What is post nasal drip (pnd)? post-nasal drip occurs due to the excessive mucus production by the sinuses the surplus builds up at the back of the nose and the throat causes of post nasal drip it is triggered by sinusitis (inflammation of the sinus cavities), rhinitis (inflammation of the nasal mucosa), acid reflux (gerd) or allergies. Acid reflux symptoms post nasal drip. It could be due to a cold, allergies, or even acid reflux what is post-nasal drip? post-nasal drip starts in your sinuses, which are air-filled cavities located under the bony base of the cheeks.
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