or specific IgE blood testing can help determine if you are allergic to a particular allergen. If you are diagnosed with an allergy, your healthcare provider will work with you to create a management plan.

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

Is there a risk for a severe event?

Exposure and sensitization to Aspergillus fumigatus can promote the development and worsening of allergic diseases such as allergic rhinitis, asthma, and the severe condition allergic bronchopulmonary aspergillosis (ABPA). Your specific risk profile depends on which proteins you are allergic to.1

Knowing the proteins, or components, within each allergen that are triggering your symptoms can help guide your management plan. With that in mind, and based on your symptom history, your healthcare provider may suggest something called a specific IgE component test, which can help reveal your potential risk profile.1

Already have your specific IgE component test results?

Your component test results will include the name of the components (a series of letters and numbers). Your healthcare provider will likely review the results with you, but here you'll find an at-a-glance breakdown you can use as a reference. Simply match the component names to the list below to see what they mean in terms of symptom management.1,18,19

rAsp f 1

  • Indicates that symptoms may be caused specifically by Aspergillus.
  • Associated with increased risk for asthma and allergic bronchopulmonary aspergillosis (ABPA).

rAsp f 2, rAsp f 4

  • Indicates that the symptoms may be caused by Aspergillus.
  • Strong association with allergic bronchopulmonary aspergillosis (ABPA).

rAsp f 3

  • Associated with asthma and allergic bronchopulmonary aspergillosis (ABPA).
  • Molds other than Aspergillus may cause symptoms due to cross-reactivity.

rAsp f 6

  • Strong association with allergic bronchopulmonary aspergillosis (ABPA).
  • Molds other than Aspergillus may cause symptoms due to cross-reactivity.

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

  1. Fukutomi, Yuma & Taniguchi, Masami. (2015). Sensitization to fungal allergens: Resolved and unresolved issue. Allergology International. 145. 10.1016/j.alit.2015.05.007. Available from:
  2. Asthma and Allergy Foundation of America [Internet]. Arlington, VA: Asthma and Allergy Foundation of America; 2019 Jun. Available from:
  3. Ward J., Leduc C. Mold Busters [Internet]. Ottowa, ON, Canada: Bust Mold Inc.; 2018 Sep 9 [2019 Apr 16]. Available from:
  4. Ozdemir O (2015) Molds and Respiratory Allergy - Part 1. MOJ Immunol 2(2): 00045. DOI: 10.15406/moji.2015.02.00045. Available from:
  5. Simon-Nobbe B, Denk U, Pöll V, Rid R, Breitenbach M. The spectrum of fungal allergy. Int Arch Allergy Immunol. 2008;145(1):58-86. doi: 10.1159/000107578. Epub 2007 Aug 20. PMID: 17709917. Available from:
  6. EAACI, et al. Molecular allergology user's guide. Pediatric Allergy Immunol. 2016 May;27 Suppl 23:1-250. do: 10.1111/pai.12563. PMID: 27288833. (131-136 p.) Available from:
  7. Abbott, S. Molds and other fungi in indoor environments: Summary of biology, known health effects and references. (2003). Available from:
  8. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Apr 3. Available from:
  9. Asthma and Allergy Foundation of America [Internet]. Arlington, VA: Asthma and Allergy Foundation of America; 2015 Oct. Available from:
  10. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2018 Apr 23. Available from:
  11. Chaudhary N, Marr KA. Impact of Aspergillus fumigatus in allergic airway diseases. Clin Transl Allergy. 2011 Jun 10;1(1):4. doi: 10.1186/2045-7022-1-4. PMID: 22410255; PMCID: PMC3294627. Available from:
  12. Goldman DL, Huffnagle GB. Potential contribution of fungal infection and colonization to the development of allergy. Med Mycol. 2009;47(5):445-56. doi: 10.1080/13693780802641904. PMID: 19384753. Available from:
  13. GI Society [Internet]. Vancouver, BC, Canada: Canadian Society of Intestinal Research; 2004 Mar/Apr. Available from:
  14. Storey E. Guidance for clinicians on the recognition and management of health effects related to mold exposure and moisture indoors. Farmington, CT: University of Connecticut Health Center, Division of Occupational and Environmental Medicine, Center for Indoor Environments and Health; 2004.
  15. United States Department of Agriculture [Internet]. [place unknown]: United States Department of Agriculture; 2013 Aug. Available from:,that%20can%20make%20you%20sick.
  16. Centers for Disease Control and Prevention [Internet]. Atlanta, GA: National Center for Environmental Health; 2020 Aug 11. Available from:
  17. Piecková E, Jesenská Z. Microscopic fungi in dwellings and their health implications in humans. Ann Agric Environ Med. 1999;6(1):1-11. PMID: 10384209. Available from:
  18. Kurup VP, Banerjee B, Hemmann S, et al. Selected recombinant Aspergillus fumigatus allergens bind specifically to IgE in ABPA. Clinical and Experimental Allergy : Journal of the British Society for Allergy and Clinical Immunology. 2000 Jul;30(7):988-993. DOI: 10.1046/j.1365-2222.2000.00837.x.
  19. Crameri R, Hemmann S, Ismail C, Menz G, Blaser K, Disease-specific recombinant allergens for the diagnosis of allergic bronchopulmonary aspergillosis., International Immunology, Volume 10, Issue 8, Aug 1998, Pages 1211 1216,
  20. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Apr 3. Available from:
  21. Nationwide Children s Hospital [Internet]. Columbus, OH: Nationwide Children s Hospital; 1976 [2018 Oct]. Available from: