Thank you for your question. The production of this clear phlegm could be due allergic rhinitis or a severe sinus infection. Allergic rhinitis is caused by inflammation of the sinuses due to exposure to an allergen. Common allergens include dust, pollen, and pet hair. This results in increased mucus production which can be coughed up, such as yours. Chronic sinus infections are caused by bacterial infections of the nasal sinus. These can be somewhat difficult infections to treat and can last for months. It is likely that you will need to consult an Ear, Nose, and Throat specialist to determine if you require more investigations or adjust your medications in order to better remedy your symptoms.
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