Yellow phlegm in the morning is not cancer, but a symptom of bronchitis or chronic pharyngitis, so patients do not need to worry too much. The yellow phlegm indicates that the body is on fire and the lung fire is strong. Since the phlegm in the body cannot be discharged out of the body in time when sleeping at night, it accumulates more and more in the body, resulting in a large amount of yellow phlegm when waking up in the next morning. You can use drugs such as Ambroxol Hydrochloride to stop coughing and dissolve phlegm, or you can take drugs such as Mucosolvan under the advice of your doctor for treatment. Usually, you should eat more snow pear, grapefruit and other foods to remove heat and moisten the lungs, eat more fresh vegetables and fruits, keep your diet light, and go to the regular hospital at any time if you feel uncomfortable.