Coughs, colds and flu are all respiratory illnesses that can cause symptoms such as coughing, sneezing, runny nose, and fever. Colds and flu are caused by viruses, and a cough is usually a symptom of this. Coughs can also be the symptoms of allergies or smoking.
Colds and the Flu are highly contagious and can be spread through respiratory secretions such as saliva or mucous that are expelled when a person coughs or sneezes. It is important to wash your hands frequently, and cover your mouth and nose when you cough or sneeze to prevent these viruses spreading.