hay fever seasonal allergy causing inflammation of the mucous membranes of the nose and eyes. It is characterized by itching about the eyes and nose, sneezing, a profuse watery nasal discharge, and tearing of the eyes. The cause is a sensitivity to one or more species of pollens or fungi. In addition, many patients with hay fever develop other allergic conditions, e.g., asthma and sinusitis. In the spring, hay fever may be caused by tree pollens (oak, elm, maple); in summer, by grass pollens, wheat or corn rusts, or fungus spores; in late summer and fall, by ragweed pollen, which is the most common cause. Temporary relief of symptoms may be obtained from antihistamines and decongestants, such as ephedrine. Physicians may resort to corticosteroids in severe cases. Sometimes desensitization measures are taken, consisting of repeated injections of small amounts of the allergen (pollen) until its presence produces no symptoms; however, the treatment must be continued from year to year, since immunity is not permanent. Some relief can be obtained by removing pollen from the air by air conditioners and filters.

HAY FEVER

DEFINITION

Hay fever is an inflammation of the nasal passages. It is an allergic reaction to substances present in the air. The medical name for hay fever is allergic rhinitis (pronounced ri-NI-tuss).

DESCRIPTION

Hay fever is the most common allergic condition (see allergies entry). An allergic condition is a reaction by the body to some substance that is harmless to most people. For example, most people are not bothered by dust in the air. For other people, however, inhaling dust can cause dramatic bodily changes, such as sneezing, coughing, and itchy and watery eyes.

Between 10 and 20 percent of all people in the United States have hay fever. The condition accounts for about 2 percent of all visits to doctors. The drugs used to treat hay fever make up a significant fraction of both prescription and over-the-counter drug sales each year.

There are two types of hay fever: seasonal and perennial. Seasonal hay fever occurs in the spring, summer, and early fall. During these seasons, the level of plant pollens in the air is at its highest. Perennial hay fever occurs all year. It is usually caused by substances found in the air at home or in the workplace. A person may have one or both types of hay fever. Symptoms of seasonal hay fever are worst after being outdoors. Symptoms of perennial hay fever are worst after spending time indoors. Both forms of hay fever can develop at any age. In most cases, they first appear during childhood. They may become either worse or better over time.

CAUSES

Hay fever is a kind of immune reaction. The immune system consists of cells, tissues, and molecules whose job it is to fight off foreign invaders, such as bacteria and viruses. When a foreign substance enters the body, the immune system releases antibodies. Antibodies are chemicals with the ability to destroy the foreign substances.

In the case of hay fever, the immune system becomes confused. It treats dust, pollen, and other harmless substances as if they were dangerous invaders. Substances that cause this kind of reaction are known as allergens. The immune system releases antibodies against allergens the way it does against bacteria, viruses, and other dangerous substances.

The combination of antibody and allergen sets off a series of reactions designed to protect the body. These reactions cause cells and blood vessels to leak fluids. These fluids cause the familiar symptoms of hay fever, such as a runny nose, red and irritated eyes, an itchy nose, and a scratchy throat.

Hay Fever: Words to Know

Allergen:

A substance that provokes an allergic response.

Anaphylaxis:

Increased sensitivity caused by previous exposure to an allergen that can result in blood vessel dilation (swelling) and smooth muscle contraction. Anaphylaxis can result in sharp blood pressure drops and difficulty breathing.

Antibody:

A specific protein produced by the immune system in response to a specific foreign protein or particle called an antigen.

Granules:

Small packets of reactive chemicals stored within cells.

Histamine:

A chemical released by mast cells that activates pain receptors and causes cells to that leak fluids.

Mast Cells:

A type of immune system cell that is found in the lining of the nasal passages and eyelids. It displays a type of antibody called immunoglobulin type E (IgE) on its cell surface and participates in the allergic response by releasing histamine from intracellular granules.

