A three-year-old baby with a runny nose and cough is considered to have an infection of the upper respiratory tract that causes this symptom. First of all, you need to observe the color of the child’s nose, if it is clear, it is a viral infection that causes inflammation of the upper respiratory tract, resulting in a runny nose and cough. You can use cold and flu medicine or antiviral medicine to treat it, such as An’erning granules, pediatric aminophenol pseudo-lax dispersible tablets, Pudilan anti-inflammatory oral liquid, and Four Seasons antiviral combination. If the phenomenon of yellow runny nose is caused by bacterial infection, it is necessary to use antibiotics to treat the baby. If the child is not allergic to penicillin, he can take oral amoxicillin clavulanic acid potassium; if there is no allergy to cephalosporins, he can also use pediatric cefixime granules for anti-inflammatory treatment. If the cough is more serious, a chest CT or plain film is needed to rule out bronchitis or pneumonia, and intravenous drip medication is needed for anti-inflammatory treatment, and appropriate antibiotics or antiviral medication should be selected according to the type of infection.