A baby’s cold is a self-healing illness with a 7-day course. The immune system is not able to recognize the cold virus for the first 3 days of the cold, although it feels out of place. The first 3 days of the common cold show symptoms such as sneezing, runny nose, cough, chills, headache, and even fever and sore and weak bones. After 3 days of the cold, the immune system recognizes the cold virus and starts to organize the battle against it. This process sometimes manifests itself as an increase in symptoms, with high fever, increased cough, and more nasal discharge and phlegm than before. Symptom expression varies depending on the immunity of the baby. In the late stage of the cold, around the 7th day, the immune system starts to clean up the necrotic mucous membrane layer. At this time, the baby feels comfortable and does not feel cold, but there is thicker nasal discharge and phlegm, which is wrapped with necrotic cells, and this is the end of the viral phase.