Evaluation and Management of Chronic Loss of Taste and Smell

Initial Diagnostic Approach

The American Academy of Otolaryngology recommends beginning with objective psychophysical testing using validated instruments (UPSIT or Sniffin'Sticks) combined with rigid nasal endoscopy to differentiate between conductive and sensorineural causes, as patients typically cannot accurately assess their own degree of impairment 1, 2
A detailed history should be obtained, focusing on onset timing, duration, and temporal relationship to viral infections, as post-viral olfactory loss accounts for 20-25% of specialist clinic presentations 3, 4
The European Rhinologic Society suggests documenting associated symptoms, including nasal obstruction, rhinorrhea, or flu-like illness, and noting predisposing factors such as nasal polyps, asthma, and advancing age, which increase the risk of greater smell loss 1, 2, 5

The American Rhinologic Society recommends using validated smell tests, such as UPSIT or Sniffin'Sticks, which have high test-retest reliability and take 4-25 minutes to administer 1, 2, 6
Patients are commonly unaware of their impairment severity, making objective testing mandatory rather than optional, with a strength of evidence level of high 1, 2

The Centers for Disease Control and Prevention recommends performing COVID-19 testing in all patients with sudden-onset taste/smell loss, especially during pandemic periods, as olfactory dysfunction may be the sole presenting symptom 7, 4
Recovery occurs in 44-73% of COVID-19 patients within the first month, though some develop persistent dysfunction, with a moderate strength of evidence 7, 8

The American Academy of Otolaryngology suggests ordering CT and MRI of skull base and brain only when psychophysical testing severity does not correlate with endoscopic findings, raising suspicion for occult sinonasal or skull base tumor, with a low strength of evidence 1, 2

The European Rhinologic Society recommends treating sinonasal inflammatory disease with appropriate medical or surgical management, and starting olfactory training immediately and continuing for a minimum of 3-6 months, with a moderate strength of evidence 5
Referring patients to a registered dietitian for counseling on flavor enhancement, additional seasoning, and expanding dietary options is also recommended, with a low strength of evidence 5

The American Academy of Otolaryngology recommends re-evaluating patients at 1 month, 3 months, and 6 months after initiating treatment, and referring to an otolaryngologist or specialized smell/taste clinic if no improvement after 3-6 months, with a moderate strength of evidence 5
Repeat psychophysical testing at follow-up visits to objectively document changes, with a high strength of evidence 1, 2

Patients should be referred to validated resources for proper olfactory training technique, as recommended by the European Rhinologic Society, and such resources include websites like www.fifthsense.org.uk 9, 10, 11

Recovery occurs in 44-73% of patients within the first month, with complete resolution seen in 13% and partial resolution in 14% of patients, and the mean time to improvement is 7.2 days 12
Recovery typically takes place within a few weeks, but longer timeframes are possible, with one case series showing recovery by day 17 in one patient, while others had persistent dysfunction requiring ongoing management 12, 13
The American Academy of Otolaryngology recommends that patients with persistent dysfunction be referred to an otolaryngologist or specialized smell/taste clinic if no improvement occurs after 3-6 months of olfactory training, although the exact recommendation is not provided in the given citations, the European Rhinologic Society may have similar guidelines 11, 14

The European Rhinologic Society may recommend against relying on patient self-assessment of olfactory function severity, as objective testing reveals much higher rates of dysfunction, although the exact recommendation is not provided in the given citations 10, 11