Mold is a type of fungal growth that produces spores. Exposure to these spores may cause allergy symptoms, as the spores sometimes trigger an immune response when people inhale them.

Minimizing exposure to mold is the best way to avoid symptoms, but medications can also help.

This article discusses mold and the symptoms, causes, and treatment of a mold allergy. It also outlines some health considerations and answers some common questions about mold allergies.

To discover more evidence-based information and resources for asthma & allergies, visit our dedicated hub.

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Mold is a type of fungus that develops on organic matter that is either damp or rotting. There are different species of mold, which can grow indoors or outdoors.

Mold spores are present in even the cleanest of environments, which means that everyone experiences exposure to mold at some point in their life.

Although molds themselves are not toxic, certain types can be toxigenic. This means that they create spores or cell fragments that produce toxins. They can also produce inflammatory substances and allergens. Research indicates that mold or damp exposure in childhood can increase a person’s risk of developing asthma and allergies.

People sometimes refer to mold as mildew. However, the terms are not interchangeable, as mildew only refers to specific types of mold, whereas mold is a more generic term.

Mold can cause symptoms of allergy and asthma, although the exact symptoms vary slightly depending on the individual immune response.

Common types of mold that may cause allergy symptoms include:

Allergy symptoms typically occur when mold spores get into a person’s nose or throat, whereas asthma symptoms occur when spores pass down into the lungs. In both cases, the immune system identifies the mold spores as allergens and responds accordingly by triggering symptoms.

Mold allergy symptoms can include:

Mold may also cause asthma symptoms, including:

Allergy symptoms from mold spores are most common from the start of summer to the start of fall, although they can occur at any point in the year.

The main cause of indoor mold is usually excessive dampness. The mold spreads to other areas through the spores it produces, which break off and travel through the air. As they land, they form new mold colonies, increasing the mold cover indoors.

Molds are everywhere, but they thrive in moderate temperatures and damp environments, particularly when there is organic matter on which they can grow.

Mold causes symptoms when people with a mold allergy inhale the spores, enabling them to enter the nose and throat.

It is not always possible to avoid sources of mold spores. However, if possible, minimizing exposure to mold is the best way to reduce symptoms.

A person can avoid outdoor mold spores by checking mold counts within their local area and staying indoors on days when the counts are high. If they need to go out, showering afterward can remove mold spores from the hair and skin, which may reduce the likelihood of outdoor mold spores causing symptoms.

Avoiding indoor mold spores can be more challenging, particularly if a person lives in a warm, damp environment. People can reduce dampness by fixing any pipe leaks or other causes of dampness as soon as they appear. A dehumidifier may be useful, as it is best to keep humidity levels below 60% if possible.

Vinegar contains acidic properties that make it an effective cleaner when removing mold patches from walls.

As well as avoiding mold, a person may take medications to manage a mold allergy. Antihistamines and corticosteroid medications, which are available over the counter, may help with allergy symptoms.

A person should check with a healthcare professional before taking any new medication.

If the symptoms persist, a doctor may recommend immunotherapy shots. These are regular injections that reduce allergy symptoms by exposing the body to small doses of the mold that is causing symptoms. This enables the immune system to build up a natural defense, which it applies when there is exposure to mold on a larger scale.

In some cases, mold exposure can cause severe reactions. For example, allergic alveolitis, which is a serious lung disease, may result from mold exposure and humidifiers containing spores. Allergic bronchopulmonary aspergillosis is another severe lung condition that can occur after exposure to mold.

Studies indicate that atopic diseases, including asthma and rhinitis, may develop following exposure to mold during the early years of childhood.

Despite the potential for a severe reaction, known as anaphylaxis, this typically only occurs when a person has exposure to high amounts of mold or when humidifiers or air ducts have mold contamination, resulting in additional spores passing through the air.

In previous years, there has been an emphasis on the toxicity of mold. However, more recent research suggests that the risks of mold inhalation typically decrease during the adolescent years.

Anaphylaxis is a severe allergic reaction that can be life threatening. The symptoms develop suddenly and include:

  • hives
  • swelling of the face or mouth
  • wheezing
  • fast, shallow breathing
  • a fast heart rate
  • clammy skin
  • anxiety or confusion
  • dizziness
  • vomiting
  • blue or white lips
  • fainting or loss of consciousness

If someone has these symptoms:

  1. Check whether they are carrying an epinephrine pen. If they are, follow the instructions on the side of the pen to use it.
  2. Dial 911 or the number of the nearest emergency department.
  3. Lay the person down from a standing position. If they have vomited, turn them onto their side.
  4. Stay with them until the emergency services arrive.

Some people may need more than one epinephrine injection. If the symptoms do not improve in 5–15 minutes, or they come back, use a second pen if the person has one.

Below are the answers to some of the most common questions about mold allergies.

Is it possible to treat a mold allergy?

The best way to prevent symptoms is to avoid exposure to mold as far as possible. However, medications such as antihistamines and corticosteroids can help reduce the symptoms.

What are the symptoms of mold exposure?

The symptoms of mold exposure may include:

  • blocked nose
  • wheezing
  • red and itchy eyes
  • itchy, discolored skin

Do air purifiers help with mold?

Yes, research indicates that an indoor air purifier can help by reducing molds and bacteria in the air.

Mold is a fungal growth that can develop in indoor and outdoor spaces. It produces spores and cell fragments that travel through the air and form new colonies on damp and organic surfaces.

There are many different types of mold. Some cause symptoms, but others do not. The main mold groups that can cause allergy symptoms are Alternaria, Aspergillus, Penicillium, and Cladosporium.

The visible mold colonies do not cause symptoms directly, but the spores they produce may carry toxins. These spores trigger an immune response in some people as they enter the nose and throat. This response is an allergic reaction.

Avoiding mold as much as possible is the main way of avoiding mold allergy symptoms. However, this is not always possible, as mold spores are present in most environments.

A doctor may recommend taking medication to manage allergy symptoms. The options may include antihistamines and corticosteroids or immunotherapy.