Mucor Racemosus
Allergy Facts, Symptoms, and Treatment

While initially white or yellow in color with a fluffy texture, Mucor mold colonies grow rapidly and turn a dark or olive-gray color as spores develop.1 If allergic individuals inhale these spores, they may experience allergy symptoms.2 Mucor are often found in soil, plant debris, and dung.3 However, the mold also grows in indoor environments, as colonies have been found in homes, schools, and offices in mediums such as house dust, mattresses, carpet, and ventilation ducts.1

Mucor can cause a wide range of human diseases, known as mucormycoses. While the diseases are often fatal, they usually only occur in people already suffering from a separate disease.1 Worldwide, Mucor prevalence ranges widely. For example, 40 percent of allergic Scandinavian patients showed Mucor sensitivity while only 3.8 percent of asthmatics in the Netherlands experienced Mucor sensitivity during skin testing.4

Where is Mucor found?

Mucor is often found in soil, plant debris, stored grains, dairy products, and dung, as well as on plants and decaying fruits and vegetables.1,3 However, mold reproduces via spores, which can be transported by air, water, and insects.5,10 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.11 Mucor colonies have been found in homes, hospitals, schools, and offices in mediums such as house dust, carpet, mattresses, and ventilation ducts.1,12 Although some species can grow in temperatures up to 42 C (roughly 108 F), which means they may live within animals and humans, Mucor racemosus doesn't thrive in temps higher than 32 C (roughly 89 F).1,4 So although this species can cause infections, they're usually limited to the skin, which is cooler than the body's interior.1 Plus, Mucor is used in the production of fermented foods and beverages in Asia.4

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Are there other allergens I could be sensitized to?*

Some people with Mucor racemosus 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.13

*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.2,5,15,16

  • 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.5

Symptoms typically include one or more of the following:2,6

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

Most mold allergy reactions involve the preceding symptoms.2 However, mold sensitization is also a major risk factor for developing upper and lower respiratory diseases such as asthma.7

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.8 In addition to causing allergic reactions, molds can also lead to infections along with toxic reactions.9


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.14 However, exposure and sensitization to fungal allergens can promote the development and worsening of allergic diseases such as allergic rhinitis and asthma.13

  1. Ward J., Leduc C. Mold Busters [Internet]. Ottowa, ON, Canada: Bust Mold Inc.; 2019 Mar 4 [2019 Jun 7]. Available from:
  2. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Apr 3. Available from:
  3. Abbott, S. Molds and other fungi in indoor environments: Summary of biology, known health effects and references. (2003). Available from:
  4. Weber RW. Allergen of the month--mucor. Ann Allergy Asthma Immunol. 2015 Aug;115(2):A15. doi: 10.1016/j.anai.2015.06.023. PMID: 26250774. Available from:
  5. Asthma and Allergy Foundation of America [Internet]. Arlington, VA: Asthma and Allergy Foundation of America; 2015 Oct. Available from:
  6. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2018 Apr 23. Available from:
  7. Ozdemir O (2015) Molds and Respiratory Allergy - Part 1. MOJ Immunol 2(2): 00045. DOI: 10.15406/moji.2015.02.00045. Available from:
  8. GI Society [Internet]. Vancouver, BC, Canada: Canadian Society of Intestinal Research; 2004 Mar/Apr. Available from:
  9. 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.
  10. United States Department of Agriculture [Internet]. [place unknown]: United States Department of Agriculture; 2013 Aug. Available from:,that%20can%20make%20you%20sick.
  11. Centers for Disease Control and Prevention [Internet]. Atlanta, GA: National Center for Environmental Health; 2020 Aug 11. Available from:
  12. Levetin E, Horner WE, Scott JA; Environmental Allergens Workgroup. Taxonomy of Allergenic Fungi. J Allergy Clin Immunol Pract. 2016 May-Jun;4(3):375-385.e1. doi: 10.1016/j.jaip.2015.10.012. Epub 2015 Dec 24. PMID: 26725152. Available from:
  13. 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:
  14. 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:
  15. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Apr 3. Available from:
  16. Nationwide Children s Hospital [Internet]. Columbus, OH: Nationwide Children s Hospital; 1976 [2018 Oct]. Available from: