Mold Allergy


Photo of woman looking at mold on a wall

What is an allergy to mold?

Molds are microscopic organisms called fungi, found virtually everywhere, indoors and out. Molds reproduce through spores spread by water, insects or air. They are so tiny and lightweight they can float through the air like pollen. An allergy to mold is really a mold spore allergy.

What are mold allergy symptoms?

When inhaled, symptoms and signs of mold allergy include:

  • nasal and sinus congestion
  • sore throat
  • sneezing
  • watery or burning eyes
  • dry cough
  • shortness of breath
  • irritation of the nose, throat or even skin

What about mold and asthma?

What makes mold spores so harmful to people with asthma is mostly a mystery. Some experts say the small size of mold spores allows them to pass more easily into the lower airways, where they can trigger an asthma attack. Others contend mold spores may also interact with other allergens and environmental air pollution, thus increasing the asthma risk from those substances. In addition to mold allergy, people also can have an irritant response to some of the volatile chemicals that molds release into the air.

How to diagnose a mold allergy?

To test for a mold allergy, the doctor will take a comprehensive medical history and ask you about your symptoms and when they occur. Mold allergy tests include:

  • Skin prick tests – Droplets of mold allergens are placed on the skin surface with tiny punctures. Raised bumps (about the size of a mosquito bite) strongly indicate an allergy to that substance.
  • Blood tests – Chemical testing detects Immunoglobulin E (IgE) antibodies circulating in your blood that are directed at specific allergens. Lab results may take days. A blood sample is sent to a medical laboratory, where it can be tested for evidence of sensitivity to specific types of mold.

The doctor will put all the evidence together – test results, your personal and family health history, home and work environments, activities that might expose you to allergens, a physical exam of your eyes, ears, nose and lungs – before reaching a diagnosis.

Can you have an allergy to indoor and outdoor mold?

Yes, you can have an indoor mold allergy or outdoor mold allergy – or both. If you are allergic to mold, you will need to learn where mold grows and how to avoid it.

Outdoor mold 

Outdoor mold grows in dark, damp places and is found under fallen leaves and in rotting vegetation in gardens. The peak season for mold differs in different parts of the country:

  • Northern United States: Growth begins after the first spring thaw and peaks in late summer and fall
  • Southern United States: Year-round growth
  • Western United States: Year-round growth

Indoor mold 

Indoor mold can grow on any organic surface and is found in damp areas such as:

  • basements
  • attics
  • under-sink cabinets
  • refrigerators
  • garbage containers
  • washing machines and clothes dryers
  • upholstery and house plants
  • dusty and musty old books, magazines and newspapers
  • damp window moldings and sills
  • shower stalls and shower curtains

Mold can become a significant problem if it remains undiscovered or unaddressed. Allergy symptoms can occur when mold is inhaled.

How do you limit mold exposure?

Reducing mold inside your home

To reduce mold inside your home, eliminate the conditions they need to grow:

  • moisture
  • darkness
  • poor ventilation

How can you remove mold?

Mold is often difficult to remove in the home. It can even lurk inside walls. It’s best if someone other than the person with the mold allergy works to remove the mold.

First, identify the source of the moisture that is allowing the mole to grow and fix the source if you can. Remove any carpet or drywall that has had mold growing on it. If the mold is extensive, you may need to hire a mold remediation contractor.

If materials cannot be removed, you can remove visible mold and mildew with a household bleach solution or non-toxic mix of 1 tablespoon baking soda, 2 tablespoons white vinegar and 1 quart water.

Following cleaning, a dehumidifier is often useful in not allowing mold to regrow.

Reducing mold exposure outdoors

Outdoors, mold grows on leaves, trees and rotting wood. While ridding the outdoors of mold isn’t possible, you can reduce your exposure by keeping windows closed and limiting outdoor activities when mold levels are high.

Many local weather reports list mold counts along with pollution levels. Airborne molds often reach peak levels on dry, windy days when breezes kick up spores growing in moist areas.

How do you treat a mold allergy?

Mold allergy treatments include over-the-counter antihistamines and decongestants. These common allergy medications can relieve symptoms of runny nose, itchy and watery eyes and congestion.

It may be best to take these medications in advance when you know you may be around mold spores. Before starting any medication, speak with your doctor or allergist.

You may want to wear a mask when you know you’re going to be around mold. This will help prevent you from breathing in mold spores. If you are exposed to mold, you can remove them by rinsing your nose with a saline spray or taking a shower.

Immunotherapy, designed to make your body less reactive to an allergen over time, is available for certain types of mold, according to the American College of Allergy, Asthma & Immunology (ACAAI). Talk with an allergist for more information.

Ask the Allergist: Addressing Mold after Major Flooding

Are there other conditions that can look like or complicate allergies

There are other types of conditions that can mimic allergies, but are different than an IgE-mediated allergy. The symptoms, diagnosis and treatment can vary depending upon the condition. Here are some of them.

Food-related conditions that can have symptoms similar to food allergies include:

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