Skip to content

Allergens and Symptoms


An allergen is a substance –such as dust, pollen or mold—that causes an allergic reaction in some people. Inhalant allergens include pollens, molds, dust and animal dander. We do not test for food or chemical allergens. Following is some useful information about the most common types of allergens, their symptoms, and how you can reduce your exposure to them.

Environmental Control

Typically, the first line of defense against allergens is to avoid them as much as possible. This reduces your “total load.” Every airborne and ingested allergen, as well as irritants (such as perfumes, tobacco smoke, or chemicals), adds to what we call your total load, or total exposure. For this reason, we often recommend making changes that can reduce their exposure to allergens, if applicable. Since most people spend up to 90% of their time indoors, look for allergens in the areas in your work, home, or other environments where you spend most of your time.


Trees, weeds, flowers, shrubs, and grasses produce pollen grains. The male pollen grain cells are carried by insects or by the wind to female cells for fertilization. Approximately a quarter of a million plants use the wind to transport clouds of pollen grains in the pollination process. Pollen counts vary by season and by area of the country. Ragweed produces a large amount of pollen and causes many people significant discomfort.

Not all plants are sources of allergenic pollen. To be considered a common allergic source, plants must typically:

  • Be seed-bearing, with pollen wind-borne for wide distribution.
  • Produce pollen in large quantities
  • Have buoyant pollen that can be distributed over a wide area.
  • Be widely and abundantly distributed, preferably close to human habitation.
  • Produce allergenic pollen

Symptoms of an allergic reaction to pollens include:

  • Itchy, watery, red eyes
  • Thin/clear nasal discharge
  • Sneezing
  • Dry, hacking cough
  • Nasal itching

Preventing pollen exposure is not as simple as staying indoors. While staying indoors does help, it does not completely eliminate pollen exposure. Remember that pollen can be carried indoors on shoes, pets or clothing. You can reduce your “total load” of pollen exposure by:

  • Keeping windows and doors closed as much as possible
  • Wearing a mask when participating in outdoor activities
  • Bathing pets frequently
  • Taking a shower after being outside during days with high pollen levels
  • Refraining from bringing cut flowers or dried weeds into the house

You can find updated information on the pollen count in your area by clicking here


Molds or mildew can include a variety of fungi, such as mushrooms, yeasts, rusts, and smuts. However, in relation to allergens, “mold” usually refers to fungi that appear as woolly or powdery growths on stored fruits, or fungi that grow in damp areas of the home (such as bathrooms). Because molds thrive in warm, dark, moist areas, they can be found in several common areas, such as:

  • Garden areas or compost piles
  • Moist surfaces in the basement, bathroom or kitchen
  • Areas affected by roof or plumbing leaks
  • Deteriorating carpet
  • Drapery or upholstery
  • Garbage cans or trash compactors
  • Worn clothes—particularly leather
  • Kitty litter
  • Poorly ventilated closets
  • Inefficient air filters, which in turn allow mold and dirt to accumulate on coils, drain pans and duct work

Symptoms of an allergic reaction to molds include:

  • Wet cough
  • Chronic sinusitis
  • Eustachian tube dysfunction (the tube that links the middle ear to the base of the soft palate)
  • Headaches
  • Itchy skin and eyes
  • Pharyngitis (inflammation of the back of the throat)
  • Laryngitis (inflammation of the larynx or voice box)
  • Cloudy nasal discharge

It may be necessary to inspect your entire home for mold sources, and you may wish to have cultures completed to determine what molds are present and in what quantities Remove any visible mold with a stiff brush and treat area with mold retardant. Other helpful tips for eliminating or avoiding mold include:

  • Use high-performance filters on furnace.
  • Use a dehumidifier in the basement and a fan to dry areas.
  • Remove house plants, feather pillows.
  • Decrease the amount of mold-fermented foods in your diet (mushrooms, beer/wine, aged cheeses, etc.)

Dust mites

A dust mite is an eight-legged insect (arachnid) related to a spider. While the dust mite does not carry disease, it ingests human and animal skin scales. Actually, it is the dust mite’s feces—not the mite itself—that are the allergens. Because dust mites are so tiny, they can only be seen through a magnifying glass. Dust mites may be found in mattresses, couches, stuffed animals, bedding, pillows, and carpeting. They thrive in humid environments in temperatures between 68 and 84 degrees.

Symptoms of an allergy caused by the presence of dust mites include:

  • Sneezing
  • Clear/cloudy nasal discharge
  • Burning of the nasal passages
  • Nasal stuffiness
  • Chronic sinusitis
  • Cough
  • More symptoms present in the morning than in the evening

To reduce your exposure to dust mites:

  • Wash bedding in hot water weekly. Bedding may also be placed in a freezer for a day to kill dust mites or fluffed in a clothes dryer to remove dead mites.
  • Encase pillows and mattresses with zippered coverings
  • Damp dust whenever possible
  • Vacuum carpets with a high-performance vacuum.

Pet dander

Pet dander is microscopic flakes of skin shed by cats, dogs and other animals with fur or feathers. Dander can cause allergic reactions in some people. Pet dander travels on the animal and everything it touches. Because dander is very lightweight, it stays airborne even longer than pollen.

Symptoms of an allergic reaction to danders include:

  • Itchy nose
  • Itchiness on the roof of the mouth
  • Red/ watery eyes
  • Sneezing

To reduce your exposure to pet dander:

  • Keep pets outside or confine them to one area of your house
  • Bathe pets frequently
  • Wear a mask
  • After contact with pets, remove clothes in the laundry room, not the bedroom.
  • Vacuum frequently and ventilate the house whenever possible.