Mystery cough? 8 possible culprits

Inhaling pollen, dust, pet dander can trigger allergic rhinitis and coughing. Short-term fume exposure can result in cough, phlegm, lung irritation. How to tell acute bronchitis from a more serious condition. Only a doctor can tell for sure what's behind endless hacking.

1. Asthma and allergies
Asthma is a chronic lung disease in which the airways in the lungs are prone to inflammation and swelling.

2. Chronic obstructive pulmonary disease
One condition that can cause a nagging cough is COPD, a lung condition that includes chronic bronchitis and emphysema.

3. Gastroesophageal reflux disease
GERD is an ailment of the stomach and esophagus that occurs when stomach acid backs up into the esophagus due to a weak valve.

4. Respiratory tract infection
Coughing is one of the most common symptoms of colds and flu and other respiratory tract infections. The other symptoms that accompany colds and flu, such as stuffy nose and a fever, are telltale signs that a viral infection is causing your cough.

5. Air pollution
Various pollutants and irritants in the air can cause a persistent cough.

6. Acute bronchitis
If you're on the verge of recovering from a cold and suddenly develop a hacking, mucus-y cough, you probably have acute bronchitis, a condition in which the passageways in your lungs become infected and inflamed.

7. ACE inhibitors
ACE inhibitors are a type of medication used to treat high blood pressure and heart failure. About 1 in 5 people who take the drugs develop a dry cough. In some people, the cough can persist for weeks after they stop taking the medication.

8. Pertussis
Also known as whooping cough, pertussis is a bacterial disease with symptoms that include a slight fever, a runny nose, and, most notably, a violent cough that can make breathing difficult.