As many as 40 percent of children in the US have seasonal allergies (which usually show up by age 6), and the symptoms are pretty much the same as for adults. Depending on where you live (and usually starting around April), a child who’s allergic to pollen or ragweed may have any of these symptoms: a runny nose with clear, watery mucus; repetitive sneezing; nasal congestion; itchy, watery eyes; and an itchy nose and throat. Kids who are allergic to ragweed may get these symptoms around mid-August. Some kids will even develop ear infections as a result of mucus accumulating in their ears.
Perennial or indoor allergies -- like those to pet dander, dust mites, or mold -- usually come with a less runny nose and fewer sneezes, but more nasal congestion and a post-nasal drip that can make your child have trouble sleeping.
At first, it's easy to mistake your child's allergies for a cold, but there are key differences. A cold tends to trigger thick, green mucus, a fever, or body aches, and clears up in about a week, while allergies cause clear, liquidy mucus and won't subside until the trigger goes away.
It's also common for kids with seasonal allergies to be misdiagnosed (usually by teachers) as having pinkeye (conjunctivitis). The biggest difference between pinkeye and allergies is that pinkeye is usually only in one eye, whereas allergy symptoms tend to affect both. You can also examine the goop coming out of your child's eyes. If it's clear and watery, allergies are probably the culprit; if it's thick or yellowish, it could be pinkeye.
If you suspect your child has allergies, talk to your pediatrician (there's no need to go straight to an allergist since most pediatricians can treat mild to moderate allergies very effectively). Most doctors suggest keeping a record of your child's symptoms, since the key to diagnosing allergies is identifying an emerging pattern. Include information like: what the symptoms were, the time of day they were triggered, and what your child was doing when they occurred. If your child is diagnosed with allergies, she will most likely be treated with a two-step approach: avoiding the triggers as much as possible and taking some kind of medication. Doctors often start by suggesting an over-the-counter daily antihistamine like Claritin (for kids 2 and up and possibly even younger) or Zyrtec (for kids 1 and up).