Dark rings under the eyes can be as a result of any congestion caused by colds, flu and sinus infections. Allergies are usually accompanied by other symptoms too, such as skin irritations, coughing, watery eyes, constant rubbing of the nose and sneezing.
Allergies are not necessarily something a child is born with – they can develop at any stage. Children and adults can suddenly become allergic to food that they have never had problems with before. Even more mysterious, is the sudden disappearance of allergies. If you notice a child experiencing any symptoms common to allergies, you should get them tested.