Hello.
Thank you for asking at HCM.
I went through your nephew's history.
I assume that apart from this, he does not have any other health complaints.
Were I treating him, I would suggest to take a combination of
montelukast &
levocetirizine daily at evening for 14 days.
If he has any of the complaints like regurgitation, nausea,
vomiting or burning in chest, especially after spicy meals, I would also suggest
antacid like
omeprazole before meals for 14 days.
I would suggest you to make sure that there are no cold air currents directed at his nose/face (such as air conditioner, open window, etc) in the bedroom. Cold, dry air currents directly entering the nose may also cause coughing at night.
Hope this will be helpful to you.
Wish your nephew the best of the health.
Regards.