Allergen Fact Sheets

Cladosporium herbarum Allergen Facts, Symptoms, and Treatment

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Cladosporium Herbarum

Cladosporium is a major source of inhaled mold allergy, which means those sensitized to C. herbarum may experience symptoms after breathing in its spores.1,2 While it's considered a seasonal outdoor mold and is found worldwide mainly on plants, in soil, and on food, it can also colonize a host of indoor surfaces.3-5 In fact, Cladosporium is among the top three most common indoor airborne fungi (along with Penicillium and Aspergillus). That said, indoor concentrations of this mold seem to increase in conjunction with rising outdoor concentrations.6

Relatively slow growing, Cladosporium displays a variety of colors, including olive-brown, black-brown, brown, buff, and gray.7 Production of its comparatively dry spores typically peak in the afternoon, which may increase outdoor exposure symptoms.8 In terms of prevalence, studies vary widely, but one skin test study revealed an allergic reaction in 42 percent of children under age 4.9

Where is Cladosporium found?

Although Cladosporium species are abundant globally, they are dominant in temperate climates.14 For Cladosporium herbarum, the optimal temperature for growth is 18 to 28 C (roughly 64 to 82 F), but it can grow below 0 C (32 F) and can even live on frozen meat.9 Found mainly on plants, in soil, and on food, C. herbarum can also colonize a host of indoor surfaces such as window panes and insulation in heating and cooling systems.3,5 That's because mold reproduces via spores, which can be transported by air, water, and insects.10,15 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

While this mold can be clearly visible at times, at other times its undetectable by the naked eye. It can often be found in bathrooms and basements and on surfaces such as fabrics, wood, wallpaper, carpets, rugs, windowsills, grills, upholstered furniture, faucets, and curtains. Cladosporium is extremely widespread indoors, for according to some air-pollution studies, all tested homes in Canada contained Cladosporium spores, as did 70 percent of similarly tested U.S. homes.9

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Are there other allergens I could be sensitized to?*

Some people with Cladosporium herbarum 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.6

*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.2,10,18,19

  • 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.2 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.10

Symptoms typically include one or more of the following:2,11

  • 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.4,12

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.3

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?

There are no credible reports in medical literature documenting indoor exposure to molds as a cause of anaphylaxis.17 However, exposure and sensitization to fungal allergens can promote the development and worsening of allergic diseases such as allergic rhinitis and asthma.6

  1. Pomés A, Chapman MD, Wünschmann S. Indoor Allergens and Allergic Respiratory Disease. Curr Allergy Asthma Rep. 2016 Jun;16(6):43. doi: 10.1007/s11882-016-0622-9. PMID: 27184001; PMCID: PMC4976688.
  2. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Apr 3. Available from: https://www.mayoclinic.org/diseases-conditions/mold-allergy/symptoms-causes/syc-20351519.
  3. 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.
  4. Ozdemir O (2015) Molds and Respiratory Allergy - Part 1. MOJ Immunol 2(2): 00045. DOI: 10.15406/moji.2015.02.00045. Available from: https://medcraveonline.com/MOJI/MOJI-02-00045.pdf.
  5. 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: https://pubmed.ncbi.nlm.nih.gov/10384209.
  6. 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: https://www.sciencedirect.com/science/article/pii/S1323893015001161?via%3Dihub.
  7. Mycology Online [Internet]. Adelaide, Australia: The University of Adelaide; 2016 Dec 15. Available from: https://mycology.adelaide.edu.au/descriptions/hyphomycetes/cladosporium.
  8. Baxi SN, Phipatanakul W. The role of allergen exposure and avoidance in asthma. Adolesc Med State Art Rev. 2010 Apr;21(1):57-71, viii-ix. PMID: 20568555; PMCID: PMC2975603. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975603.
  9. Ward J., Leduc C. Mold Busters [Internet]. Ottowa, ON, Canada: Bust Mold Inc.; 2019 Jan 4 [2019 May 17]. Available from: https://www.bustmold.com/resources/mold-library/cladosporium.
  10. Asthma and Allergy Foundation of America [Internet]. Arlington, VA: Asthma and Allergy Foundation of America; 2015 Oct. Available from: https://www.aafa.org/mold-allergy.
  11. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2018 Apr 23. Available from: https://acaai.org/allergies/types/mold-allergy.
  12. 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: https://www.karger.com/Article/FullText/107578.
  13. GI Society [Internet]. Vancouver, BC, Canada: Canadian Society of Intestinal Research; 2004 Mar/Apr. Available from: https://badgut.org/information-centre/health-nutrition/yeast-and-mould-allergy.
  14. Knutsen AP, Bush RK, Demain JG, Denning DW, Dixit A, Fairs A, Greenberger PA, Kariuki B, Kita H, Kurup VP, Moss RB, Niven RM, Pashley CH, Slavin RG, Vijay HM, Wardlaw AJ. Fungi and allergic lower respiratory tract diseases. J Allergy Clin Immunol. 2012 Feb;129(2):280-91; quiz 292-3. doi: 10.1016/j.jaci.2011.12.970. PMID: 22284927. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0091-6749(11)02939-3.
  15. United States Department of Agriculture [Internet]. [place unknown]: United States Department of Agriculture; 2013 Aug. Available from: https://www.fsis.usda.gov/wps/wcm/connect/a87cdc2c-6ddd-49f0-bd1f-393086742e68/Molds_on_Food.pdf?MOD=AJPERES#:~:text=The%20spores%20give%20mold%20the%20color%20you%20see.&text=Foods%20that%20are%20moldy%20may,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: https://www.cdc.gov/mold/faqs.htm.
  17. Bush RK, Portnoy JM, Saxon A, Terr AI, Wood RA. The medical effects of mold exposure. J Allergy Clin Immunol. 2006 Feb;117(2):326-33. doi: 10.1016/j.jaci.2005.12.001. Erratum in: J Allergy Clin Immunol. 2006 Jun;117(6):1373. Erratum in: J Allergy Clin Immunol. 2014 Nov;134(5):1217. PMID: 16514772. Available from: https://www.jacionline.org/article/S0091-6749(05)02591-1/fulltext.
  18. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Apr 3. Available from: https://www.mayoclinic.org/diseases-conditions/mold-allergy/diagnosis-treatment/drc-20351525.
  19. Nationwide Children’s Hospital [Internet]. Columbus, OH: Nationwide Children’s Hospital; 1976 [2018 Oct]. Available from: https://www.nationwidechildrens.org/conditions/allergy-to-mold.