Disease: Hay Fever
(Allergic Rhinitis)

    Hay fever facts

    • Hay fever (Allergic rhinitis) is common.
    • Allergy symptoms mimic chronic colds.
    • Allergic rhinitis can lead to other diseases.
    • The best way to treat an allergy condition is to identify the allergic substance and avoid it.
    • Effective treatment is available in many forms.

    What is hay fever? What are the symptoms and signs?

    Hay fever affects up to 30% of all people worldwide, including up to 10% of U.S. children under 17 and 7.8% of U.S. adults. The medical cost of allergic rhinitis is approximately $3.4 billion, mostly due to the cost of prescription medications. These figures are probably an underestimate because many of those affected may attribute their discomfort to a chronic cold. Although childhood hay fever tends to be more common, this condition can occur at any age and usually occurs after years of repeated inhalation of allergic substances. The incidence of allergic disease has dramatically increased in the U.S. and other developed countries over recent decades.

    "Hay fever" is a misnomer. Hay is not a usual cause of this problem, and it does not cause fever. Early descriptions of sneezing, nasal congestion, and eye irritation while harvesting field hay promoted this popular term. Allergic rhinitis is the correct term used to describe this allergic reaction, and many different substances cause the allergic symptoms noted in hay fever. Rhinitis means "irritation of the nose" and is a derivative of rhino, meaning nose. Allergic rhinitis which occurs during a specific season is called "seasonal allergic rhinitis." When it occurs throughout the year, it is called "perennial allergic rhinitis." Rhinosinusitis is the medical term that refers to inflammation of the nasal lining as well as the lining tissues of the sinuses. This term is sometime used because the two conditions frequently occur together.

    Symptoms of allergic rhinitis, or hay fever, frequently include

    • nasal congestion,
    • a clear runny nose,
    • sneezing,
    • nose, eye itching, and
    • excess tear production in the eyes.

    Postnasal dripping of clear mucus frequently causes a cough. Loss of the sense of smell is common, and loss of taste sense occurs occasionally. Nose bleeding may occur if the condition is severe. Eye itching, redness, and excess tears in the eyes frequently accompany the nasal symptoms. The eye symptoms are referred to as "allergic conjunctivitis" (inflammation of the whites of the eyes). These allergic symptoms often interfere with one's quality of life and overall health.

    Allergic rhinitis can lead to other diseases such as sinusitis and asthma. Many people with allergies have difficulty with social and physical activities. For example, concentration is often difficult while experiencing allergic rhinitis.

    Why does an allergic reaction occur?

    An allergic reaction occurs when the immune system attacks a usually harmless substance called an allergen that gains access to the body. To more simply describe this complex immune process, we will make an analogy to a war within the body. The immune system calls upon a protective substance called immunoglobulin E (IgE) antibodies ("E" for "erythema" or redness) to fight these invading allergic substances or allergens. Even though everyone has some IgE, an allergic person has an unusually large army of these IgE defenders -- in fact, too many for his/her own good. This army of IgE antibodies attacks and engages the invading army of allergic substances of allergens.

    As is often the case in war, innocent bystanders are affected in battle. These innocent bystanders are special cells called mast cells. These cells are frequently injured during the warring of the IgE antibodies and the allergic substances. When a mast cell is injured, it releases a variety of chemicals into the tissues and blood, one of which is known as histamine. These chemicals frequently cause allergic reactions. These chemicals are very irritating and cause itching, swelling, and fluid leaking from cells. Through various mechanisms, these allergic chemicals can cause muscle spasm and can lead to lung and throat tightening as is found in asthma and loss of voice.

    What causes allergic rhinitis?

    Any substance can cause an allergy if exposed to a person in the right way. But for all practical purposes and with few exceptions, allergic rhinitis is caused by proteins. Commonly, allergic rhinitis is a result of an allergic person coming in contact several times with protein from plants. Many trees, grasses, and weeds produce extremely small, light, dry protein particles called pollen. This pollen is spread by the wind and is inhaled. These pollen particles are usually the male sex cells of the plant and are smaller than the tip of a pin or less than 40 microns in diameter.

