Transient fluctuation of smell concurrent with phantosmia has not been reported. Four such cases are presented.

Case 1: A 27-year-old left handed (pathological) female, 7 years prior to presentation, noted constant olfactory hallucinations of dried blood and rotten sour eggs, level 8/10 in intensity.

Results: Without phantosmia: Alcohol Sniff Test (AST): 14 (hyposmia). Brief Smell Identification Test (BSIT): 10 (normosmia). Retronasal Smell Index: 0 (abnormal).

With phantosmia: AST: 1 (anosmia). BSIT: 12 (normosmia). Retronasal Smell Index: 0 (abnormal). Normal 72-hour EEG and MRI.

Case 2: A 19 year old right-handed woman presented with a 4 month history of unpleasant, fruity, rotten phantosmia occurring three times a day, 6-7/10 in intensity.

Results: Without phantosmia: Pocket Smell Test (PST): 3 (normosmia). AST: 30 (normosmia). With phantosmia: AST: 13 (hyposmia). CT scan: normal. MRI: normal.

Case 3: A 40 year old right-handed female presented with ashtray/cigarette phantosmia , occurring 10 times a day, lasting seconds to all day, 10/10 in intensity. Her sense of smell is normal except when the phantosmia is present, during which time it decreases to 70% of normal.

Results: Without phantosmia: BSIT: 11 (normosmia). AST: 30 (normosmia). With phantosmia: AST: 11 (hyposmia). PST: 3 (normosmia). EEG: normal. MRI: few subcortical white matter hyperintensities on flair imaging.

Case 4: A 60 year old right handed male with type 1 diabetes mellitus presented with four months of phantosmia of sweet tobacco, level 8/10 in severity, involves both nostrils, lasting 10 seconds and occurring two times a day. Over time, the hallucinated odor changed to a soapy smell 2-3/10 in intensity.

Results: Without phantosmia: AST: 6 (hyposmia). BSIT: 8 (hyposmia). With phantosmia: AST: 1 (anosmia). PST: 2 (hyposmia). CT scan: normal.

Olfactory ability should be assessed in those with phantosmia, both during and in the absence of hallucinated odors, to detect transient olfactory deficits in order to direct treatment towards this condition.