Live ScienceHealth Reference: Hay Fever & Seasonal Allergies: Symptoms, Causes & Treatment By Heather Whipps, Live Science Contributor | February 18, 2015 10:32pm ET MORE Credit: Sinus Relief Now" (Perigee Trade, 2006), told Live Science. "Rather, it is an allergy to weeds that pollinate." Doctors and researchers prefer the term "allergic rhinitis." About 8 percent of adults in the United States have allergic rhinitis, Josephson said. Among children in the United States, 9 percent reported having allergic rhinitis symptoms during the past 12 months, according to a 2012 study, he added. Worldwide, between 10 and 30 percent of people are affected by allergic rhinitis, he said. Symptoms The symptoms of allergic rhinitis may at first feel like those of a cold. But in the case of hay fever, symptoms usually appear when a person encounters an allergen, such as pollen or mold. Symptoms include itchy eyes, itchy nose, itchy throat, itchy ears, sneezing, irritability, nasal congestion and hoarseness. People may also experience cough, postnasal drip, sinus pressure or headaches, decreased sense of smell, snoring, sleep apnea, fatigue and asthma, Josephson said. Many of these symptoms are an immune overreaction by the body attempting to protect the vital and sensitive respiratory system from outside invaders. The antibodies produced by the body succeed in keeping the foreign invaders out, but also cause the symptoms characteristic of allergic responses. People can develop hay fever at any age, but most people are diagnosed with the disorder in childhood or early adulthood, according to the Mayo Clinic. Symptoms typically become less severe as people age. Often, children may first experience food allergies and eczema before developing hay fever, Josephson said. "This then worsens over the years, and patients then develop allergies to indoor allergens like dust and animals, or seasonal rhinitis, like ragweed (hay fever), grass pollen, molds and tree pollen." Hay fever can also lead to other medical conditions. People who are allergic to weeds are more likely to get other allergies and develop asthma as they age, Josephson said. But those who receive immunotherapy, such as allergy shots that help people's bodies get used to allergens, are less likely to develop asthma, he said. Common allergens The most common allergen is pollen, a powder released by trees, grasses and weeds that fertilize the seeds of neighboring plants. As plants rely on the wind to do the work for them, the pollination season sees billions of microscopic particles fill the air, and some of them end up in people's noses and mouths. Spring bloomers include ash, birch, cedar, elm and maple trees, plus many species of grass. Weeds pollinate in the late summer and fall, with ragweed being the most volatile. The pollen that sits on brightly colored flowers, it is interesting to note, is rarely responsible for hay fever, because it is heavier and falls to the ground rather than being borne in the air. Also, bees and other insects carry that pollen directly from one flower to the next without ever bothering human noses. Mold allergies are different. Mold is a spore that grows on rotting logs, dead leaves and grasses. While dry-weather mold species exist, many types of mold thrive in moist, rainy conditions, releasing their “seeds” overnight. Both in the spring or fall allergy seasons, pollen is released mainly in the morning hours and travels best on dry, warm and breezy days. Pollen count How do scientists know how much pollen is in the air? It’s more than just a guess. Specialists charged with counting pollen set a trap where ambient air flows freely. The trap — usually a glass plate or rod coated with adhesive — is analyzed every few hours, and the number of particles collected is then averaged to reflect the particles that would pass through the area in any 24-hour period. That measurement is converted to pollen per cubic meter. Mold counts work much the same way. A pollen count is an imprecise measurement, scientists admit, and an arduous one — at the analysis stage, pollen grains are literally counted one by one under a microscope. It is also highly time-consuming to discern between types of pollen, so they are usually bundled into one variable. Given the imprecise nature of the measurement, total daily pollen counts are often listed simply as low, moderate or high. People who have access to pollen counts may decide to stay indoors if a pollen count is high, or simply may take medication to help control their symptoms. Tests & diagnosis A physician will take patient history and do a thorough physical examination if a person reports having hay fever-like symptoms. If necessary, the physician will do an allergy test. According to the Mayo Clinic, people can get a skin prick test, in which doctors prick the skin on a person's arm or upper back with different substances to see if any cause an allergic reaction, such as a raised bump called a hive. A person can also do an allergy blood test. This test rates the immune system's response to a particular allergen by measuring the amount of allergy-causing antibodies in the bloodstream, according to the Mayo Clinic. Hay fever treatments Short of staying indoors through hay fever season, allergy sufferers may choose to combat symptoms with medication designed to shut down or trick the immune sensitivity in the body. Whether over-the-counter or prescription, most allergy pills work by sending chemicals that bind naturally to histamine — the protein that reacts to the allergen and causes an immune response — coursing through the body, negating the protein’s effect. Other allergy remedies attack the symptoms at the source. Nasal sprays contain active ingredients that decongest by soothing irritated blood vessels in the nose, while eye drops both moisturize and reduce inflammation. Doctors may also prescribe allergy shots for those particularly afflicted, Josephson said. Doctors may also recommend allergy shots, a neti pot that can rinse the sinuses, or a Grossan Hydropulse, an irrigating system that cleans the nose of pollens, infection and environmental irritants, Josephson said. Alternative and holistic options, along with acupuncture, may also help people with hay fever, Josephson said. People can also avoid pollen by keeping their windows closed in the spring, and by using air purifiers and air conditioners at home. Additional reporting by Live Science Staff Writer Laura Geggel. Follow her on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Additional resources Learn about rhinitis treatment and management at the American Academy of Allergy Asthma & Immunology. Read how thunderstorms can exacerbate symptoms in people with hay fever at The Washington Post. Acupuncture may reduce hay fever symptoms, but only temporarily, The New York Times reports. Editor's Recommendations 9 Myths About Seasonal Allergies Allergy Medications: Which Drugs Treat Which Symptoms Got Allergies? Avoid These 7 Mistakes More from Live Science What Is Ovulation? In Hot Water: Thousands of Public Pools Fail Health Inspections Kids with Puzzling Stomachaches Might Benefit from Probiotics Will Your Weight Loss Program Work? 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