Patients with decreased sense of smell may have symptoms of chronic simple rhinitis, chronic hypertrophic rhinitis, drug-induced rhinitis, atrophic rhinitis and so on. 1. Chronic simple rhinitis: chronic simple rhinitis is a kind of rhinitis, which refers to the chronic inflammation that occurs in the mucous membrane and submucous layer of the nasal cavity, due to the stimulation of the nasal mucous membrane by inflammation may cause nasal congestion, snotty, and decreased sense of smell, etc., and some of the patients are accompanied by coughing, phlegm, headache and other complications. 2. Chronic hypertrophic rhinitis: chronic inflammation of the nasal cavity characterized by limited or diffuse hyperplasia and hypertrophy of the mucosa, submucosa, and even bone. Clinical characteristics of nasal congestion, mostly persistent, occlusive nasal sound, smell loss, such as the posterior end of the turbinate compression of the Eustachian tube pharyngeal orifice, there may be tinnitus, hearing loss; can also cause chronic pharyngolaryngitis; headache, dizziness and other symptoms. 3. Drug rhinitis: rhinitis caused by systemic or local use of drugs, clinically refers to the local use of drugs caused. Mainly manifested as bilateral persistent nasal congestion, decreased sense of smell, increased nasal secretion symptoms. 4. Atrophic rhinitis: atrophic rhinitis is a slow-developing chronic inflammatory disease of the nasal cavity, due to the dryness and atrophy of the nasal mucosa, the nasal cavity is enlarged, and the patient may have a reduced sense of smell, a large number of yellowish-green pus crusts formed in the nasal cavity, nasal congestion, nosebleed and so on. In addition, some patients with allergic rhinitis also have symptoms of decreased sense of smell, if the symptoms of decreased sense of smell, it is recommended that the patient consult a doctor for examination in a timely manner, to clarify the cause of the disease after targeted treatment.