Chapter 1: Clinical Overview
Viral infections, like colds, flu and COVID, and allergic reactions, like hay fever, are the most common causes of runny and blocked noses:
Inflammation of the membranes (rhinitis) in the nose and sinuses cause fluid/mucous to leak out causing a runny nose (rhinorrhea) and postnasal drip, which may present as a sore throat.
The swollen, inflamed membranes can cause the nose to block, not allowing air to pass through easily.
The mucous can have a thin consistency causing the nose to run or thicken up and block the already narrowed nasal passages.
