Allergies, which affect 40 to 50 million people, are an inappropriate response of the body's immune system to a foreign substance. The immune system mistakenly thinks the substance is harmful and reacts to try to fight off that substance (called an allergen).

Depending on how the allergen reached your body, your allergic reactions will differ. If you ingest a food allergen, you reactions might (but won't necessarily) be centered around your mouth, stomach and intestines. If the allergen is in the air -- for example, pollen, mold, pet dander or dust -- the reaction is likely to occur in your eyes, nose, lungs and airways. You may get itchy, watery eyes, a runny or stuffy nose and begin to start sneezing or have trouble breathing. Wheezing, a high-pitched whistling sound that occurs when breathing is attempted through narrowed breathing tubes, is also a symptom.

While itchy eyes and sneezing are annoying and will certainly have an impact on your quality of life, especially if you don't get your allergies treated, wheezing is more serious. Wheezing on its own is not necessarily an indication of allergies, though. Other causes of wheezing include asthma, cardiac asthma, bronchitis, viral infections, pneumonia and other diseases and smoking. Taking certain medications, particularly aspirin, may also cause wheezing.

If you are wheezing, whether or not you suspect it is related to allergies, you should see your physician for a proper diagnosis. If you do in fact have allergies, the best way to control them is to avoid the things you are allergic to (an allergist can tell you exactly what allergens to avoid). You may be prescribed medications to help alleviate your symptoms or your doctor might also recommend steroid shots, which are very effective for managing allergies.