Hi, Noted your history about having difficulty breathing through mouth but not through nose, Investigations like Spirometry, X-ray as suggested by Doctor are normal. This is actually an odd situation wherein your have difficulty only when you breath from mouth and normal for nose. The most probable causes I can think about are as follows: Kissing tonsils that is when the tonsils are enlarged enough to touch each other hence causing breathing difficulty through mouth. Loose and enlarged uvula, pharyngeal folds, excessively large tongue. Hence I would advise you the following in such a situation: Consult an ENT Surgeon for Endoscopy of Nose, throat and ears to see for primary cause and secondary effects. Once the cause is found the treatment can be modulated as per the cause found. Anyways, a person normally does not do any mouth breathing unless required as after exercises, running or heavy work. So not much to worry as such. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. T. Chandrakant, General Surgeon