Cough is a reflex that protects your upper airway from foreign materials and irritants.
However, when persistent, it can be a troublesome symptom. The cause of a chronic or prolonged cough can range from conditions arising from the nose (e.g. Rhinitis and Sinusitis), stomach (e.g. acid reflux from the stomach to the throat, medically known as Laryngopharyngeal reflux or LPR) and lungs (e.g. Asthma, Bronchitis etc) to side effects from medications (e.g. blood pressure medications) and smoking.
If you have a wheeze associated with the cough and do get shortness of breath, you may have asthma and should see a GP or Respiratory Physician. Your GP or Respiratory Physician may perform a lung function test to determine how much air moves in and out as you breathe.
In my practice, the two most common causes of chronic cough are due to a postnasal drip (which can be due to Rhinitis or Sinusitis) and Laryngopharyngeal reflux (LPR).
Postnasal drip refers to a feeling of mucous stuck at the back of the nose and throat. The mucous can cause inflammation of the voice box (larynx). As the voice box is a very sensitive organ, once it is inflamed, it can take weeks to months to recover.
When inflamed, the voice box is prone to causing cough, throat itchiness, frequent throat clearing and phlegm. It is important to treat the cause of the postnasal drip (for Rhinitis - with nasal steroid sprays and antihistamines, for Sinusitis - with a nose wash, nasal steroid spray and antibiotics) to allow the swelling on the voice box to resolve.
If the colour of your phlegm is yellow, brown or green, it may be infected (either from sinusitis or bronchitis) and you may need a course of oral antibiotics.
The voice box can also be inflamed from acid reflux from the stomach (LPR). Common symptoms from LPR include an irritative dry cough, feeling of something stuck in the throat, frequent throat clearing, sore throat and a hoarse voice.
These can be treated by modifying your lifestyle to prevent the reflux from happening and by taking acid suppressant medications.
You can visit an ENT Specialist who will likely perform a nasoendoscopy (small scope through the nose and down to the level of the voice box which is done under local anaesthesia) to help you rule out possible ENT causes.