The number of possible allergens found in the air is enormous. Seasonal hay fever is most commonly caused by grass and tree pollen. Pollen is a fine powder by which plants are germinated. A number of weeds can also cause hay fever. These include:

• Ragweed
• Sagebrush
• Lamb's quarters
• Plantain
• Pigweed
• Dock (sorrel)
• Tumbleweed

Perennial hay fever is also caused by a variety of particles found in the air including:

• Body parts of house mites. House mites are tiny insects. They can be seen only with the aid of a microscope. They feed on fibers, fur, and skin shed by people who live in the house. When they die, their body parts get into the air.
• Animal wastes. Animals constantly shed fur, skin flakes, and dried saliva. Common sources of these materials are pet dogs, cats, and birds. These materials easily get into the air. They cause allergic reactions in many people.
• Mold spores. Mold is a fungus that grows in warm, damp places. It lives in basements, bathrooms, air ducts, air conditioners, refrigerator drains, mattresses, and stuffed furniture. Mold reproduces by giving off tiny seed-like particles called spores. These spores are released into the air. They can cause hay fever in many people.

Other possible causes of perennial hay fever include the following:

• Cigarette smoke
• Perfume
• Cosmetics
• Cleansers
• Chemicals used in copy machines
• Industrial chemicals
• Gases given off by construction materials, such as insulation

SYMPTOMS

Common symptoms of hay fever include a tender, itchy, runny nose, accompanied by sneezing and coughing. The sinuses may also begin to swell, causing the eustachian (pronounced you-STAY-shee-un) tube to close up. The eustachian tube connects the inner ear to the throat. The closing of the eustachian tube causes a feeling of stuffiness. Mucus may drip from the sinuses into the throat, causing the throat to become sore. Hay fever may also cause red, itchy, watery eyes. Fatigue and headache are also common.

DIAGNOSIS

Hay fever can usually be diagnosed quite easily. Symptoms and a medical history usually indicate the presence of the condition. When symptoms appear in the spring and disappear in the fall, seasonal hay fever is likely to be the cause. Perennial hay fever can often be diagnosed by asking the patient what substances seem to cause his or her symptoms.

Skin tests are often used in diagnosing hay fever. The first step in conducting a skin test is to place a small amount of a suspected allergen on the skin. The doctor then scratches the skin very lightly. The scratch allows the allergen to get into the bloodstream. After a few minutes, the doctor checks the area being tested. A redness and swelling indicate that the patient is allergic to the material being tested. In most cases, twenty or more materials can be tested at one time. The tests are carried out on the patient's back or forearm.

TREATMENT

The best treatment for hay fever is to avoid the allergens that cause the condition. For example, people who are allergic to grass should not mow the lawn. It may be difficult to avoid allergens, however. In that case, two other treatments are available: drugs and immunotherapy.

Drugs

Some types of drugs used to treat hay fever include the following:

• Antihistamines. Antihistamines block the action of histamine (pronounced HISS-tuh-meen) in the immune system. Histamine is a chemical that causes many of the symptoms of hay fever. Antihistamines can be used after the symptoms of hay fever appear, but they are more effective if used before the symptoms appear. Many older types of antihistamines caused drowsiness. Some newer types do not have this side effect.
• Decongestants. Decongestants constrict (shrink) blood vessels. They reduce the loss of fluid from blood vessels that causes many symptoms of hay fever. Decongestants are sold as pills and as nasal (nose) sprays. One dangerous side effect is that they increase blood pressure and heart rate. They should not be taken for more than a few days at a time.
• Topical corticosteroids. Topical corticosteroids (pronounced kor-tih-ko-STIHR-oids) reduce inflammation and swelling of tissue. They tend to work more slowly and last longer than other forms of medication. As a result, they should be started before the hay fever season begins.
• Mast cell stabilizers. Mast cells are cells produced by the immune system. They are responsible for the early stages of an allergic reaction. Mast cell stabilizers stop the allergic reaction before it gets started. They can also be used before the hay fever season begins. In that case, they reduce the chance that hay fever will develop.

Immunotherapy

Immunotherapy is also known as desensitization or allergy shots. The principle behind immunotherapy is to get the immune system more familiar with an allergen. The procedure consists of a series of injections of the allergen to which the patient is allergic. The first few shots contain a very small amount of the allergen. Over time, the shots contain slightly more allergen

each time. With each shot, the immune system becomes more familiar with the allergen. It produces a more limited reaction to the material. Eventually, the injections contain as much allergen as a patient is likely to encounter in daily life. At that point, the immune system may no longer react to the allergen.

