It is possible for a child to be frequently sick with a low immune system, but from a TCM perspective it could be due to phlegm drink, and this is very common. Phlegm drink itself tends to cause a variety of symptoms that are difficult to treat but can be relieved on its own, such as dizziness, headache, nightmares, chest tightness, cough, localized chills in the body, and long outgassing. Cough is one of the most common symptoms.