If your child suffers from allergies or other problems with his immune system, a pediatric allergist/immunologist has special skills to treat your child. Your child’s immune system fights infections. If your child has allergies, her immune system wrongly reacts to things that are usually harmless. Pet dander, pollen, dust, mold spores, insect stings, food, and medications are examples of such things. This reaction may cause her body to respond with health problems such as asthma, hay fever, hives, eczema (a rash), or a very severe and unusual reaction called anaphylaxis. Sometimes, if your child’s immune system is not functioning correctly, he may suffer from frequent, severe, and/or uncommon infections. Examples of such infections are sinusitis (inflammation of one or more of the sinuses), pneumonia (infection of the lung), thrush (a fungus infection in the mouth), and abscesses (collections of pus surrounded by inflamed tissue) that keep coming back. A pediatric allergist/immunologist finds and treats these allergies and immune system problems.