When we smoke and for all the years that we smoked each and every puff on a cigarette destroyed the cilia, or tiny little hair-like projections lining our respiratory tract.  These cilia are responsible for filtering out all the impurities we breathe on a daily basis.  They line our nose and reach all the way down into our lungs.  When we quit smoking, the first thing, essentially to start repairing itself, is the respiratory tract......and as soon as we take the last puff, the cilia start to regenerate themselves.  In some people these cilia grow back faster than others. 

Coughing is a natural byproduct of the reemerging cilia.  It makes no difference how long or how much you smoked, the rate of regrowth can and is different in most of us.  The faster the cilia grow, the more likely we are to cough lots in the first weeks of a quit.  Our bodies are healing and our lungs are clearing themselves of all the toxins and impurities. 

But whether your cilia grow back rapidly and we cough lots or slowly and we cough little....any cough lasting more that a few weeks and is persistant and is accompanied by pain and or fever, should be checked by a qualified physcian.  The body heals remarkedly fast but smoking often covers a variety of other illnesses and conditions and a lingering cough should not always be associated with quitting smoking.  It's a great idea for any of us quitting to have our lungs checked out afterwards.  It really does help with peace of mind.