Olfactory hypersensitivity is increased sensitivity to olfactory odor stimuli and is a clinical manifestation of olfactory disorder olfactory nerve is the nerve fiber of olfactory epithelium across the sieve plate to the olfactory bulb. The ability to smell is a characteristic of olfactory cells in the nasal mucosa. Injury to the nasal mucosa, olfactory bulb, olfactory filaments or central nervous system connections may affect the sense of smell. Clinical manifestations include hyposmia, olfactory loss, olfactory deficit, olfactory inversion, phantom sniffing and increased sensitivity to olfactory stimuli. The main symptoms of olfactory hypersensitivity that are easily confused are as follows 1. Hyposmia: Olfactory impairment is often manifested as reduced sensitivity to smell and odor stimuli. 2.Loss of smell: Severe acquired olfactory impairment is manifested by loss of response to olfactory odor stimuli. 3. Olfactory deficit: congenital olfactory deficit, manifested as no response to olfactory stimuli. 4. Olfactory inversion: manifested as misplaced response to olfactory odor stimuli, but not accompanied by olfactory acuity impairment. 5.Phantom smell: There is no objective smell and odor stimulus, but the patient smells an indescribable and usually unpleasant odor.