Baby runny nose into yellow snot may be related to infection factors, such as bacterial or viral secondary bacterial infection, but also may be related to allergic rhinitis and other factors. 1. Infectious factors: the baby running clear nose is generally inflammation of the nasal mucosa, from the clear nasal discharge into yellow nasal discharge is considered to be viral secondary bacterial infection, you can take the child to the hospital to check the blood routine to clarify the diagnosis. 2. Allergic rhinitis: allergic rhinitis can lead to the symptoms of the baby runny nose, such as the baby allergic to dust, pollen, animal fur, such as the combination of bacterial infections, there can be a clear runny nose into yellow runny nose symptoms. Baby runny nose into runny yellow nose may also have other reasons, it is recommended to go to the hospital in a timely manner to carry out relevant examinations, clear cause of the disease and then actively targeted treatment, so as not to miss the opportunity for treatment.