Coughing from time to time helps clear particles and secretions from the lungs and helps to prevent infection. However, sometimes a cough can become a chronic condition. A chronic cough is defined as a cough that lasts for eight weeks or longer.

CAUSES OF CHRONIC COUGH — The most common causes of chronic cough are smoking, postnasal drip, asthma, and acid reflux from the stomach. These 4 causes are responsible for up to 90 percent of all cases of chronic cough. Less common causes include infections, medications, and lung diseases.

Postnasal drip — Postnasal drip occurs when secretions from the nose drip into the back of the throat. These secretions can irritate the throat and trigger a cough. Postnasal drip can develop in people with allergies, colds, rhinitis, and sinusitis.

Signs of postnasal drip include a stuffy or runny nose, a sensation of liquid in the back of the throat, and a feeling you need to clear your throat frequently. However, some people have so-called “silent” postnasal drip, which causes no symptoms other than a cough.

Asthma — Asthma is the second most frequent cause of chronic cough in adults, and is the leading cause in children. In addition to coughing, you may also wheeze or feel short of breath. However, some people have a condition known as cough variant asthma, in which cough is the only symptom of asthma.

Asthma-related cough may be seasonal, may follow an upper respiratory infection, or may get worse with exposure to cold, dry air, or certain fumes or fragrances.

Acid reflux — Acid reflux (GERD) develops when acid from the stomach flows back (refluxes) into the tube connecting the stomach and the throat (the esophagus). Many people with cough due to acid reflux have heartburn or a sour taste in the mouth. The presence of this acidic material can lead to chronic irritation and coughing.

Other causes —

Respiratory tract infection — An upper respiratory infection such as a cold can sometimes cause a cough that lasts more than eight weeks. This may be due to postnasal drip (as described above), or to irritability in the airways that developed as a result of the infection.

Use of ACE inhibitors — Medications known as angiotensin converting enzyme (ACE) inhibitors, which are commonly used to treat high blood pressure, cause a chronic cough in up to 20 percent of patients. The cough is usually dry and hacking. Switching to another medication often improves the cough over the course of one to two weeks.

Chronic bronchitis — Chronic bronchitis is a condition in which the airways are irritated, causing you to cough, sometimes raising phlegm. Most people with chronic bronchitis are current or past smokers.

Lung cancer — Although lung cancer can cause coughing, very few people with a chronic cough have lung cancer. Cancer is possible, however, especially if you are a smoker and your cough changes suddenly, you begin to cough up blood, or if you continue to cough more than one month after quitting smoking.