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Mold Inspection and Testing

Common Molds That You May Be Allergic To

Americans are regularly exposed to dozens of different mold species, both outside and within buildings. Not all molds pose a risk to human health, but those that do fall into different categories. Some molds are toxic or pathogenic, while others are allergenic.

Not everyone who encounters molds with a high allergenic potential will suffer allergy symptoms — the CDC has estimated that between six and 10 percent of Americans are sensitive to mold allergens. That does not mean that you can sit back and relax if you know that a mold infestation is present in your home but you have not experienced any allergy-related symptoms so far, however. Prolonged exposure will cause you to become sensitized to allergenic molds over time, and at that point, allergy symptoms kick in.

How can you tell whether you may be allergic to mold, and what types of mold are most likely to be a problem?

Who Can Reasonably Suspect They Are Experiencing a Mold Allergy?

The symptoms of a mold allergy are identical to the symptoms of other common allergies, including hay fever, and they include:

  • Respiratory symptoms like a runny and itchy nose, nasal congestion, sneezing, wheezing, coughing, a hoarse voice, and even shortness of breath.
  • Watery, swollen, red, and itchy eyes.
  • Skin-related symptoms that can include redness and itching, as well as hives — pronounced and very itchy red patches that may appear all over the body.
  • Systemic symptoms such as diarrhea, stomach pain, a headache (or “foggy feeling”), fatigue, and general feelings of malaise.

We all routinely come into contact with different types of mold spores. While many molds won’t trigger allergic symptoms, some mold species instant cause noticeable discomfort in people with allergies.

Outdoor molds tend to trigger allergy symptoms during the summer and fall, although your discomfort might last through the year in some places. As mold spores easily travel through the air, carried by wind, there is not that much you can do to avoid exposure to molds in the environment.

Indoor molds are, however, a different matter. Even if you already know that you suffer from seasonal allergies, you would be right to suspect that you could also have a mold allergy if those tell-tale allergy symptoms worsen when you’re at home, at work, or in someone else’s residence throughout the year — even when allergy season is over in your area. Indoor molds thrive in damp conditions and produce spores constantly. Do you suddenly start feeling “chesty” the moment you enter your humid basement, for instance? Although only a doctor can diagnose a mold allergy, that certainly offers you enough of a clue to consult an allergist!

How Is a Mold Allergy Diagnosed?

Mold allergies are diagnosed with the help of skin or blood tests that measure your levels of IgE (Immunoglobulin E) in reaction to certain types of mold. Such diagnostic tests tell you with great certainty what types of mold you react most strongly to. This can especially be helpful for people who know that they’re allergic to something, but who have never identified the cause of their allergy symptoms. Broadly speaking, of course, knowing that you are allergic to any type of mold should make combating any mold infestation on your property — where you spend so much of your time — a top priority.

What Types of Mold Are People Frequently Allergic To?

Because not all mold species thrive in the same conditions, learning what types of mold tend to cause allergic reactions — and understanding where these molds generally lurk within homes — can help you take steps to reduce your symptoms.


This mold family has at hundreds of distinct members, and is so prolific that it is impossible to avoid altogether; even if your home does not have a mold problem, you will encounter Aspergillus outdoors. Inside your property, however, it is most commonly found around decaying plant matter. Similar organic substances like clothing, curtains, and leather upholstery are also hospitable environments for this mold. Because the spores of Aspergillus molds will be released into the air in higher concentrations when the mold growth is interfered with, allergy symptoms often get worse after you vacuum, clean, or move your house plants.

Some types of Aspergillus also have the potential to cause serious infections — even in people who are not allergic. Aspergillus fumigatus is the worst offender, and it poses a particular threat to those with compromised immune systems.


Another prolific set of mold species, Cladosporium is one of the most frequent sources of indoor mold infestations. Growing in characteristic darkly-colored colonies, these molds tend to live on both dead and live plant matter, where they may colonize other molds species. You may find Cladosporium on plants and in compost heaps, but these molds are also very frequently located on bathroom walls and within other humid spaces.

Although many Cladosporium molds are relatively harmless to most people, those with mold allergies may immediately begin suffering from breathlessness and chest tightness when they enter a space containing high concentrations of these molds. Cladosporium molds are also a well-known trigger for asthma attacks.


This name is, of course, familiar to you — and you may have heard a relative jokingly refer to mold that grows on old bread or fruit as “natural penicillin”. Indeed, some members of this large mold family produce penicillin, an antibiotic that has saved countless lives. Others can lead to dangerous health complications, on the other hand, including Penicillium aiurantiorisen.

Penicillium molds are strongly associated with spoiled foods, but these green, white, and blue molds can also take over your kitchen, thrive within fabrics, and accumulate deep within your walls.


Over 250 different Alternaria molds can be found both outdoors and indoors. Highly airborne, Alternaria species pose a huge threat to agricultural ventures, especially in warmer and more humid climate conditions. They may enter your home from outside, and build up within your HVAC system. Alternaria molds also easily settle within carpets, on wallpaper, and around windows.


This mold family may have fever members, at around 50 species, but it is extremely widespread — and even though you might have trouble pronouncing the name Stachybotrys, you will certainly have heard of this type of mold before. Stachybotrys chartarum is the most infamous Stachybotrys mold, and these species are more commonly simply called “black mold”.

Stachybotrys molds thrive in seriously wet conditions, as they require constant access to water. That is why they are common in composting systems, but homes with significant water damage — especially leaky plumbing — may also develop infestations. These molds may not only trigger severe allergy symptoms in predisposed people, they have also been associated with serious health complications in infants and young children.

How Is a Mold Allergy Treated?

Yes, the symptoms of a mold allergy can, to some extent, be managed with medications that include antihistamines and steroid sprays. Yes, managing your symptoms with medications offers relief, especially given the fact that environmental mold exposure is inevitable.

The primary — and most successful — way to treat a mold allergy is to reduce your exposure to the allergen, however. That is why the Allergy and Asthma Foundation of America recommends medication almost as an afterthought. If you have a mold infestation within your home, it is imperative to tackle the root of the problem.

As someone who has been diagnosed with a mold allergy, or who suspects a mold allergy, the main weapons at your disposal would include:

  • Reducing humidity levels within your home, including fixing plumbing problems and dealing with leaky gutters.
  • Increasing ventilation.
  • Installing a HEPA air purifying system to filter out the mold spores that do enter your home.

Now That You’ve Been Diagnosed with a Mold Allergy, Does Your Home Need Testing?

You can be certain that you are dealing with a mold infestation in your home if you can see mold, and you can have great confidence in self-diagnosing a mold problem if you recognize the heavy smell of mold, too. Because a wide variety of mold species, including those we have examined here, can indeed build up in places that you may not notice, however, only a professional mold inspector can inform you of the extent of a mold problem within your home.

When MI&T, a long-standing and reputable mold inspection only company, performs a full inspection of your property, the air samples we take in the process leave no doubt about the types of mold within your home. Knowing what types of mold you are dealing with, and where the source of the infestation lies, enables you to take steps to remediate your mold infestation.

Maybe you have hired a mold remediation company to deal with a mold problem already, but you are still experiencing the symptoms of a mold allergy. In that case, MI&T’s unbiased and independent clearance testing lets you know whether your home still needs further attention.

Once you have the full picture, you will know exactly what you need to do to eliminate mold from your home — so that you can finally breathe easy.