Hello,
Mouth breathing is not uncommon in children of this age and it is mostly due to nasal blockage. Nasal blockage can be due to several reasons of most important is Adenoids at this age. Adenoids can be confirmed by a lateral X-ray of
nasopharynx and once confirmed, it must be treated as early as possible (Surgical removal) in order to avoid complications of mouth breathing like high arched palate, teeth abnormalities along with change of facial features.
The nose can also be blocked due to
Rhinitis which is nasal swelling due to allergies, viral/bacterial infections. This rhinitis can also cause
post nasal drip which could be responsible for cough. While you make an appointment for ENT doctor, please give him Flonase
nasal spray 2 puffs once a day, saline nasal spray 2 puffs twice a day, Steam inhalation with some Vicks in it and Chewable tab Claritin once a day for 7 days. This should help relieve the symptoms while being investigated for the root cause.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Omair Choudhry, Otolaryngologist / ENT Specialist