context: About 35 million Americans have hay fever. How do you know if you're one of them? First, you need to know what it is -- and isn't. Hay fever is the common term for seasonal allergies. Your doctor will call it seasonal allergic rhinitis. What sets it off? Pollen that certain grasses, weeds, or trees release into the air in spring, summer, and fall. You can also be allergic to things indoors, like dust mites, pet dander, and mold. They cause what doctors call perennial allergic rhinitis because it can hit you any time of year. Treatment for both types of allergies depends on how frequent and severe your attacks are. Symptoms can include: Stuffy or runny nose Sneezing Cough Itchy, watery eyes Itchy mouth, throat, or ears Postnasal drip Dark circles under your eyes Your doctor will know if you have hay fever based on your symptoms and a physical exam. If he needs more proof, he'll use skin and blood tests to see how your body reacts to certain substances. During a skin test the doctor will prick your back or arm with tiny tubes that contain common allergens. If you're allergic to any of them, your skin will get red, itchy, or swollen at the test site. Blood tests show if your body makes blood proteins called antibodies in response to allergy triggers. When an allergen binds to antibodies located in your nose, eyes, and mouth, your body releases chemicals that cause your symptoms. Start with prevention. If you have seasonal allergies, limit outdoor activities when pollen counts are high. Nasal irrigation and saline sprays can help remove allergen particles from your nose. Saline sprays are available over-the-counter, or you can make your own. Use salt and boiled, sterile, or distilled water, but not tap water. Pour or spray into your nose with a neti pot, nasal syringe, or squeeze bottle. If your symptoms don't go away, certain over-the-counter ( OTC) and prescription medications work well. If you have a severe allergy you might try immunotherapy, a long-term process that lowers your response. Several are available to treat hay fever. Nasal corticosteroids: These are considered the safest and most effective treatment. They have few side effects and will greatly ease your symptoms. It may take a few days for them to work, so start to take them a week or two before pollen season begins. In the U. S., several OTC brands are available including budesonide, fluticasone, and triamcinolone. Antihistamines: They can help ease your itches, stop your sneezes, and clear up your runny nose. Doctors recommend the ones that come in pills like cetirizine, fexofenadine, and loratadine. You can get each without a prescription, and they shouldn't make you drowsy. You can also get drops for your runny, itchy eyes. Decongestants: They'll open up your stuffy nose. You can find products like pseudoephedrine or phenylephrine as tablets or pills. You can get decongestant sprays like oxymetazoline and phenylephrine, but these can make your congestion worse if you take them longer than 3 days. If you have hay fever, you're better off with a steroid spray. Decongestant eye drops are also on the market. Like nasal spray, you should only use them for 3 days. Cromolyn ( Crolom): This OTC nasal spray blocks the release of histamines, chemicals that cause your nose to run and make you sneeze. You'll take it three to six times a day, and it may take up to 4 weeks to feel relief from symptoms. Start to take it before allergy season and your symptoms begin. Leukotriene modifiers: The prescription drugs montelukast ( Singulair), often used to treat asthma, stops your body from making the chemicals that cause an allergic reaction. It doesn't work as well as nasal steroids, but it's an option if you can't handle the spray. Ipratropium ( Atrovent), another asthma medication, can help with an ongoing runny nose. Given as shots or daily pills, it offers long-term relief from allergy symptoms. You'll get a tiny dose of the allergens that bother you. Over time your body will get used to them and be less likely to react. You'll get the shots at your doctor's office. You might take them for several years. The pills go under your tongue. You'll probably take the first dose in your doctor's office, but you can take them at home after that. In the U. S. they're only used to treat grass and ragweed allergies. Allergy treatment with medicines or immunotherapy depends on a number of personal things. You and your doctor can decide what's best for you.