The most common cause of dumb phlegm is acute congestion and edema of the mucous membrane of the laryngeal cavity due to cold and flu, inflammatory reaction leading to more phlegm, and dumb voice. The first treatment is to take cefradin capsules or roxithromycin with as well as inhalation with budesonide nebulized inhalation treatment. To be strictly silent, eat less raw onion, raw garlic, chili, seafood, tobacco and alcohol, which are spicy and stimulating. If you have chronic laryngitis or vocal cord nodules or vocal cord polyps, first of all, the treatment should be based on clearing the throat and keeping the voice quiet.