Persistent cough

Coughing is a normal reflex. It protects our lungs from damage caused by things that irritate our airways, such as smoke or chemicals.

Most people develop coughs because of minor infections like those due to cold viruses.

But when a cough becomes persistent, potentially serious causes need to be ruled out.

There are many possible causes, including:

• cigarette smoking
• lung diseases such as asthma, COPD and bronchiectasis
• sinus disease and nasal drip (an inflammation of the sinuses)
• acid reflux (when acid in your stomach climbs up to the top of your food pipe and irritates your upper airways)
• a group of medicines used to treat high blood pressure (ACE inhibitors such as lisinopril)
• snoring and sleep apnoea
• lung and throat cancer
• a persistent lung infection such as tuberculosis.

When you see your healthcare provider, they will ask you questions about your cough and examine you. In particular they will want to know if you have a moist or a dry cough. 

You may not need further tests. But if you do, they could include:

• a chest x-ray
• lung function tests (also known as spirometry)
• testing a sample of your sputum (mucus or phlegm) to look for bacterial infections.

The treatment for your persistent cough will depend on its likely cause.

Unfortunately, over-the-counter cough syrups or medicines do not usually work.

You may need to try different treatments which can take several months to work. Follow your healthcare provider's instructions, and go back to see them if your cough does not go away.

If your healthcare provider suspects your cough is due to asthma, they may offer you an inhaler. They will also tell you about likely triggers such as pollen, exercise and pets.

If the likely cause is sinus disease, they may get you to try a nasal steroid (such as fluticasone, budesonide or beclometasone) or an antihistamine (such as loratadine or cetirizine).

For reflux, they may treat you with a medication to reduce the amount of acid produced in you stomach, such as omeprazole. 

If the likely cause is a medication, your healthcare provider may get you to try a different medication.

If the cough does not go away, you may need to see a specialist.