    Even though pollen is usually invisible in the air, pollen is a potent stimulator of allergy. Pollen lodges in the nasal lining tissues (mucus membranes) and other parts of the respiratory tract where it initiates the allergic response. Up to 7.8% of American adults suffer from allergic rhinitis. A person is programmed to be allergic by his/her genetic makeup and is destined to be allergic from birth. Approximately one in four people with allergic rhinitis also has asthma.

    When and where does allergic rhinitis occur?

    Since allergic rhinitis is frequently caused by pollen, symptoms occur when pollen is in the air. Trees primarily pollinate in the spring, while grasses pollinate in the spring and summer. Weeds usually pollinate in the late summer and fall. Of allergy sufferers in the United States, many are allergic to ragweed, about half are allergic to grasses, and fewer are allergic to trees. Of course, many people are allergic to other substances such as mold spores, animal protein, and mites, to name a few. Food is an uncommon cause of allergic rhinitis. If you wish to know the pollen count in your area, this information can often be found in the newspaper in the weather section or you can access the National Allergy Bureau's pollen count information at their web site (http://www.aaaai.org/nab/index.cfm).

    How is allergic rhinitis diagnosed, and how are allergies identified?

    Typically, allergies are initially diagnosed by a combination of characteristic symptoms coupled with exam findings that correspond with allergies.

    If a person is experiencing the typical symptoms of hay fever, a consultation with an allergy specialist can help identify the offending substances. Since the ideal way to manage an allergy is to avoid the substances that cause allergic reaction, it is therefore very important to first identify these substances (allergens). Many allergens can be suspected from information obtained in a patient's particular history. For example, if symptoms usually worsen with exposure to cats, then cat dander protein is a probable allergen causing the symptoms. If cutting grass is associated with the onset of symptoms, then grass allergy is probable. A patient's history of reactions is very important in determining his/her unique allergies. Allergy testing is only done when allergies are debilitating enough that patients desire allergy immunotherapy.

    Because the identification of allergens is important and often difficult to pinpoint, skin testing is often needed to identify exactly the specific substance causing the allergy. Skin testing is now done with minimal discomfort and is performed as follows:

    • A small amount of the suspected allergy substance is placed on the skin.
    • The skin is then gently scratched through the small drop with a special sterile needle. This is known as the prick-puncture method and is typically used for initial evaluations. A second method, known as the intradermal method, involves injection of a small amount of the test substance into the skin. Intradermal testing is more sensitive but also tends to lead to more false-positive results.
    • If the skin reddens and, more importantly, swells, then an individual is said to be "sensitized" to the particular allergen. If typical symptoms occur when a sensitized individual is exposed to the suspected substance, then allergy to that substance is probable.
    • The skin testing described is tolerated by the youngest of patients and should be the standard of testing.
    • Skin testing is not indicated for people who are at risk of a severe (anaphylactic) allergic reaction, who have certain skin conditions, or who are taking certain medications.

    A number of blood tests are also available to aid in the diagnosis of allergy. These blood tests may be useful in people who cannot be skin tested due to skin diseases, who are taking medications that interfere with skin testing, or who are at a high risk of having an anaphylactic reaction to skin testing. These blood tests typically use various techniques to look for IgE antibodies in the blood and by inference suggest allergy in the tissues. If the allergy testing agrees with the history of symptoms upon exposure to the substance, then a diagnosis of allergic rhinitis is likely.

    Why does an allergic reaction occur?

    An allergic reaction occurs when the immune system attacks a usually harmless substance called an allergen that gains access to the body. To more simply describe this complex immune process, we will make an analogy to a war within the body. The immune system calls upon a protective substance called immunoglobulin E (IgE) antibodies ("E" for "erythema" or redness) to fight these invading allergic substances or allergens. Even though everyone has some IgE, an allergic person has an unusually large army of these IgE defenders -- in fact, too many for his/her own good. This army of IgE antibodies attacks and engages the invading army of allergic substances of allergens.

    As is often the case in war, innocent bystanders are affected in battle. These innocent bystanders are special cells called mast cells. These cells are frequently injured during the warring of the IgE antibodies and the allergic substances. When a mast cell is injured, it releases a variety of chemicals into the tissues and blood, one of which is known as histamine. These chemicals frequently cause allergic reactions. These chemicals are very irritating and cause itching, swelling, and fluid leaking from cells. Through various mechanisms, these allergic chemicals can cause muscle spasm and can lead to lung and throat tightening as is found in asthma and loss of voice.

