Achoo! Hay fever afflicts 25.5 million people a year

Plagued with itchy, watery eyes, sniffling and sneezing? According to the Centers for Disease Control and Prevention, you're in good company - about 19.9 million U.S. adults and 5.6 million youths may have what is commonly called hay fever.

A seasonal affliction, hay fever, or what doctors call a type of allergic rhinitis, is triggered by pollen from trees, grasses and weeds.

People usually suffer most on hot, dry, windy days.

Allergy symptoms develop when your immune system reacts to the pollen as if it were a risky intruder.

To defend against the pollen, the immune system releases histamine and other chemicals into your body, and this is what leads to the eye, nose and throat problems.

Possible treatment (besides staying indoors, windows closed) when pollen is on the fly includes taking antihistamines or decongestants, using nasal sprays or getting allergy shots, which can help your body build up resistance to the pollen.

Similar symptoms plague people who have what is called perennial allergic rhinitis, a year-round form triggered not by pollen but by sensitivity to pet hair or dander, mold, dust mites or cockroach droppings, among others. All told, an estimated 50 million Americans have some type of allergy, according to the Asthma and Allergy Foundation of America.

Additional common allergens that trigger allergic reactions include bee stings, peanuts, seafood, dairy products, eggs, latex, cosmetics, antibiotics, laundry detergents and some pesticides. While some allergies can be life threatening - such as to insect stings or to some foods - that's rarely the case with hay fever.

While the best approach to spring allergies is avoiding pollen, that may be becoming a bit more difficult. A recent study suggests that, at least in the northern hemisphere, "the ongoing increase in temperature extremes" is contributing to a longer pollen season and more pollen overall.