Centirizine, Famitodine

 I periodically have a fit of coughing, and take a Cetirizine and Famotidine (in case it's being caused by reflux).  This seems to result in a spate of sneezing, having to blow my nose, and then resolution.

That sequence is actually quite suggestive. It sounds less like the cetirizine is causing the sneezing and more like the episode may be an upper-airway/allergic or irritant process that the medication is helping to settle.

One plausible sequence is: coughing → nasal irritation/secretions → sneezing and nose-blowing → clearing of the irritant/post-nasal material → cough resolves. Cetirizine would fit the allergic/histamine part of that picture. Famotidine is sometimes used when reflux is suspected, although its effect on a cough from reflux isn't immediate or reliably diagnostic.

There's also an interesting possibility that the cough itself is helping mobilize nasal or throat secretions, after which you sneeze and blow your nose and the whole thing clears. In that case the dramatic "resolution" after the sneezing isn't necessarily evidence that either drug directly stopped the cough.

Given that you've described these as periodic fits rather than continuous coughing, I'd pay attention to what precedes them: lying down, eating, a particular room, dust, mold, strong smells, air-conditioning, or mucus in the throat. The pattern could tell you considerably more than the response to a single dose of either medicine.

One caution, though: you previously mentioned being told to stop cetirizine and use levocetirizine instead. I wouldn't routinely substitute cetirizine for the prescribed regimen without checking with your doctor/pharmacist, particularly since you're taking several medications. And if a coughing episode ever comes with significant shortness of breath, wheezing that doesn't settle, chest pain, faintness, or blue/gray lips, that's a different matter and warrants prompt medical attention.

He didn't tell me to stop Centirizine, just no longer every day.  The coughing is predictable a half hour or so after getting up and any time I get cold or a fan in my face.  Of course correcting the last two things does not need medication.

Ah, that changes the picture—and makes your use of cetirizine much more sensible. Your doctor wasn't saying don't use cetirizine; he was taking you off the daily schedule.

The timing you describe is particularly interesting. A cough about 30 minutes after getting up, plus a cough triggered by cold air or a fan blowing on your face, sounds quite compatible with an unusually reactive airway or upper airway. Cold, moving air is a classic mechanical/temperature trigger for coughing, and the morning timing could involve accumulated mucus or drainage overnight.

And I agree about the fan and cold: if the trigger can be removed, removing the trigger beats taking a pill to compensate for it. That's a rather good general rule.

Your "cough → sneezing/blowing the nose → relief" observation also makes me wonder whether the nose and upper airway are substantially involved. The sneezing and nose-blowing may be clearing whatever has accumulated overnight, which would explain why the episode then disappears.

The fact that cold air can provoke it immediately doesn't particularly point toward reflux, either. Reflux could still contribute to the morning episodes, especially after lying down all night, but it wouldn't explain the fan-in-the-face phenomenon nearly as neatly.

So I'd regard your observation as useful information to tell your doctor: "It occurs about half an hour after getting up, and cold air or a fan in my face reliably triggers it; after a coughing fit I often sneeze, blow my nose, and then it stops." That's a much more diagnostically useful description than simply "I cough sometimes."

Dr says because of reflux and bronchial damage earlier, even though I feel no symptom now it is best to combine with Famotidine routinely.

Yes—that makes the overall strategy much clearer. Your doctor is apparently treating two possible contributors to the cough at once: the previously damaged/reactive bronchi and reflux that may be occurring without the usual sensation of heartburn.

The latter is quite real. Reflux does not have to feel like heartburn to irritate the larynx or airways; cough can be the principal—or even only—manifestation. And once airways have been irritated or damaged, they can remain unusually twitchy, so relatively innocuous things such as cold air or a fan can provoke coughing.

That makes your pattern quite coherent:

overnight → possible reflux/secretions → get up → airway becomes active → coughing → nasal secretions/sneezing/blowing → clearing → relief.

And the fan/cold-air episodes are a nice clue toward the airway-reactivity side of the equation rather than reflux.

I also think your doctor's distinction between the two drugs makes sense: famotidine routinely, because he's trying to prevent a contributor you may not feel; cetirizine as needed, because you're using it when the nasal/allergic component seems to be acting up. That's a considerably more rational regimen than simply taking everything every day indefinitely.

One thing I would not infer from the fact that the combination works is that reflux is necessarily the cause of every episode. Your observations suggest there may be several triggers feeding into the same cough reflex. The fact that you can provoke it with cold air is particularly useful evidence of that.