pathophysiology - What is the cause of dry cough?

I first thought this question in the case of

• the cause of dry throat after 3-day recovery of dry cough?

but then I realised that the cause of dry cough can be a general thing.

Assume the person had three days recovery of dry cough under Montelukast and codeine (tablet). He visited gym with little cardiotraining just after the catarrhal inflammation ended (no yellow mucose from throat during mornings anymore. Just after the training, he felt dry throat after very weak coughs (no codeine medication when doing sport).

I am not sure if the dry throat is caused by

• atrophy of the membranes in the throat


• or dry cough by Acute respiratory viral infection (possibly through reflex arch; cannot be sure this because no codeine medication).

Let's assume that the dry throat is caused by dry cough (although weak) because virus particle can pass easily the scarring of the mucose membrane in the throat.

I think the atrophy of the membranes in the throat are NOT felt as dry. Dry cough of the infection is felt shortly as dry. The sympaticus activity clears the mucose membrane from the throat which alleviated the pain and also irritated the scarring. Acute virus infection stimulates serous inflammation (as described here) which in the scarred tissue is felt once again as catarrhal inflammation.

So I think the cause of dry cough is catarrhal inflammation. The localisation of the inflammation is essential to determine the type of inflammation, I think.

What is the cause of dry cough?

Answer

Cough-variant asthma is a common cause for a non-productive dry cough. Asthma is not a single condition involving bronchospasm and with associated wheezing - there is a variant that is primarily or only coughing.

There are different inciting factors that bring on symptoms cough-variant asthma. Most commonly they are exercise-induced, cold-induced, allergy-induced, or quite commonly it happens following a viral respiratory infection (post-viral-URI). Symptoms can be acute (exercise or cold) lasting minutes, or chronic lasting days-weeks or even indefinitely.

The pathophysiology for each is different. The latter 2 are inflammatory processes, as you mentioned, each a little different (hypersensitivity versus residual infectious inflammation). I am a little uncertain about the mechanisms you described, and I am not sure the correct thing to focus on is scarring. I would focus primarily on the inflammation. Inflamed mucous membranes are extremely sensitive, reacting to even dry or cold air.

Using a long-term steroid inhaler is a preferred method of handling chronic cough-variant asthma, as it reduces airway inflammation.

There can be other causes of cough such as postnasal drip, chronic rhinitis, sinusitis, or gastroesophageal reflux disease (GERD or heartburn).