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Everything You Need to Know About Indoor Allergies


Indoor allergies are allergies that are triggered by allergens commonly found in the home or other indoor locations. Common indoor allergies include mold, dust mites, pet dander, and even cockroaches. Indoor allergies may be less seasonal and more difficult to avoid than allergies to outdoor substances, and they can be just as debilitating.


Allergic reactions occur when your immune system becomes overly sensitive to certain substances (called allergens). Your immune system will then release chemical mediators such as histamine in response to the allergen.1

These substances cause symptoms. Blocking histamine with medications called antihistamines can alleviate symptoms. It is not always possible to identify why some individuals' immune systems overreact, but allergies may be hereditary.2

Indoor allergies are also strongly associated with asthma, a long-term disease of the lungs causing the airways to narrow and restrict breathing.3

Most Common Indoor Allergies

Dust Mites

Dust mites are tiny arthropods that can only be seen with a microscope. They feed off of tiny flakes of shed human skin and can be found in furniture, carpeting, bedding, and plush toys. Mites prefer warm and humid environments.4

Specific ways you can reduce dust mites in your home include:

Reducing humidity

Frequently vacuuming with a vacuum that has a certified filter

Placing dustproof covers over mattresses and pillows

Washing your bedding in hot water at least weekly

Reducing the amount of carpeting (and rugs) in your home

Using specialized filters on your central air-conditioner

Animal Dander

Some people are allergic to proteins found on animal fur, skin, saliva, or urine. Symptoms of animal dander allergies are similar to the other indoor allergies.

Specific ways you can reduce animal dander in your home include:5

Keeping pets out of your bedroom or sleeping area

Keeping pets off of your furniture as much as possible

Having someone who is not allergic regularly brush and groom your pet outdoors

Frequently vacuuming with a vacuum that has a certified filter

Limiting the amount of carpeting (and rugs) in your home


Mold and fungi reproduce and grow through spores that are released into the air and then inhaled, causing an allergic reaction.

You can be allergic to both indoor and outdoor molds.

Indoor mold allergies can cause year-round symptoms. In the home, the most likely places to encounter these spores are areas that are prone to dampness or water damage, such as the kitchen or bathroom.

You can reduce mold spores in your home by:6

Adding a certified filter to the central heating and air-conditioning unit in your home

Lowering the humidity in your home

Reducing dampness in your home, such as by cleaning up spilled water and fixing plumbing leaks

Using exhaust fans and ventilating your home by opening doors and windows

Not allowing laundry, bedding, or carpets to remain wet or damp


Cockroaches are common in many parts of the world, especially in warmer climates.

The body parts, saliva, and droppings from cockroaches contain proteins that some people are allergic to. Cockroach allergies are known for triggering asthma attacks.

Some steps you can take to reduce this allergen in your home include:7

Put a tight lid on all of your garbage cans.

Do not leave dirty dishes or pet bowls out.

Be proactive in cleaning up any crumbs or bits of food from your floors or other areas of your home.

Clean up water spills and fix plumbing issues promptly, as dampness may attract cockroaches.

Use bait and traps or hire an exterminator to control the number of cockroaches in your home.

Seal cracks in your walls and floors, which may allow the bugs to enter your home.

Store food in containers that cannot be accessed by bugs.


Regardless of the culprit, most indoor allergies cause similar symptoms. They also tend to be a problem year-round rather than at certain times of the year, like seasonal or weather-related allergies.

Common Indoor Allergy Symptoms

Some common symptoms of indoor allergies include:3


Runny nose


Itchy eyes or throat

Hives or skin rashes



More severe symptoms of indoor allergies include:


Shortness of breath

Severe and frequent sinusitis

Malaise (general feeling of being unwell)


An immunologist (a doctor who specializes in the diagnosis and treatment of allergies) can diagnose allergies.

In addition to a review of your symptoms and a physical examination, the following tests are commonly used to diagnose allergies:

IgE (immunoglobulin E) antibody testing

Skin scratch or skin prick testing, in which a small amount of a suspected allergen is inserted into the skin to see if it causes a reaction

When to Seek Treatment

You should consult a healthcare provider anytime you have had bothersome or unrelieved symptoms lasting longer than a few weeks. You should go to the emergency room or call 911 if you have difficulty breathing or feel like your throat is swelling or closing. This is a symptom of a life-threatening allergic reaction known as anaphylaxis.


Treatment for indoor allergies usually involves a combination of medication and measures to reduce your exposure to the allergen.

The following medications are common for the treatment of indoor allergies:

Nonsedating antihistamines, such as Zyrtec (cetirizine) or Allegra (fexofenadine)

Sedating antihistamines like Benadryl (diphenhydramine), which can be used if allergy symptoms are interfering with sleep (but are not preferred for long-term use and should be used with caution in patients at risk for falls)

Nasal corticosteroids, such as Advair or Flonase (fluticasone), Qvar (beclomethasone), or Entocort (budesonide)

Oral or nasal decongestants, such as Sudafed (pseudoephedrine) or Afrin (oxymetazoline), which can be used for a few days for symptoms that are not relieved by antihistamines and/or nasal corticosteroids (but should not be used long-term due to side effects)

Leukotriene receptor antagonists, such as Singulair (montelukast), which are sometimes prescribed for symptoms that are not relieved with the above therapies. They are not first-line agents, and patients should be aware of the black box warning for neurological and psychiatric adverse events that can occur in some patients who take Singulair.

Avoiding triggers (substances that bring on an allergy) is an important part of treatment. Common ways of controlling indoor allergies include adequate housecleaning, proper ventilation, air purifiers, humidity control and pest control (for cockroaches), and repairing broken pipes or water damage.8


In some cases, your allergy symptoms may be reduced or cured through immunotherapy. Immunotherapy usually comes in the form of an allergy shot, but recently sublingual (under the tongue) versions have become available for some types of allergies.

Immunotherapy works by exposing you to a small amount of the substance you are allergic to over a long period of time. This should help desensitize your immune system. Immunotherapy must be administered under the supervision of your healthcare provider and can involve a significant time commitment.