Cough is a protective reflex of the human body that helps to propel mucus, infected material, or sometimes the rare foreign body out from the throat and lungs. It can be voluntary (under your control), or involuntary (which is sudden or spontaneous). When a cough lasts longer than 8 weeks in adults or 4 weeks in children, it is known as chronic cough.  

Chronic cough (also known as persistent cough) impacts the quality of your life. While a chronic cough is not a disease, it might be the cause of an underlying or a serious health condition, such as a heart problem or a lung disease. 

Common causes include asthma, allergies, gastroesophageal reflux disease (GERD), or bronchitis (inflammation of the lining of your bronchial tubes, which carry air to and from your lungs). 

Chronic cough may be dry or with mucus. Chronic cough can interrupt your sleep and can also cause vomiting, lightheadedness, and even rib fracture in certain cases. 

Causes of Chronic Cough

It has traditionally been understood that chronic cough in adults could be due to the following causes, alone or in combination:

1. Asthma. Asthma is a chronic condition in which a person's airways become inflamed and narrow, making it difficult for the person to breathe. Asthma can be mild or severe, where it can hamper daily activities. In some cases, it can also be life-threatening. 

The most common symptoms of asthma include difficulty in breathing, chest pain, coughing, and wheezing (whistling noise while breathing, which occurs due to air being forced through a narrower passageway). 

Asthma-related cough can come and go with the seasons changing. This occurs after an upper respiratory tract infection (URTI) and can become worse when you are exposed to cold air or certain chemicals or fragrances. Cough is the main symptom in the cough-variant type of asthma. 

2. Gastroesophageal Reflux Disease (GERD). In this condition, the acid from the stomach flows back into the esophagus (a tube connecting stomach and throat). 

The constant irritation caused due to acid can lead to chronic coughing. GERD and coughing operate in a vicious cycle as chronic coughing leads to worsening of GERD, which in turn, stimulates chronic cough. 

3. Postnasal Drip. When your nose or your sinuses produce extra mucus, it drips down from the back of the throat and can trigger a cough reflex. This condition is known as postnasal drip. 

This causes constant irritation in the throat and a cough, which is called upper airway cough syndrome (UACS).

4. Infection. After pneumonia, flu, cold, or any other infection of the upper respiratory tract, a cough can linger. One of the most common causes of chronic cough is whooping cough (also known as pertussis, which is a serious, contagious respiratory tract infection caused by bacteria).

Fungal infections caused by tuberculosis (TB) or non-tuberculous mycobacteria can also cause a chronic cough. 

5. Chronic Obstructive Pulmonary Disease (COPD). Obstruction in the airflow from the lungs is known as COPD and it includes asthma, chronic bronchitis, bronchiolitis, and emphysema. Chronic bronchitis can cause cough with colored sputum whereas, emphysema (a disease in which air sacs in your lungs get damaged and the lung tissue loses elasticity, leading to enlargement of air sacs, which causes difficulty in breathing and cough) causes shortness of breath. 

COPD is mainly seen in current or former smokers. 

6. Blood Pressure Drugs. A group of medicine called ACE inhibitors (Angiotensin-converting enzyme inhibitors) which are commonly prescribed for high blood pressure and heart failure are known to cause a chronic cough in some people. 

7. Smoking. If you smoke regularly, you are most likely to cough often. Coughing is a way by which your body forces out substances and chemicals that enter your throat and lungs due to tobacco use from smoking.

8. Less common causes of chronic cough are:

  • Aspiration of food or foreign particles

  • Exposure to environmental irritants

  • Dilated or damaged airways

  • A very small part of the airways in the lungs are inflamed

  • Cystic fibrosis (a hereditary disease that affects the lungs and digestive system)

  • Lung cancer

  • Inflamed airway other than asthma

  • Chronic scarring of the lungs due to an unknown cause

If the symptoms of your cough do not get better in about 2 weeks, it is best to consult your ENT specialist.

Disclaimer: This article is written by the Practitioner for informational and educational purposes only. The content presented on this page should not be considered as a substitute for medical expertise. Please "DO NOT SELF-MEDICATE" and seek professional help regarding any health conditions or concerns. Practo will not be responsible for any act or omission arising from the interpretation of the content present on this page.