The causes of unilateral nasal congestion include deviated nasal septum, nasal cavernous hemangioma, unilateral sinus infection, and nasal foreign body blockage. 1. Deviated nasal septum: Nasal structure problems cause one side of the nasal cavity is spacious, the other side is narrow, often accompanied by deviated nasal septum, the phenomenon of unilateral nasal congestion. 2. Nasal cavernous hemangioma: cavernous hemangioma consists of blood sinus of different sizes, the tumor is often large, mostly occurs in the natural opening area of maxillary sinus, and is hemorrhagic polyp-like protruding from the middle nasal passage. Nasal bleeding occurs repeatedly, the amount of bleeding varies every time, the bleeding side of the nasal cavity progressive nasal congestion. 3. Unilateral sinus infection: Unilateral sinus infection leads to congestion and edema of the mucous membrane of the inferior turbinate or middle turbinate of one side of the nasal cavity, nasal congestion of one side of the nasal cavity, which is often accompanied by purulent secretion, or nasal mucus with blood, and a sense of facial swelling. 4. Nasal foreign body blockage: Nasal foreign body blockage, such as unilateral nasal cavity with a large number of dry scabs, unilateral nasal congestion or flow of pus and blood snot and accompanied by a bad smell is often considered to be the cause of this factor. Unilateral nasal congestion, should be timely to the regular hospital otolaryngology outpatient clinic, systematic examination of a clear diagnosis, do not self-diagnosis and medication, in order to avoid delaying the condition, resulting in serious adverse consequences.