Just about everyone knows what hay fever is - the seasonal itching, sneezing, and runny nose caused by the type of pollen that happens to be in the air particularly during the spring or fall. But what most people don’t know is that hay fever is just one manifestation of a more basic condition called allergic rhinitis. Whenever a stuffy nose, dark circles under the eyes, or post-nasal drip persists as a chronic condition, allergic rhinitis could be the cause.
In fact, this condition affects approximately 10% of the U.S. population (roughly 30 million people) and is the most common allergic disorder in the country. No one knows why some people suffer from allergies and others do not. Some evidence suggests that allergies could be a hereditary trait. Other evidence links allergic rhinitis to asthma and eczema. People who suffer from these diseases are more likely to develop allergic rhinitis, too.
What is allergic rhinitis?
Allergic rhinitis is an allergic reaction of the upper respiratory system to a substance called an allergen, which is anything that causes an allergy. These reactions will occur either seasonally or perennially (throughout the year).
Seasonal rhinitis comes and goes with the reproductive cycles of plants and fungi (mold). At certain times of the year specific to their species and geographic region, plants release pollen into the air, and fungi release spores. Those people who are allergic to one or more kinds of these allergens will develop allergic rhinitis.
Tree pollen tends to be the cause of symptoms in the spring. Grass pollen tends to be the culprits in the summer, and ragweed and other weeds tend to be the problem in the fall. Fungi are suspect over a much longer period because they release their spores from late March until November.
Weather influences the severity of allergy symptoms because it affects the daily pollen count. Pollen counts tend to be at their highest on warm, dry, and breezy mornings and at their lowest on rainy, cool days. Generally, the severity of your allergic reaction will correspond to the rise and fall of the pollen count.
As the name suggests, perennial rhinitis occurs all year round. It is caused by allergens whose production is not tied to any seasonal cycle. Common examples are dust mites, animal dander, and molds. Dust mite allergens can be found in pillows, down-filled clothing and bedding, draperies, upholstery, thick carpeting. Symptoms will be steady if you come into contact with the allergen daily, but they can come and go if your contact is only intermittent. It also is possible for a sustained reaction to a perennial allergen to mask a seasonal allergy.
What causes the symptoms?
The symptoms of allergic rhinitis are the result of your immune system protecting itself from what it perceives as an invading substance. Most evidence suggests that genetics determine whether your body will mount this kind of defense.
This allergic response begins with the production of allergic (IgE) antibodies. (special type of proteins produced by the body). The job of these antibodies is to find molecules of the offending substance in the bloodstream and tissues and to escort them to the body’s mast cells for destruction. As the mast cells , type of allergy cells, destroy the allergens, a chemical called histamine is released into the bloodstream and certain mucous membranes (specifically, the lining of the nose or eyes).
Histamine inflames the sinuses and eyelids, making them red and swollen. It also triggers the sneezing reflex. The swelling is designed to block more of the allergens from entering the body, and sneezing is a method of expelling them. Histamine also causes itching and permits fluids to enter the nasal tissue, resulting in congestion and a runny nose.
How are allergies identified?
Because people are often allergic to more than one allergen, identifying which ones are causing your allergy will require a battery of tests. The biggest clue for getting started is the season in which your symptoms occur. Your doctor will use this information to order an initial battery of tests. In most cases, they are skin tests. This procedure involves placing extracts of the allergens on your arm or back and then pricking the skin gently just to break its surface so the extract can enter the outer layer of the skin (epidermis). If you are allergic to the allergen in a particular extract, the pricked area will become red and itchy.
Sometimes, a confirmatory test is needed. This involves injecting a small amount of an extract just under the surface of your skin, much like what happens during a tuberculin (TB) test. Most skin tests take between 15 and 30 minutes, depending on your symptoms and whether confirmatory tests are necessary. Skin tests are the best and fastest way for identifying the substances to which you might be allergic.
Certain conditions, however, could prevent your doctor from performing skin tests. If these conditions exist, your doctor will perform blood tests instead to check the levels of allergic (IgE) antibodies. Elevated levels of certain antibodies can identify particular allergies. Because the blood test is not as sensitive as the skin tests, most doctors use it only when they have no other choice.
How is allergic rhinitis treated?
The most effective treatment for any allergy is simply to avoid the allergen. Air conditioner filters remove 99% of airborne pollen. Facemasks, similar to those worn by surgeons, also can greatly reduce the amount of allergen inhaled while outdoors. For some people, wearing a mask provides enough protection when doing yard work. For others, masks and other precautions are not enough. They need medication to control their symptoms.
Effective drug therapies include antihistamines, topical nasal steroids, and certain decongestants, many of which are available over-the-counter. Antihistamines are effective at treating allergic rhinitis because they block the actions of the histamine produced by the allergic reaction. Most of the older generation that are available over-the-counter, however, can cause drowsiness. For this reason, do not take them when you plan on driving a car, operating heavy equipment, drinking alcohol, or taking other drugs that also cause drowsiness.
The newer antihistamines are less sedating. Loratidine, (Claritin®) and cetirizine (Zyrtec®) are available over-the-counter. Fexofenadine (Allegra®) is the least sedating and is now available over the counter.
The other major effective drug therapy for allergic rhinitis, particularly stuffiness, is nasal steroids. These medications relieve symptoms because they counteract the inflammation caused by the allergic reaction. Prescription nasal steroids include such drugs as fluticasone (Flonase®), mometasone (Nasonex®), budesonide (Rhinocort®), and others.
Decongestants such as phenylephrine (Neo-Synephrine®, et al.) and pseudoephedrine (Sudafed®, et al.) can help to unblock nasal passages and improve breathing. These drugs, however, work only for a few days because they eventually become counterproductive and actually begin to make congestion worse. They can also be associated with adverse side effects including rise in blood pressure. Therefore, these are not recommended for patients who have elevated blood pressure. Do not use decongestants to treat any allergic reaction that persists for more than a few days. Afrin® is an over-the-counter decongestant spray (not a nasal steroid) that can clear your nose temporarily. It is very addictive, and should not be used for more than three days in a row.
What is immunotherapy?
Allergen immunotherapy, commonly known as allergy shots, is a technique designed to increase your tolerance to the substances that cause allergy symptoms. It makes you less sensitive to your allergens, allowing you to tolerate the offending agents. Physicians usually recommend it for people who either do not get good results with medications or do not tolerate them.
During the treatments, an allergen is injected periodically into your body in increasingly larger amounts until an effective dose, called the maintenance dose, is reached. The maintenance dose is given at intervals over three to five years to induce a tolerance to the allergen. In most cases, immunotherapy is very effective at reducing or preventing the development of allergy symptoms whenever you come into contact with the allergen. It usually reduces and often eliminates the need for medications. The effects are long-term for most people who complete an adequate course of allergen immunotherapy.
© Copyright 1995-2016 The Cleveland Clinic Foundation. All rights reserved.
Can't find the health information you’re looking for?
This information is provided by Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 12/31/2012...#8622