If you have a mold allergy, your immune system overreacts when you breathe in mold spores. A mold allergy can cause coughing, itchy eyes and other symptoms that make you miserable. In some people, a mold allergy is linked to asthma and exposure causes restricted breathing and other airway symptoms.
If you have a mold allergy, the best defense is to reduce your exposure to the types of mold that cause your reaction. Medications can help keep mold allergy reactions under control.
A mold allergy causes the same signs and symptoms that occur in other types of upper respiratory allergies. Signs and symptoms of allergic rhinitis caused by a mold allergy can include:
- Runny or stuffy nose
- Cough and postnasal drip
- Itchy eyes, nose and throat
- Watery eyes
- Dry, scaly skin
Mold allergy symptoms vary from person to person and range from mild to severe. You might have year-round symptoms or symptoms that flare up only during certain times of the year. You might notice symptoms when the weather is damp or when you're in indoor or outdoor spaces that have high concentrations of mold.
Mold allergy and asthma
If you have a mold allergy and asthma, your asthma symptoms can be triggered by exposure to mold spores. In some people, exposure to certain molds can cause a severe asthma attack. Signs and symptoms of asthma include:
- Shortness of breath
- Chest tightness
When to see a doctor
If you have a stuffy nose, sneezing, watery eyes, shortness of breath, wheezing or other bothersome symptoms that persist, see your doctor.
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Like any allergy, mold allergy symptoms are triggered by an overly sensitive immune system response. When you inhale tiny, airborne mold spores, your body recognizes them as foreign invaders and develops allergy-causing antibodies to fight them.
Exposure to mold spores can cause a reaction right away, or the reaction can be delayed.
Various molds are common indoors and outdoors. Only certain kinds of mold cause allergies. Being allergic to one type of mold doesn't mean you'll be allergic to another. Some of the most common molds that cause allergies include alternaria, aspergillus, cladosporium and penicillium.
A number of factors can make you more likely to develop a mold allergy or worsen your mold allergy symptoms, including:
- Having a family history of allergies. If allergies and asthma run in your family, you're more likely to develop a mold allergy.
- Working in an occupation that exposes you to mold. Occupations where mold exposure can be high include farming, dairy work, logging, baking, millwork, carpentry, greenhouse work, winemaking and furniture repair.
Living in a house with high humidity. Having indoor humidity higher than 50% can increase mold in your home.
Mold can grow virtually anywhere if the conditions are right — in basements, behind walls in framing, on soap-coated grout and other damp surfaces, in carpet pads, and in the carpet itself. Exposure to high levels of household mold can trigger mold allergy symptoms.
- Working or living in a building that's been exposed to excess moisture. Examples include leaky pipes, water seepage during rainstorms and flood damage. At some point, nearly every building has some kind of excessive moisture, which can encourage mold growth.
- Living in a house with poor ventilation. Tight window and door seals can trap moisture indoors and prevent proper ventilation, creating ideal conditions for mold growth. Damp areas — such as bathrooms, kitchens and basements — are most vulnerable.
Most allergic responses to mold involve hay fever-type symptoms that can make you miserable but aren't serious. However, certain allergic conditions caused by mold are more severe. These include:
- Mold-induced asthma. In people allergic to mold, breathing in spores can trigger an asthma flare-up. If you have a mold allergy and asthma, be sure that you have an emergency plan in case of a severe asthma attack.
- Allergic fungal sinusitis. This results from an inflammatory reaction to fungus in the sinuses.
- Allergic bronchopulmonary aspergillosis. This reaction to fungus in the lungs can occur in people with asthma or cystic fibrosis.
- Hypersensitivity pneumonitis. This rare condition occurs when exposure to airborne particles such as mold spores causes lung inflammation. It can be triggered by exposure to allergy-causing dust at work.
Other problems caused by mold
Besides allergens, mold can pose other health risks to susceptible people. For example, mold can cause infections of the skin or mucous membranes. Generally, however, mold doesn't cause systemic infections except for people with impaired immune systems, such as those who have HIV/AIDS or who are taking immunosuppressant medication.
To reduce mold growth in your home, consider these tips:
- Eliminate sources of dampness in basements, such as pipe leaks or groundwater seepage.
- Use a dehumidifier in any area of your home that smells musty or damp. Keep your humidity levels below 50%. Remember to clean the collection bucket and condensation coils regularly.
- Use an air conditioner and consider installing central air conditioning with a high-efficiency particulate air (HEPA) filter attachment. The HEPA filter can trap mold spores from outdoor air before they're circulated inside your home.
- Change filters on your furnace and air conditioners regularly. Have forced air heating ducts inspected and, if necessary, cleaned.
- Be sure all bathrooms are properly ventilated, and run the ventilation fan during a shower or bath and immediately after to dry the air. If you don't have a ventilation fan, open a window or door while you're showering or bathing.
- Don't carpet bathrooms and basements.
- Promote groundwater drainage away from your house by removing leaves and vegetation from around the foundation and cleaning out rain gutters frequently. Make sure the ground slopes away from the foundation.
- Keep organic plant containers clean and dry, such as those made of straw, wicker or hemp.
- Toss or recycle old books and newspapers. If left in damp places, such as basements, they can quickly become moldy.
Jun 21, 2021
- Mold allergy. American Academy of Allergy, Asthma & Immunology. https://www.aaaai.org/conditions-and-treatments/allergies/mold-allergy. Accessed Feb. 17, 2021.
- Mold allergy. Asthma and Allergy Foundation of America. https://www.aafa.org/mold-allergy/. Accessed Feb. 17, 2021.
- A brief guide to mold, moisture and your home. Environmental Protection Agency. https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home. Accessed Feb. 17, 2021.
- DeShazo RD, et al. Pharmacotherapy of allergic rhinitis. https://www.uptodate.com/contents/search. Accessed Feb. 17, 2021.
- Ahasic AM, et al. Building-related illness and building-related symptoms. https://www.uptodate.com/contents/search. Accessed Feb. 17, 2021.
- Basic facts about mold and dampness. Centers for Disease Control and Prevention. https://www.cdc.gov/mold/faqs.htm. Accessed Feb. 19, 2021.
- Sultesz M, et al. Prevalence of allergic rhinitis, related comorbidities and risk factors in schoolchildren. Allergy, Asthma & Clinical Immunology. 2020; doi: 10.1186/s13223-020-00495-1.