Table of Contents
What is Allergic Rhinitis and Definition
Allergic Rhinitis is a HYPERSENSITIVITY REACTION to inhaled allergens – also called seasonal rhinitis or hay FEVER, affects the mucous membranes inside the NOSE (nasal mucosa). Allergic rhinitis affects about 40 million adults in the United States, making it one of the most common hypersensitivity reactions. The condition tends to develop in childhood and continue through adulthood, though some people who have allergic rhinitis as children seem to outgrow their sensitivities as they become adults.
MUCOSA-ASSOCIATED LYMPHOID TISSUE (MALT) infiltrates the nasal mucosa. Within the MALT are numerous mast cells, the surfaces of which harbor IMMUNOGLOBULIN E (IgE) antibodies. These antibodies react within hours to the presence of airborne allergens such as pollens. Allergic rhinitis is most common in the spring and the fall, though some people also experience symptoms in the summer, depending on what allergies they have.
Allergic rhinitis is primarily a type I (IgE) hypersensitivity reaction, in which symptoms developing fairly immediately after contact with the ALLERGEN. The most common allergens associated with allergic rhinitis are tree pollens, grass pollens, and weed pollens. Other potential allergens include dust mites, pet dander, and other substances that are continuously present in the environment.
Symptoms of and Diagnostic Path
The symptoms of rhinitis range from mild to debilitating. The classic symptoms occur in response to the presence of allergens and include
- nasal congestion
- RHINORRHEA (runny nose) Some people also develop
- swollen, itchy, reddened eyes (ALLERGIC CONJUNCTIVITIS)
- dark circles under the eyes (“allergic shiners”)
- OTITIS media (middle ear INFECTION)
- PHARYNGITIS (sore THROAT) from postnasal drip (mucus draining down the back of the throat)
- physical irritation of the nose due to frequent sneezing, blowing, and rubbing
The doctor makes the diagnosis based on the presentation of symptoms and the person’s description of how the symptoms develop and how long they last.
Allergic Rhinitis: Treatment Options and Outlook
Treatment combines avoiding the allergen when possible with medications to control symptoms. Such medications typically include antihistamine nasal sprays, corticosteroid nasal sprays, oral ANTIHISTAMINE MEDICATIONS, and oral decongestant medications. Another classification of DRUG that is sometimes effective for allergic rhinitis is the leukotriene receptor antagonist, which blocks the action of LEUKOTRIENES (other chemicals that mediate the IMMUNE RESPONSE).
The leukotriene receptor antagonist medication approved for use in the United States is montelukast (Singulair). Cromolyn sodium nasal spray targets mast cells, reducing their ability to release immune mediator chemicals such as histamine, PROSTAGLANDINS, and leukotrienes. DESENSITIZATION, commonly called allergy shots, is an option for some people. Desensitization works by exposing the IMMUNE SYSTEM to small amounts of the allergen over time to retrain the immune response to ignore the allergen.
Older antihistamine medications such as diphenhydramine (Benadryl) are very effective though cause drowsiness. Newer antihistamine medications such as loratadine (Claritin) are equally effective for most people and cause significantly less drowsiness. Antihistamines block the action of histamines, chemicals that mediate (initiate and facilitate) the processes of the immune response that result in the symptoms. Most antihistamines are available as OVER-THE-COUNTER (OTC) DRUGS that do not require a doctor’s prescription. GINGER, available in various preparations, contains a mild antihistamine.
Oral decongestant medications available over the counter in the United States are pseudoephedrine and phenylephrine, though there are several OTC decongestant nasal sprays. Many OTC allergy products combine a decongestant with an antihistamine. Decongestants work by constricting the blood vessels in the nasal mucosa, reducing the availability of fluid to the tissues. Chronic or long-term use of decongestants can result in rebound congestion, a condition in which the nasal membranes swell in the absence of the decongestant. Nose drops and nasal sprays containing saline (salt solution) are often as effective in relieving congestion. They work by soothing the nasal mucosa and flushing away topical irritants, including allergens.
Risk Factors and Preventive Measures
Allergic rhinitis is very common, affecting 20 percent of the American adult population. The most effective measure to reduce symptoms is to limit or eliminate exposure to the allergens that trigger the hypersensitivity response. Many people are able to mitigate symptoms by using allergy medications regularly for the duration of the allergy season.
There appears to be a GENETIC PREDISPOSITION for chronic allergic rhinitis, also called atopic rhinitis, which has more extensive symptoms that tend to be more perennial (ongoing) than seasonal. People who have atopic rhinitis have increased risk for other atopic conditions such as ALLERGIC ASTHMA (also called atopic asthma), atopic CONJUNCTIVITIS, and atopic DERMATITIS. A flare of symptoms in one atopic condition often brings on symptoms in another.