A child's immune system fights infections. If a child has allergies, his or her immune system unknowingly reacts to substances (eg. pollen, dust, mold spores, insect bites, food and medications) that are usually harmless. This will result a child's body to respond to several health problems such as rash, asthma, hives, and serious or unusual reaction called anaphylaxis. Sometimes, if a child's immune system is not functioning properly, he or she can suffer from frequent, serious infections. Eg. sinusitis, pneumonia, fungal infection in the mouth and abscesses that come back etc.