Allergy is the most common illness in the world. It is characterized by the immune system's reaction to substances that are viewed by the body as potentially harmful. The body launches an attack on these substances which is manifested by the symptoms experienced in an allergy attack. There are many substances that can cause an allergic reaction. Among them are peanuts, shellfish, eggs, milk, dust, insect bites and pollen.

Also known as allergic rhinitis, hay fever is usually characterized by an allergic reaction to pollen. The illness is named after the "haying season" when pollen grains in the air are in abundance. Since pollen carried by the wind is the more popular culprit, you should be aware of the most common plants releasing these pollen grains in the air. Trees including birch, alder, hazel, hornbeam, horse chestnut, willow, poplar, plane, lime and olive cause hay fever. Among these, birch and olive pollen are the most dominant. On the other hand, grass pollen from rye and timothy are responsible for about 90% of the total hay fever cases.

Effects of hay fever vary form person to person. Some experience mild reactions while others suffer severe reactions. Symptoms of the illness include coughing, headache, itching nose, runny nose and sneezing. You might also experience impaired smelling functions and sensitivity to flavors. Your eyes will water from the irritation in your nose. Sore throat, wheezing and conjunctivitis are also common reactions.

Hay fever is usually diagnosed by determining the patient's history of symptoms. Your doctor will ask you the frequency of your symptoms, severity and onset. Changes in your diet, exposure to pets and allergens as well as weather conditions will all be considered in the evaluation for hay fever. Skin testing is also performed to determine specific sensitivity to particular allergens. Since cross-reactivity is normal, your doctor will naturally check you for reactions to cross-reacting substances.

To prevent hay fever, you should avoid being exposed to pollen. If you must go outdoors, try to wear a protective face mask for filtering pollen. You should also avoid going out during the early mornings and evenings when pollen levels are high. When drying your clothes, never put them outside where they can be exposed to pollen. The pollen will attach to the clothes you placed outside for longer than a moment and if you wear these clothes it's possible that you could have an allergic reaction. Another activity you should avoid is mowing your lawn. This activity will disperse pollen in the air, increasing your chances for a hay fever attack. Some doctors recommend putting little cream on the nostrils and around the eyes to prevent pollen from entering these areas.

There are currently several available medications for treating symptoms of hay fever. These include fast-acting antihistamines, short-acting antihistamines, longer-acting antihistamines, leukotriene receptor antagonists, corticosteroid nasal sprays, topical decongestants, cromolyn sodium, allergy shots and herbal remedies. Any of these medications can relieve symptoms of hay fever effectively. You should make sure that when taking these medications, you will not be driving or operating heavy machineries since drowsiness can be experienced when taking medication like antihistamines.