    What causes allergic rhinitis?

    Any substance can cause an allergy if exposed to a person in the right way. But for all practical purposes and with few exceptions, allergic rhinitis is caused by proteins. Commonly, allergic rhinitis is a result of an allergic person coming in contact several times with protein from plants. Many trees, grasses, and weeds produce extremely small, light, dry protein particles called pollen. This pollen is spread by the wind and is inhaled. These pollen particles are usually the male sex cells of the plant and are smaller than the tip of a pin or less than 40 microns in diameter.

    Even though pollen is usually invisible in the air, pollen is a potent stimulator of allergy. Pollen lodges in the nasal lining tissues (mucus membranes) and other parts of the respiratory tract where it initiates the allergic response. Up to 7.8% of American adults suffer from allergic rhinitis. A person is programmed to be allergic by his/her genetic makeup and is destined to be allergic from birth. Approximately one in four people with allergic rhinitis also has asthma.

    When and where does allergic rhinitis occur?

    Since allergic rhinitis is frequently caused by pollen, symptoms occur when pollen is in the air. Trees primarily pollinate in the spring, while grasses pollinate in the spring and summer. Weeds usually pollinate in the late summer and fall. Of allergy sufferers in the United States, many are allergic to ragweed, about half are allergic to grasses, and fewer are allergic to trees. Of course, many people are allergic to other substances such as mold spores, animal protein, and mites, to name a few. Food is an uncommon cause of allergic rhinitis. If you wish to know the pollen count in your area, this information can often be found in the newspaper in the weather section or you can access the National Allergy Bureau's pollen count information at their web site (http://www.aaaai.org/nab/index.cfm).

    How is allergic rhinitis diagnosed, and how are allergies identified?

    Typically, allergies are initially diagnosed by a combination of characteristic symptoms coupled with exam findings that correspond with allergies.

    If a person is experiencing the typical symptoms of hay fever, a consultation with an allergy specialist can help identify the offending substances. Since the ideal way to manage an allergy is to avoid the substances that cause allergic reaction, it is therefore very important to first identify these substances (allergens). Many allergens can be suspected from information obtained in a patient's particular history. For example, if symptoms usually worsen with exposure to cats, then cat dander protein is a probable allergen causing the symptoms. If cutting grass is associated with the onset of symptoms, then grass allergy is probable. A patient's history of reactions is very important in determining his/her unique allergies. Allergy testing is only done when allergies are debilitating enough that patients desire allergy immunotherapy.

    Because the identification of allergens is important and often difficult to pinpoint, skin testing is often needed to identify exactly the specific substance causing the allergy. Skin testing is now done with minimal discomfort and is performed as follows:

    • A small amount of the suspected allergy substance is placed on the skin.
    • The skin is then gently scratched through the small drop with a special sterile needle. This is known as the prick-puncture method and is typically used for initial evaluations. A second method, known as the intradermal method, involves injection of a small amount of the test substance into the skin. Intradermal testing is more sensitive but also tends to lead to more false-positive results.
    • If the skin reddens and, more importantly, swells, then an individual is said to be "sensitized" to the particular allergen. If typical symptoms occur when a sensitized individual is exposed to the suspected substance, then allergy to that substance is probable.
    • The skin testing described is tolerated by the youngest of patients and should be the standard of testing.
    • Skin testing is not indicated for people who are at risk of a severe (anaphylactic) allergic reaction, who have certain skin conditions, or who are taking certain medications.

    A number of blood tests are also available to aid in the diagnosis of allergy. These blood tests may be useful in people who cannot be skin tested due to skin diseases, who are taking medications that interfere with skin testing, or who are at a high risk of having an anaphylactic reaction to skin testing. These blood tests typically use various techniques to look for IgE antibodies in the blood and by inference suggest allergy in the tissues. If the allergy testing agrees with the history of symptoms upon exposure to the substance, then a diagnosis of allergic rhinitis is likely.

    Source: http://www.rxlist.com

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