A baby’s cold is an infection of the upper respiratory tract, which is self-healing and usually lasts 7 days. This course refers to the active period of the cold virus, which is felt for about 7-10 days. The last few days of this period is the cleaning of the destroyed tissue mucosa, and this process does not include secondary infections. Secondary infections are not self-healing, the immune system can resolve some of them, but most of them cause de facto damage to the baby. So if it is a common cold, the baby will be cured in about 1 week without any special treatment. However, if there are some more serious secondary infections, such as secondary bacterial infections, mycoplasma infections, or complications due to influenza, they cannot heal on their own at this time and need active intervention with the doctor to resist the pathogens.