She's sneezing. Her eyes are scratchy and watering. His nose keeps running. Your child is miserable.

The hallmark of an allergic reaction is itching or sneezing, usually within minutes of exposure,” says allergist Steve Sutton, MD. So if your child has bouts of sneezing and runny nose that seem to come on suddenly, review what he was doing just before the symptoms started.

Was he playing with the cat, or running around outside just after you’d mowed the lawn? Does the condition improve when your child is away from the cat, or the grass?

On the other hand, if it’s a cold, your child will continue to have symptoms, whether she’s with the cat or not. And in addition to sneezing and a runny nose, she might complain of a sore throat, feel achy, and even run a fever. A cold won’t be helped much by medication, Sutton says, whereas your child will probably get relief from an antihistamine if the problem is an allergic one.

If that’s not enough to help you decide, consider your child’s age and the time of year.

“Colds tend to peak in the fall and winter. Allergies are more likely to occur in spring and early fall,” Sutton says. He adds that runny noses and other respiratory symptoms in infants and children under the age of 3 are more likely to be colds.

“Although eczema, asthma and food allergies can be seen early in life, most symptoms related to nasal allergies don’t begin until after age 2 or 3,” Sutton says. “We see allergies peaking in school-age kids.”

If your child is bothered by chronic upper respiratory problems, ask your pediatrician to take a look. The doctor can determine if the problems are caused by a cold, a blockage (such as enlarged adenoids) or an allergic reaction – and can refer you to an allergy specialist or an ENT (ear, nose and throat specialist) for further care, if necessary.