Phlegm can build up at the back of your throat when you lie down in bed and trigger coughing at night. “The most common cause of this is an upper respiratory tract infection such as colds or flu ...
Dr Munisamy said if your cough is caused by a cold or flu it could be accompanied by yellow phlegm, as well as: Headaches Muscle aches Sneezing Increased temperature/fever. He advised ...