constant cough

I have had a chronic cough for months.  When the doctor gives me Benzonatate 200mg 3 times a day the cough does stop but if I stop taking it the cough comes right back.  I am a smoker.  Chest xrays show clear, they have done an MRI, which shows a lower lumbar disc problem.  I am also taking Zyrtec once a day, because allergies affect me greatly.  I always have a dry nasty taste in my mouth.  If I don't take the Benzonatate I start coughing and can even wake up in the middle of a deep sleep to the point that I will begin to vomit and occasionally lose bladder control also.  This has begun to happen during the day too.  I'm scared to take this medicine forever and not know why this is happening, is it masking the symptoms of something else or is this to be expected?  I take the following medications..Benzonatate 200mg (3x day), Zyrtec 10mg (1x day)

[National Jewish]

The most common causes of otherwise unexplained chronic cough are postnasal drip, gastroesophageal reflux (GERD), and asthma.  For you, the most likely cause would be chronic bronchitis from smoking.  However that should not be assumed to be the cause unless you stop smoking and the cough stops.

Suppression of the cough is surely satisfying.  As you have noted this gives no information whatsoever about the cause, be it serious or not.  Having had this cough for months, you should be seen by a lung specialist.

An ongoing cough can also be a side effect of a group of medicines used to treat high blood pressure called angiotensin converting enzyme (ACE) inhibitors.  Neither of the 2 medicines that you are taking are an ACE inhibitor.