Postnasal drip, asthma, and acid reflux from the stomach are responsible for about 90 percent of all cases of chronic cough.
Postnasal Drip Postnasal drip can develop in people with allergies, colds, rhinitis, and sinusitis, says Taliercio. When secretions from the nose drip or flow into the back of the throat from the nose, the resulting irritation can trigger cough.
Signs of postnasal drip include a stuffy or runny nose, a sensation of liquid in the back of the throat, and a feeling of needing to clear the throat frequently. About 20 percent of people have silent postnasal drip, which causes no symptoms other than a cough.
Respiratory viral infections, including long COVID, and bacterial sinus infections can also cause postnasal drip and chronic cough.
Asthma Asthma is a frequent cause of chronic cough in adults and is the leading cause in children, says Taliercio. “So traditionally, we think of patients with asthma as experiencing episodic breathlessness, chest tightness, wheezing, and cough, with the symptoms classically varying over time and intensity,” she says.
Some people have something called cough variant asthma, in which cough is the only symptom of asthma, says Taliercio. “Most of the time, the cough isn’t productive, but not always,” she says.
Asthma-related cough may come on seasonally, may follow an upper respiratory infection like COVID-19, or may get worse due to cold and dry air, exercise, fumes, or fragrances.
Acid Reflux Gastroesophageal reflux and gastroesophageal reflux disease occur when acid from the stomach flows back into the esophagus, the tube connecting the stomach and the throat, according to the National Institute of Diabetes and Digestive and Kidney Diseases. Many people with chronic cough due to acid reflux have heartburn or a sour taste in the mouth.
Eosinophilic Bronchitis Less common and more curable than asthma, nonasthmatic eosinophilic bronchitis is a special type of inflammation in the airways that can cause a chronic cough. This happens in people who don’t have evidence of asthma but whose phlegm or airways contain cells called eosinophils (white blood cells produced by the immune system in response to different factors including allergic reactions).
Certain Blood Pressure Medications Angiotensin converting enzyme (ACE) inhibitors, which are commonly used to treat high blood pressure, can cause a chronic cough (usually dry), says Dowdall.
Chronic Bronchitis Chronic bronchitis usually occurs with current or past smokers and is sometimes called smoker’s cough. Typically, the cough is worse in the morning, when the body is trying to clear the airways of mucus and irritants that have built up overnight.
Lung Cancer Very few people with a chronic cough have lung cancer, but it can happen, and the risk is higher in current and past smokers. Possible signs are coughing up blood, a change in the cough, or continuing to cough more than one month after quitting smoking, according to the American Cancer Society.
Bronchiectasis People who have had severe or recurrent respiratory infections can have damage to their airway walls and permanent dilation of the bronchi (the tubes that carry air from the windpipe to the lungs), called bronchiectasis. This decreases the ability to clear secretions and can cause a chronic cough.
Habit, or Nervous Cough This is a habitual cough that continues even though the underlying cause appears to be gone. But it’s important to keep in mind that the cause of a cough can change over time, says Taliercio. “Even though your cough was due to one thing a couple of years ago, there could be another underlying reason for it now,” she says.
Cough Hypersensitivity Syndrome With this condition, excessive coughing is caused by relatively mild stimuli or irritants, says Taliercio. “This is like a nerve-induced cough; it’s not very common, but it’s more likely to occur in people who cough for years or even decades,” she says.