Nine-month-old baby coughing can hang respiratory medicine, if there is other medical history can be considered to hang otolaryngology or cardiology. 1. Respiratory medicine: cough is a kind of reflex defense action of the body for stimulation, the body can clear the respiratory secretion or foreign body through coughing. Infants’ respiratory tracts are not well developed and their immune system is poor, so they are prone to respiratory infections and other problems. These do not need to hang up respiratory medicine. 2. Ear, Nose and Throat (ENT): If the baby has a history of inhalation of foreign bodies, he/she needs to consult the ENT department. 3. Cardiology: If your baby has a history of heart disease, you will need to see a cardiologist. When you go to the doctor’s office, make sure you answer the doctor’s questions truthfully, and pay attention to whether your baby has any other symptoms besides coughing, such as coughing up phlegm, fever, etc. You also need to pay attention to the sound of your baby’s cough, the number of coughs, and the time of coughing, which will help the doctor to make the final diagnosis and treatment. If the cause is unknown, it is recommended to go to the hospital, you can first hang up the respiratory medicine, if necessary, triage.