If you have watery eyes or a stuffy, runny nose, you could have a cold. But if you get these symptoms only when you're outside, near pets, or eat certain foods, you could have an allergy.

Allergies occur when your immune system overreacts to a specific substance called an allergen, or trigger. Your immune system may identify the trigger—which is actually harmless—as a threat ...

Certain plants and pollutants are common allergic asthma triggers. Learn which outdoor allergens trigger asthma symptoms and ...