The onset of the disease is mainly due to bacterial infection. The pathogenic bacteria include common cold bacillus type I, Staphylococcus, streptococcus, and diplococcus pneumoniae, etc. Mixed viral infection is possible, too. The mucosa of epiglottic against the tongue surface is relatively flaccid. Therefore swelling is especially severe in this part, which may increase to five to six times of the normal size. In severe cases, the epiglottic swelling is as large as a ball, with edema of the interstitial tissue and increased infiltration of the inflammatory cell. Abscess may form in some patients. General allergic reactions sometimes may lead to heavy edema of epiglottis and the aryepiglottic fold, which develop into secondary infection to give rise to the disease.

Because the disease may develop into severe swelling of epiglottis to cause the emergent symptom of obstruction of air passage, TCM categorizes it into "Jihoufeng" (acute laryngeal infection). When pathogenic factors invade the lung, the pathogenic heat will rise to attack the pharyngolarynx, causing local epiglottic qi stagnation and blood stasis to result in the swelling and obstruction. This is the main pathogenic factors and pathogenesis of epiglottiditis.