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What Is The Cause Of Chronic Or Prolonged Cough?

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Dr Eng Cern Gan

September 18th, 2019· 5 min read

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A chronic or prolonged cough refers to one that lasts eight weeks or longer in adults. It can be more than just an annoying ailment, interrupting sleep and leaving you feeling unrested and exhausted. Chronic cough can be highly uncomfortable and interfere with one's daily activities, work and even sleep. When severe, it may result in vomiting, chest pain and injury to the respiratory tract.

Let's take a close look at the causes and symptoms of a chronic cough, treatments available, and when to consult a doctor.

Symptoms often associated with chronic cough

Signs and symptoms of chronic coughing include:

  • Runny or stuffy nose
  • The sensation of liquid running down or getting stuck to the back of your throat
  • Frequent throat-clearing
  • Sore throat
  • Hoarse voice
  • Wheezing and shortness of breath
  • Blood in the saliva or sputum

man coughing

Causes of chronic coughing

Cough is most often classified based on its duration:

Acute – Coughing that lasts 3 weeks or less
Subacute – Coughing that lasts between 3-8 weeks
Chronic – Persistent coughing for more than 8 weeks [1]

Acute coughing is usually due to viral infections of the upper respiratory tract infection such as flu. You can often recover from acute coughing without many complications. Some of the more common causes of acute cough include [2]:

  • Common cold
  • Sinusitis
  • Acute bronchitis
  • Exacerbation of chronic obstructive pulmonary disease (COPD)
  • Influenza
  • Pneumonia
  • Pertussis

sick man sneezing

Chronic coughing can also be a symptom of more serious problems:

  • Postnasal drip refers to when excess mucus produced flows back down the back of your throat and triggering your cough reflex.
  • Asthma-related coughing is dependent on circumstances such as preexisting upper respiratory tract infection, cold air, dust or animal fur, presence of chemicals or fragrances, strenuous activity and even excitement.
  • Gastroesophageal reflux disease (GERD) is characterised by stomach acid flowing back and forth through the oesophagus. The acids can irritate and damage throat tissues. GERD can be a vicious cycle when severe coughing triggers a gag reflex, causing more acid to reflux.
  • Infections. A cough can persist even after pneumonia, flu or other infections of the upper respiratory tract have been treated. A common but lesser-known cause of chronic coughing is pertussis or a.k.a. whooping cough. Fungal infections of the lung, tuberculosis (TB) or infections by other pathogens can also cause chronic coughing.
  • Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease that causes the airflow to the lungs to be obstructed. It can take either form: chronic bronchitis or emphysema. Chronic bronchitis can cause you to cough up coloured sputum while emphysema causes you to feel short of breath as air sacs in the lungs become damaged.

Less commonly, chronic cough may be caused by:

  • Bronchiectasis (damaged and dilated airways)
  • Bronchiolitis (inflamed airways of the lung)
  • Cystic fibrosis
  • Laryngopharyngeal reflux (stomach acid flowing up the digestive tract)
  • Lung cancer
  • Nonasthmatic eosinophilic bronchitis (airway inflammation not caused by asthma)
  • Sarcoidosis (collections of inflammatory cells in different parts of your body, most commonly the lungs)
  • Idiopathic pulmonary fibrosis (chronic scarring of the lungs due to an unknown cause)

A study in Singapore showed that the most common causes of cough in Singapore are postnasal drips, acid reflux from the stomach and asthma. Studies conducted in other countries support the findings - 90% of all chronic coughing studied are due to these 3 conditions. [3]

Risk Factors

Risk factors for developing a chronic cough are:

  • Smoking, both currently and formerly
  • Preexisting allergies
  • Environmental factors like presence of chemicals and pollution
  • People with chronic lung diseases like asthma, bronchiectasis, COPD and lung scarring

Seeing an ENT specialist

Usually, the doctor will take a thorough look into your medical history and perform an ENT examination. Inform the doctor of any medications that you may be taking so he/she may determine if they are the cause of your cough.

You may require a nasendoscopy under local anaesthesia, to assess your nasal cavity, throat and voice box region. The procedure is relatively painless and short and can even be done on children. Depending on your clinical history and the findings of your physical examinations, additional tests like allergy tests (e.g. skin prick test or blood tests) may be performed. A chest X-ray may be required if there is a suspicion of a lung condition.

chest x ray

Treatment for chronic coughing

Treating chronic coughing is dependent on the underlying cause. It usually goes away after the cause has been dealt with. Treatments for chronic coughing can include [4]:

  • Nasal steroid sprays and antihistamines
  • Oral antibiotics, nasal steroid sprays and a nasal douche
  • Acid suppressant medications and lifestyle modifications
  • Inhalants for asthma
  • Stopping smoking
  • Stopping certain medications for drug-induced coughing

Warning signs for serious issues behind your coughing

Consult your doctor if you experience either or a combination of the following:

  • Coughing that lasts longer than 2-3 weeks
  • Thick or coloured phlegm
  • Extreme tiredness
  • Shortness of breath or difficulty in breathing
  • Blood in your phlegm
  • High fever
  • Unexplained loss of weight and appetite
  • Swelling of the face and hives
  • Severe chest pain
  • Exposure to a patient with TB or whooping cough
  • Developed wheezing

man coughing seriously

When should you take cough suppressants?

Sometimes the doctor may not be able to ascertain the cause of your coughing despite extensive checks. As such, he/she may prescribe cough suppressants to reduce the coughing. However, there is no evidence that cough suppressants are effective in treating coughing. They may have potential side effects if taken on a long-term basis too.


Dr Gan Eng Cern is a Consultant Ear, Nose & Throat (ENT) Surgeon with interests ranging across various ENT conditions covering nose problems, sinuses, snoring and Obstructive Sleep Apnoea (OSA).

Read more from Dr Gan Eng Cern in his Q&A here.

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This article was written by Dr Eng Cern Gan and published on Wednesday, 25 January 2017. Human medically reviewed the article on Wednesday, 25 January 2017. The last update was made on Friday, 18 September 2020.

Disclaimer: Opinions belong to the author and not to the platform.

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