(See also Overview of Allergic Reactions.)
Perennial allergies may occur at any time of year—unrelated to the season—or may last year-round. Perennial allergies are often a reaction to house dust. House dust may contain mold and fungal spores, fibers of fabric, animal dander, dust mite droppings, and bits of insects. Substances in and on cockroaches are often the cause of allergic symptoms. These substances are present in houses year-round but may cause more severe symptoms during the cold months when more time is spent indoors. (Substances that trigger an allergic reaction are called allergens.)
Usually, perennial allergies cause nasal symptoms (allergic rhinitis) but not eye symptoms (allergic conjunctivitis). However, allergic conjunctivitis can result when allergens are inadvertently rubbed into the eyes. The cleaning solutions for contact lenses can also sometimes cause an allergic reaction.
Perennial rhinitis is often caused by something other than an allergy, such as aspirin or another nonsteroidal anti-inflammatory drug (NSAID) or another form of rhinitis.
The most obvious symptom of perennial allergies is a chronically stuffy nose. The nose runs, producing a clear watery discharge. The nose, roof of the mouth, and back of the throat may itch. Itching may start gradually or abruptly. Sneezing is common.
The eustachian tube, which connects the middle ear and the back of the nose, may become swollen. As a result, hearing can be impaired, especially in children. Children may also develop chronic ear infections. Some people have recurring sinus infections (chronic sinusitis) and growths inside the nose (nasal polyps).
When affected, the eyes water and itch. The whites of the eyes may become red, and the eyelids may become red and swollen. The skin under the eyes can become dark (allergic shiner).
Tests are needed only if people do not respond to treatment.
In such cases, skin prick tests can help confirm the diagnosis and identify the trigger for symptoms (such as dust mites or cockroaches). For these tests, a drop of each extract is placed on the person’s skin, which is then pricked with a needle. Doctors then watch to see if there is a wheal and flare reaction (a pale, slightly elevated swelling surrounded by a red area).
An allergen-specific immunoglobulin (IgE) test is done if results of the skin test are unclear. For this test, a sample of blood is withdrawn and tested.
Avoiding or removing the allergen, if possible, is recommended, thus preventing the development of symptoms.
If people are allergic to house dust, animal dander, or other indoor allergens, some changes in the environment may prevent or lessen symptoms:
Removing items that collect dust, such as knickknacks, magazines, and books
Removing soft toys
Replacing upholstered furniture and carpets or vacuuming them frequently
Replacing draperies and shades with blinds
Frequently washing bed sheets, pillowcases, and blankets in hot water
Treating homes with heat-steam
Covering mattresses and pillows with finely woven fabrics that cannot be penetrated by dust mites and allergen particles
Using synthetic-fiber pillows
Frequently cleaning the house, including dusting, vacuuming, and wet-mopping
Using air conditioners and dehumidifiers to reduce the high indoor humidity that encourages the breeding of dust mites
Using high-efficiency particulate air (HEPA) vacuums and filters
Limiting pets to certain rooms or keeping them out of the house and washing the pet frequently
Avoiding the allergen is the best way to treat as well as prevent allergies.
Drug treatment of perennial allergies is similar to that for seasonal allergies. It includes corticosteroid nasal sprays, antihistamines, and decongestants.
A corticosteroid nasal spray is usually very effective and is used first. Most of these sprays have few side effects, although they can cause nosebleeds and a sore nose.
An antihistamine, taken by mouth or used as a nasal spray, can be used instead of or in addition to a corticosteroid nasal spray. Antihistamines are often used with a decongestant, such as pseudoephedrine, taken by mouth.
Many antihistamine-decongestant combinations are available over the counter as a single tablet. However, people with high blood pressure should not take a decongestant unless a doctor recommends it and monitors its use. Also, people who take a monoamine oxidase inhibitor (a type of antidepressant) cannot take a product that combines an antihistamine and a decongestant.
Antihistamines may have side effects, particularly anticholinergic effects. Anticholinergic effects include sleepiness, dry mouth, blurred vision, constipation, difficulty with urination, confusion, and light-headedness.
Decongestants are also available over the counter as nose drops or sprays. They should not be used for more than a few days at a time because using them continually for a week or more may worsen or prolong nasal congestion—called a rebound effect—and may eventually result in chronic congestion.
Side effects tend to be fewer and less severe with nasal sprays than with drugs taken by mouth.
Other drugs are sometimes useful. Cromolyn is available by prescription as a nasal spray and may help relieve a runny nose. To be effective, it must be used regularly. Azelastine (an antihistamine) and ipratropium (a drug that inhibits acetylcholine), both available by prescription as nasal sprays, may be effective. But these drugs can have anticholinergic effects similar to those of antihistamines taken by mouth, especially drowsiness.
Montelukast, a leukotriene modifier available by prescription, reduces inflammation and helps relieve a runny nose. It is best used only when other drugs are ineffective. Possible side effects include confusion, anxiety, depression, and abnormal muscle movements.
Regularly flushing out the sinuses with a warm water and salt (saline) solution may help loosen and wash out mucus and hydrate the nasal lining. This technique is called sinus irrigation.
When these treatments are ineffective, a corticosteroid may be taken by mouth or by injection for a short time (usually for fewer than 10 days). If taken by mouth or injection for a long time, corticosteroids can have serious side effects.
If other treatments are ineffective, allergen immunotherapy helps some people.
Immunotherapy is needed in the following situations: