How Allergies Work
By the time children are 3 years old, 20 percent of them have symptoms of upper respiratory allergies, and that number goes up to 42 percent by age 6. However, even children who are 2 and younger can develop allergic symptoms such as a rash or coughing and wheezing, in reaction to something they've been exposed to (at this age, most likely a food). But the good news is there's a lot you can do to get allergies under control -- and even prevent them in the first place.

The first step is knowing how allergies work. The body's immune system is programmed to produce antibodies to fight viruses, bacteria, and toxins. The swelling and itching you feel at a wound site is the body sending chemicals there so the injury can heal. But sometimes the body reacts to a harmless everyday substance, like a bite of egg or dust particles in the air, as if it were a dangerous invader. It sends chemicals to swell the lining of your nose, for example, if it's something you've inhaled, causing you to sneeze. Or if it's something you've eaten, your gastrointestinal lining gets inflamed, possibly leading to diarrhea.

Babies can't let you know what's bothering them or how they're feeling, so detecting an allergy is often difficult. Here are some common questions I get from parents in my practice.