A cough is an involuntary reflex triggered by irritation of the airways or the nerves responsible for the reflex. Many conditions can trigger the cough reflex, giving rise to different types of coughing with distinguishing characteristics. Noting the characteristics of a cough helps narrow the list of possible causes. Medical professionals use a variety of descriptors to categorize different types of cough. In some cases, more than one descriptor may apply.
A dry cough, also known as a non-productive cough, produces little to no phlegm. Upper respiratory tract infections remain a common cause of dry cough, reports Penn State College of Medicine's Milton S. Hershey Medical Center. Types of upper respiratory tract infections include influenza, head colds, laryngitis, sore throats, croup, tonsillitis and acute sinusitis. Viruses cause most upper respiratory tract infections, which typically resolve without medications in one to two weeks. Dry coughing sometimes persists for several weeks after the resolution of other symptoms of an upper respiratory tract infection.
Possible causes of a persistent dry cough include cough-variant asthma; allergies; chronic sinusitis; gastroesophageal reflux, or stomach acid in the esophagus; certain medications; chronic exposure to airway irritants, such as air pollution or cigarette smoke; and accidental inhalation of a foreign body, such as part of a toy or game.
A wet cough, also known as a productive cough, produces phlegm. A wet cough indicates a disease process involving excessive production of lung mucus or fluid leakage into the airways. Pneumonia is a frequent cause of the sudden onset of a productive cough. With pneumonia, bacteria, fungi or viruses infect the air sacs of the lungs, triggering an inflammatory response that leads to mucus and fluid in the airways, explains the National Heart, Lung and Blood Institute.
Chronic bronchitis, a form of chronic obstructive pulmonary diseases, is a leading cause of persistent, productive cough. The condition develops with protracted irritation of the lungs. The American Lung Association reports that most cases of chronic bronchitis occur due to cigarette smoking. Ongoing inflammation of the airways provokes a marked increase in mucus production, leading to a chronic productive cough.
Paroxysmal cough describes an episodic cough characterized by periods of severe, nearly continuous coughing often described as a "coughing fit." Pertussis, or whooping cough, remains an important cause of paroxysmal cough. The bacterium Bordetella pertussis causes the illness, which begins with symptoms similar to a head cold. Approximately one to two weeks into the illness, paroxysmal coughing develops. Coughing episodes frequently prove so severe that the patient develops blue discoloration of the face and lips caused by lack of oxygen. Whooping cough proves most dangerous for infants and young children, reports the Centers for Disease Control and Prevention. With vaccines, Pertussis is usually a preventable disease.
Other possible causes of paroxysmal cough include asthma, tuberculosis and bronchiectasis, a condition in which the airways widen after sustaining permanent damage. Mucus collects in the dilated airways, provoking paroxysmal coughing. Cystic fibrosis is among the leading causes of bronchiectasis in the United States, according to the National Heart, Lung and Blood Institute.