Immunotherapy may take many weeks, months, or even years to achieve this goal. Sometimes the procedure does not work at all. One serious side effect of immunotherapy is anaphylaxis (pronounced a-neh-feh-LAK-siss). Anaphylaxis is characterized by a sharp drop in blood pressure and difficulty with breathing. A person can go into anaphylactic shock and die very quickly. For this reason, the person giving an allergy shot must watch the patient very closely for any unexpected responses.

Alternative Treatment

Some alternative practitioners believe that hay fever should be treated by strengthening the immune system. They may recommend a more balanced diet and changes in one's lifestyle. Vitamin C is sometimes recommended to reduce inflammation of tissues. Some herbs that are recommended for relief of hay fever symptoms include eyebright, bee pollen, and nettle.

PROGNOSIS

Hay fever can usually be kept under control. By avoiding allergens, taking medications, and using immunotherapy, a person can reduce or eliminate most symptoms. In some cases, allergic reactions become worse over time. In other cases, they improve.

PREVENTION

There are many things a person can do to avoid allergic reactions. Some of the most common recommendations for preventing seasonal hay fever include:

• Stay indoors with windows closed during the morning hours, when pollen levels are highest.
• Keep car windows closed while driving.
• Wear a surgical mask when it is necessary to be outdoors.
• Avoid trees, bushes, flowers, and other plants to which one is allergic.
• Wash clothes and hair after being outside.
• Clean air conditioner filters in the home regularly.
• In severe cases, consider moving to an area with fewer allergens.

To reduce the symptoms of perennial hay fever, one needs to avoid mold spores, house dust, and animal wastes by taking steps such as the following:

• Keep the house dry through ventilation and use of dehumidifiers.
• Keep bathroom floors and walls clean with a disinfectant.
• Clean and disinfect air conditioners and coolers.
• Throw out moldy or mildewed books, shoes, pillows, and furniture.
• Vacuum frequently and change the vacuum bag regularly.
• Clean floors and walls with a damp mop.
• Avoid contact with pets to which one is allergic.
• Wash hands after contact with pets and other animals.
• Keep pets out of the bedroom, and off furniture and other areas where their waste materials may collect.
• Have pets bathed and groomed regularly.

FOR MORE INFORMATION

Books

Jelks, Mary. Allergy Plants: That Cause Sneezing and Wheezing. Tampa, FL: World-Wide Publications, 1994.

Novick, N. L. You Can Do Something about Your Allergies. New York: Macmillan, 1994.

Sussman, Les. Relief from Hay Fever and Other Airborne Allergies. New York: Dell Books, 1992.

Organizations

American Academy of Allergy, Asthma, and Immunology. (800) 822–2762. http://www.aaaai.org.

Asthma and Allergy Foundation of America. 1125 15th Street, NW, Suite 502, Washington, DC 20005. 800–7ASTHMA. http://www.aafa.org/home.html.

National Institute of Allery and Infectious Diseases. Building 31, Room 7A-50, 31 Center Drive, MSC 2520, Bethesda, MD 20892-2520. http://www.niaid.nih.gov.

Web sites

"Allergies." About.com [Online] http://allergies.miningco.com (accessed on October 21, 1999).

The On-Line Allergy Center. [Online] http://www.sig.net/~allergy/welcome.html (accessed on October 21, 1999).

hay fever (hay) n. a form of allergy due to pollen, characterized by inflammation of the membrane lining the nose and sometimes of the conjunctiva (vernal or allergic conjunctivitis). The symptoms of sneezing, running or blocked nose, and watering eyes often respond to treatment with antihistamines. Medical name: allergic rhinitis.

hay fe·ver • n. an allergy caused by pollen or dust in which the mucous membranes of the eyes and nose are itchy and inflamed, causing a runny nose and watery eyes.

hay fever Seasonal allergy induced by grass pollens. Symptoms include asthma, itching of the nose and eyes, and sneezing. Symptoms are controlled with an antihistamine.