3.    Gastroesophageal Reflux Disease (GERD)

GERD is a condition of the stomach and esophagus caused by stomach acid backing into the esophagus due to a weak valve. While GERD’s main symptom is severe heartburn, chronic cough, chest pain and wheezing are also common symptoms. While it’s not given the same attention as other causes on this list, GERD is a fairly common cause of chronic cough.

4.    Respiratory Tract Infection

Coughing is most associated with colds, influenza and other respiratory tract infections, typically accompanied by stuffy nose, fever, body aches and fatigue. Typically these symptoms last for days, unless the infection causes pneumonia, which can be caused by both bacteria and viruses. Persistent cough that produces green- or rust-colored phlegm is one of the main symptoms of the illness, along with fever, chills, chest pain, weakness and nausea.

If you have a cold, over-the-counter medicines should help make you comfortable until it clears up on its own, although your cough can outlast the other cold symptoms while the air passages in your lungs remain sensitive and inflamed. Pneumonia is treated with antibiotics and generally clears up within two to three weeks, although, again, the cough can linger much longer.

5.    Air Pollution

Living in or traveling to an area with air pollution can cause a persistent cough. Even short-term exposure to fumes and air pollution (e.g., diesel exhaust) can result in cough, phlegm and lung irritation and can exacerbate other symptoms of allergies or asthma. Air pollution doesn’t just occur outdoors: Mold spores found in and around your home can cause wheezing and coughing when inhaled.

In the aftermath of Hurricane Katrina, there were so many reports of persistent cough when residents returned that the term “Katrina cough” arose. This cough was believed to have stemmed from mold caused by homes flooding, combined with the construction dust that filled the city during the rebuilding process.

6.    Acute Bronchitis

Bronchitis typically rears its ugly head on the heels of a cold, where the patient suddenly develops a hacking, wet cough -- a result of passageways in the lungs becoming infected and inflamed. The wet cough is typically accompanied by fever, chills, aches, sore throat and other flu-like symptoms.