Mold allergy

Date Updated: 08/07/2025

Overview

If you have a mold allergy, your immune system is overly sensitive to mold spores. A mold allergy can cause coughing, itchy eyes and other symptoms that make you uncomfortable. In some people, a mold allergy is linked to asthma. If mold allergy is linked to asthma, mold exposure can cause 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. Medicines can help keep manage mold allergy reactions.

Symptoms

A mold allergy causes the same symptoms that happen in other types of upper respiratory allergies, such as hay fever. Symptoms caused by a mold allergy can include:

Sneezing.
Runny or stuffy nose.
Cough and postnasal drip.
Itchy eyes, nose and throat.
Watery eyes.
Dry, itchy 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. Symptoms of asthma include:

Coughing.
Wheezing.
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 a healthcare professional.

Causes

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 mildew, alternaria, aspergillus, cladosporium and penicillium.

Risk factors

A number of factors can make someone more likely to develop a mold allergy or make mold allergy symptoms worse, 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 a job 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 home 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 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 home 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 likely to have mold.

Complications

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 serious. 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.
Hypersensitivity pneumonitis. This rare condition happens when exposure to airborne particles such as mold spores causes lung inflammation. It can be triggered by exposure to allergy-causing dust at work.
Allergic bronchopulmonary aspergillosis. This reaction to fungus in the lungs can happen in people with weakened immune systems or lung conditions, such as asthma or cystic fibrosis.

Prevention

To reduce mold growth in your home, follow these tips:

Get rid of 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 filter attachment. This type of filter also is called a HEPA filter. 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.

Diagnosis

Besides considering symptoms, a healthcare professional might do a physical exam to look for or rule out other medical conditions. Tests used to diagnose an allergy include:

Skin prick test. This test uses diluted amounts of common or suspected allergens, such as molds found in the local area. During the test, these substances are put on the skin of your arm or back with tiny punctures. If you're allergic, you develop a raised bump called a hive at the test location on your skin.
Blood test. A blood test, sometimes called the radioallergosorbent test, can measure your immune system's response to mold by measuring the amount of antibodies in your bloodstream known as immunoglobulin E antibodies. A blood sample is sent to a medical lab, where it can be tested for evidence of sensitivity to specific types of mold.

Treatment

The best way to manage an allergy is to avoid exposure to triggers. However, molds are common and you can't completely avoid them.

While there's no sure way to cure symptoms caused by a mold allergy, several medicines can ease them. These include:

Nasal corticosteroids. These nasal sprays help prevent and treat the inflammation caused by an upper respiratory mold allergy. For many people, they're the most effective allergy medicines, and they're often the first medicines recommended.

Examples include ciclesonide (Omnaris), fluticasone (Flonase Allergy Relief, Xhance), mometasone (Nasonex 24HR Allergy), triamcinolone (Nasacort Allergy 24 Hour) and budesonide (Rhinocort). Nosebleeds and nasal dryness are the most common side effects of these medicines, which are generally safe for long-term use.
Antihistamines. These medicines can help with itching, sneezing and runny nose. They work by blocking histamine, an inflammatory chemical released by the immune system during an allergic reaction.

Antihistamines that you can buy without a prescription include loratadine (Alavert, Claritin), fexofenadine (Allegra Allergy) and cetirizine (Zyrtec Allergy). They cause little to no drowsiness or dry mouth.

The antihistamine nasal spray olopatadine is available by prescription. Azelastine is another antihistamine nasal spray and is available without a prescription (Astepro Allergy). Side effects of the nasal sprays can include a bitter taste in your mouth and nasal dryness.
Oral decongestants. Nonprescription oral decongestants, such as pseudoephedrine (Sudafed 12 Hour), can raise blood pressure, so avoid them if you have high blood pressure. Other possible side effects include insomnia, loss of appetite, heart pounding, anxiety and restlessness.
Decongestant nasal sprays. These include oxymetazoline (Afrin, others). Don't use these medicines for more than three or four days, as they can cause congestion to come back with worse symptoms. Other possible side effects include headache, insomnia and nervousness.
Montelukast (Singulair). Montelukast is a tablet taken to block the action of leukotrienes — immune system chemicals that cause allergy symptoms such as excess mucus. However, concerns about side effects, including anxiety, insomnia, depression and suicidal thinking, are increasing. The U.S. Food and Drug Administration recently added a boxed warning to the medicine's label.

Other treatments for mold allergy include:

Immunotherapy. This treatment — a series of allergy shots — can be very effective for some allergies, such as hay fever. Allergy shots are used for only certain types of mold allergy.
Nasal lavage. To help with irritating nasal symptoms, a healthcare professional might recommend that you rinse your nose daily with salt water. This home remedy, called nasal lavage, can help keep your nose free of irritants. Use a specially designed squeeze bottle — such as the one included in saline kits (Sinus Rinse, others) — a rubber-bulb syringe or a neti pot to irrigate your nasal passages.

Use water that's distilled, sterile, previously boiled and cooled, or filtered using a filter with an absolute pore size of 1 micron or smaller to make up the irrigation solution. Be sure to rinse the irrigation device after each use with similarly distilled, sterile, previously boiled and cooled, or filtered water and leave it open to air-dry.

Self care

To keep mold allergy symptoms at bay, take these measures:

Sleep with your windows closed to keep out outdoor mold. The concentration of airborne mold spores tends to be greatest at night, when the weather is cool and damp.
Keep indoor humidity below 50% and correct any moisture or water damage in the home. You can measure relative humidity with a small moisture meter, available at many hardware stores.
Wear a dust mask over your nose and mouth to keep out mold spores if you have to rake leaves, mow your lawn or work around compost.
Avoid going outdoors at certain times, such as right after a rainstorm, in foggy or damp weather, or when the published mold count is high.

Preparing for your appointment

Many people are diagnosed and treated for allergies by their primary healthcare professional. However, depending on how bad your allergies are, your health professional might refer you to a doctor who specializes in treating allergies.

Here's some information to help you get ready for your appointment.

What you can do

Ask if there are things you should do ahead of time when you make your appointment. For example, if you're having allergy tests, your healthcare professional will likely want you to stop taking allergy medicines for several days before the test.
Write down your symptoms, as well as where you were and what you were doing when the symptoms started.
List all the medicines, vitamins and other supplements you take, including doses.
Write down questions for your health professional.

For a mold allergy, some questions you might want to ask include:

What do you think is causing these symptoms?
Are there tests available that can confirm a specific allergy? Do I need to prepare for these tests?
How can I treat a mold allergy?
What side effects can I expect from allergy medicines?
How can I get mold out of my home?
I have another health condition. How can I best manage these conditions together?
Do you have brochures or other printed materials I can have? What websites do you recommend?

What to expect from your doctor

Your healthcare professional is likely to ask you questions, such as:

Exactly what are your symptoms?
What seems to trigger symptoms or worsen them?
Are your symptoms worse during certain times of the year or certain times of the day?
Do your symptoms flare up when you're in certain locations, such as outdoors or in your basement?
What other health conditions do you have?
Do other members of your family have allergies? What kinds?
Are you exposed to mold, dust, fumes or chemicals at work?
Do you know if you have mold in your home?

What you can do in the meantime

While you're waiting to see your doctor, there are numerous nonprescription allergy medicines that may ease your symptoms.

If you have visible mold in your home, have someone who's not allergic to mold clean the area using a commercially available mold-cleaning product or a solution of 1 cup (250 milliliters) of bleach to 1 gallon (3.8 liters) of water. If you have to clean up the mold yourself, be sure to wear long rubber gloves, safety goggles and a mask to limit your exposure to the mold.