Indoor Allergens (cont.)

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What about allergies to indoor pollens and houseplants?

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It is surprising, considering how frequently outdoor pollens cause allergies, that few indoor plants are troublesome. Indoor plants are more leafy than flowering and do not pollinate as much as outdoor plants. Some offending indoor plants are the weeping fig (Ficus benjamina), which can cause eye allergies, and the flowering maple (Alutilon hybridum), which can cause asthma.

Indoor plants, especially those that are kept in damp wicker baskets, are a source of molds. Plant terrariums and large indoor plants are culprits as well. Dried flowers and live Christmas trees should also be avoided, as they are common carriers of molds.

Table 1: Where Animal Allergens Come From
CatSkin, Saliva
DogSkin, Saliva
Guinea PigUrine, Saliva
RabbitUrine, Saliva
GerbilSkin, Serum

What is the treatment for allergic reactions to indoor allergens?

Avoidance of identified indoor allergens can be very effective in controlling allergy symptoms. If such avoidance is not possible or incomplete, antihistamines are a common treatment for reactions to indoor allergens. These are medications that fight the effects of the histamine released during an allergic reaction by blocking the action of the histamine on the tissue.

The so-called first-generation antihistamines include diphenhydramine (Benadryl), chlorpheniramine (Chlortrimaton), dimenhydrinate (Dramamine), brompheniramine (Dimetapp and others), clemastine fumarate (Tavist, Allerhist), and dexbrompheniramine (Drixoral). Dryness of the mouth and sleepiness are well-known side effects of first-generation antihistamines. Newer second-generation antihistamines, sometimes referred to as non-sedating antihistamines, include loratadine (Claritin), fexofenadine (Allegra), cetirizine (Zyrtec), fexofenadine (Allegra), and azelastine (Astelin Nasal Spray). These second-generation antihistamines typically have a slower onset of action, are longer acting, and do not have the sedating effects of the first-generation antihistamines.

Decongestants are drugs that reduce swelling in the nasal passages. These drugs can be helpful in reducing allergy symptoms, but they do not treat allergic reactions. Decongestants are available as pills or tablets or can be taken by nasal spray. Decongestant nasal sprays often cause a so-called "rebound effect" or worsening of symptoms if taken for too long, so they should not be used for more than five days without a doctor's recommendation. They should be used with caution in people with heart disease.

Prescription medications, including corticosteroids, cromolyn, and ipratropium (Atropine-like) nasal sprays, are used to manage some allergy symptoms. Montelukast (Singulair) is an inhibitor of a chemical involved in allergic reactions known as leukotriene. Montelukast is used to treat asthma and has also been approved for treatment of hay fever (allergic rhinitis).

Allergy immunotherapy (allergy shots) is a process of stimulation of the immune system with gradually increasing doses of the substances to which a person is allergic. Immunotherapy is very effective for management of allergies to pollen, mites, cats, and especially stinging insects (for example, bees). This treatment usually requires a series of injections and takes up to one year to become effective. The required length of treatment varies, but a typical course of treatment lasts about three years.

Can reactions to indoor allergens be prevented?

Symptoms and signs of allergic reactions to indoor allergens can only be prevented to the extent that the allergens can be avoided or removed from the environment. Sometimes immunotherapy, as described above, can help prevent or decrease the severity of allergic reactions.


Medscape Reference. "Indoor Aeroallergens." eMedicine. 4 Aug. 2010. <>.

Medically Reviewed by a Doctor on 12/19/2014

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Indoor Allergens - Dust Mites at Home Question: How do you control dust mites at home? Do you clean frequently?
Indoor Allergens - Cockroaches Question: What do you do to control cockroaches in your home?
Indoor Allergens - Pollens and Houseplants Question: Which houseplants have been a source of mold or allergens at your house?
Indoor Allergens - Pets Question: How do you deal with allergies caused by household pets? Have you ever had to give away a pet?