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. What most people don't know is that hay fever is just one sign 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 (long-term) 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 (inherited) 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 (during certain seasons of the year) 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 (depending on their species and where they are located), plants release pollen into the air, and fungi release spores. 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 in the summer, and ragweed and other weeds in the fall. Fungi are suspect over a much longer period because they release their spores from late March until November.
Weather influences how severe allergy symptoms will be 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, your allergic reaction will be severe or mild, depending on 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, and thick carpeting. Symptoms will be steady if you come into contact with the allergen every day, but they can come and go if you only have occasional contact. It also is possible that if you have a constant reaction to a perennial allergen that you may actually have a seasonal allergy.
What causes the symptoms of allergic rhinitis?
The symptoms of allergic rhinitis are caused by your immune system protecting itself from what it identifies as an invading substance. Most evidence suggests that genetics (heredity) 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 (a type of allergy cell) for destruction. As the mast 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 makes the sinuses and eyelids 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 getting rid of them. Histamine also causes itching and allows fluids to enter the nasal tissue, which results in congestion (stuffiness) and a runny nose.
How are allergies identified?
Because people are often allergic to more than one allergen, you will need to have several tests done to identify which ones are causing your allergy. The biggest clue for getting started is the season in which your symptoms occur. Your doctor will use this information to order the first tests.
In most cases, they are skin tests. In this procedure, the doctor places extracts of the allergens on your arm or back and then pricks 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 that extract, the pricked area will become red and itchy.
Sometimes another test is needed to confirm the first test. 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 second tests are needed. 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. Higher 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 antihistamines 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 (not as likely to cause drowsiness). Loratidine (Claritin®) and cetirizine (Zyrtec®) are available over the counter. Fexofenadine (Allegra®) is also less sedating and is now available over the counter.
The other major effective drug therapy for allergic rhinitis, especially stuffiness, is nasal steroids. These medications relieve symptoms because they reduce the inflammation (swelling) caused by the allergic reaction. Prescription nasal steroids include such drugs as fluticasone (Flonase®), mometasone (Nasonex®), budesonide (Rhinocort®), and others. Various nasal steroids have become available over the counter, also.
Decongestants such as phenylephrine (Neo-Synephrine®, et al.) and pseudoephedrine (Sudafed®, et al.) can help to unblock nasal passages and improve breathing. They can also be associated with harmful side effects, including a rise in blood pressure. Therefore, these are not recommended for patients who have higher blood pressure. 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?
Subcutaneous immunotherapy, also 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. Doctors 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 into your body in increasingly larger amounts over a period of time until an effective dose, called the maintenance dose, is reached. The maintenance dose is given at intervals over three to five years to create a tolerance to the allergen.
Sublingual immunotherapy has recently become available in the United States. It is a pill that is placed under the tongue, usually three months before the season that causes the allergies. It is maintained daily until the season comes to the end. At this time, the only oral immunotherapy available is to grass (summer allergies) and ragweed (fall allergies).
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.
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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: 3/12/2016...#8622