A child coughing up phlegm who wants to rule out the presence of a foreign body in the thoracic organs can simply undergo a tracheal endoscopy. The production of phlegm can be triggered by the presence of a foreign body in the trachea that obstructs or irritates the mucous membranes. Tracheal endoscopy is an accurate way to directly visualize the presence of a foreign body in the trachea. If a localized foreign body does exist in the child’s thoracic trachea, it can be removed directly through endoscopic removal to remove the tracheal obstruction. However, local anesthesia medication is needed to reduce the irritation response of the mucous membranes prior to the examination. When there is a foreign body obstruction in the trachea, the foreign body itself can cause different degrees of irritation or damaging effects on the mucosa, which triggers an increase in secretions on the surface of the pharyngeal mucosa and the formation of sputum. After endoscopic observation and removal, expectorant medication can also be taken appropriately for effective relief, such as acetylcysteine or bromhexine hydrochloride. After coughing up sputum or tracheal foreign bodies, children need to go to the hospital as soon as possible for foreign body removal or medication to avoid causing breathing difficulties or tracheal damage. When using medication, it is necessary to follow the doctor’s instructions.