Hi, Thanks for asking. I understand your concern. Persistent chronic cough can be due to- - Dry air ways - too hot or cold exposure/drinking less of water/excesive use of nasal spray - following Cold & flu ( viral) air ways remain sore.for long time... the basic symptoms may disappear but cough continues due to sore air ways/ repeated viral affection. - Acid reflux disease (burping, regurgitation & cough ) - Blood pressure medicine - ACE inhibitors can cause it. - history of allergic asthma, bronchitis/ bacterial infection * to pin point the cause co relate his symptoms & get complete blood count done& consult your MD .Depending on his other physical signs he may order more specific investigations followed by treatment. Thanks