Why does sinus drainage irritate vocal cords?

Sinus drainage can irritate the vocal cords due to the presence of mucus and inflammatory substances that accompany sinus congestion and infection. When mucus drains down the throat, it can cause irritation and inflammation of the larynx, leading to symptoms such as hoarseness or a scratchy throat. Additionally, post-nasal drip can result in increased throat clearing, which places further strain on the vocal cords. This irritation disrupts normal vocal function and can lead to discomfort or vocal fatigue.