Mold Spores Allergy – Symptoms and Treatment

What is Mold?

Molds (in British English = moulds) are a type of multi-cellular fungi (as opposed to yeasts that are single-cell fungi). Molds are widely present in nature – they break down organic substances. Mildew is a type of fungi that appear on plants (outdoor and indoor). The term mildew is often used for any mold growth. Molds are found throughout the globe but tend to thrive in hot and moist environments.

Overall mold is not a harmful substance. Humans are in constant contact with molds and small amuonts do not cause any problems. However, some people develop an immune hypersensitivity (allergy) to molds and specifically to the spores produced by molds. This triggers inflammation and a host of symptoms depending on the area of the body where this reaction occurs.

Mold Spores

Molds produce spores (a type of microscopic seed) that represents an inactive form of mold. It is able to withstand a host of harsh conditions and when the situation is favorable, these spores can germinate from which new molds may develop. It is usually mold spores that cause mold allergies, and not the molds themselves. However, the active mold form has to be present to form these spores. Therefore more spores are found in the region where there is extensive mold growth.

Outdoor Molds

Common molds appearing outdoors are Alternaria, and Cladosporium. Outdoor mold spores appear in the air during and after:

  • Windy conditions or storms
  • Cutting grass
  • Spreading mulch
  • Harvesting

Most people with mold allergies are not affected by these outdoor molds unless they make close contact with vegetation or spend long hours outdoors, as is the case with farmers and gardeners. However, even in these cases the spores may be rapidly dissipated outdoors in contrast to closed environments indoors.

Indoor Molds

Common indoor molds are Aspergillus and Penicillium. Furthermore spores of outdoor molds may enter buildings through the air or when carried on clothing. Indoor mold spores commonly appear in the house dust as well. Any activity that raises dust from the floor may result in spores becoming airborne within the indoor air, especially when:

  • Sweeping and cleaning.
  • Changing bed linen.
  • Aerating the house.

When spores land on moist indoor surfaces, like walls, furniture, carpets, paper, clothes, or food, they develop into active forms. These grow as white, yellow, green, reddish, grey, or black, smooth or furry patches. It tends to prefer warm, moist and dark conditions. Therefore it may be widely found within closets and cupboards. However, if there is sufficient moisture in the air and warmth, it may grow on walls, ceilings and other surfaces.

What are Mold Allergies?

In sensitive people, mold spores when inhaled for the first time can trigger production of IgE antibodies in the eye conjunctiva, or nose, throat, or bronchial mucosa. During the subsequent inhalations of spores, IgE antibodies bind on mast cells in mucosa, and trigger release of a histamine which is a substances that causes inflammation. It usually causes the following symptoms:

  • Watery and itching eyes
  • Sneezing and runny nose
  • Cough
  • Wheezing
  • Shortness of breath (in asthmatics)

Symptoms in asthma may be quite severe, but deaths from mold allergy are extremely rare. It is important to note that the mold spores are just the trigger and not the cause of the disease.

Diagnosis of Mold Allergy

The presence of an allergy may be suspected from the symptoms and confirmed with positive blood tests, like increased amount of eosinophils (special type of white cells), and IgE antibodies. Blood tests may only serve to confirm an allergic reaction but do not always conclusively identify the trigger (allergen). A more accurate way of determining the allergen is to do a skin prick test. Minute amounts of common allergens are injected into the skin and if there is a positive reaction then it is conclusive for an allergy to that specific substance.

Treatment of Mold Allergy

Symptoms may be reduced with antihistamines that are taken orally. It can be used only when the symptoms appear or may be administered on a regular basis to prevent episodes.  Corticosteroids may also be prescribed on a chronic basis to reduce inflammation and prevent attacks. In some cases, treatment of an allergy itself is possible with immunotherapy. Increasing amounts of allergens are injected into the blood over period of several weeks, what often helps to reduce symptoms of allergy.

Who is at Risk of a Mold Allergy?

Some people are at a greater risk of developing allergies and not just a mold allergy. These risk factors include:

  • Mold allergy in family. If one family member has a mold allergy, other family members are at increased risk to get it also.
  • Occupations with high exposure to mold: farming, baking, mill-work, carpentry, greenhouse work, wine-making, and furniture repair.
  • Living in a moist house. Molds readily thrive in houses with moistness above 50%.
  • Working with uncovered stored food. Molds may appear in few days on bread and fruits.

Any person can develop a mold allergy but it is more likely to occur in people with atopy. These people tend to have a history of allergic rhinitis (hay fever), asthma or atopic dermatitis from early life. Allergies can develop later in life even without an allergic history from earlier in life.

Prevention of Mold Allergy

To prevent a reaction as a result of a mold allergy, a sensitive person should:

  • Avoid being present in environments where there is mold and a high spore count.
  • Avoid house dust that commonly contain mold spores. Spores can survive in a house dust for long periods, since they are highly resistant to low and high temperatures and pressure.
  • Prevent or eradicate mold in living environment by improving ventilation, scraping off mold and painting the area after waterproofing.

Other buildings commonly affected are stores, granaries, car washes, swimming pools, and other moist places. Although these places cannot be avoided entirely, a person should minimize exposure as far as possible. The duration of exposure plays a role in triggering an allergy. Therefore it is more likely to be a problem when there is mold within the home environment, and particularly when mold is in rooms like the bedroom.


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