Allergies happen when a person's body releases a chemical called histamine, and that can cause sneezing, itchy eyes and congestion. There can be more extreme reactions, but usually it is more a matter of discomfort. Pollen from plants is the most common cause of allergies, though there can be any number of things that can cause symptoms. Food allergies are also fairly common, especially with children. The treatment of allergies is normally done anti-histamines, and the treatment for children is the same as for adults, but at a lower level of medication. There are over the counter anti-histamines for children, and in strong cases, there are prescription level anti-histamines. When there are dangerous levels of allergies, there is epinephrine, which is only available by prescription.