**R09.81 — Nasal congestion** is used as a stand-alone symptom code when nasal stuffiness is documented without a specific underlying diagnosis. Common in allergic rhinitis (J30.x), viral upper respiratory infections (J00-J06), or chronic rhinosinusitis (J32.x).
Frequently encountered in primary care, especially during cold/flu season.
Belongs to **Chapter R** — Symptoms, signs.
