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Observational Study
. 2023 Aug 22;59(9):1511.
doi: 10.3390/medicina59091511.

Hyposmia in COVID-19: Temporal Recovery of Smell: A Preliminary Study

Barbara Verro  1 , Giulia Vivoli  2 , Carmelo Saraniti  1
Affiliations
Observational Study

Hyposmia in COVID-19: Temporal Recovery of Smell: A Preliminary Study

Barbara Verro et al. Medicina (Kaunas). .

Abstract

Background and Objectives: Hypo/anosmia is a characteristic symptom of COVID-19 infection. The aim of this study is to investigate the time of smell recovery and to identify a possible order of perception recovery of different odors in COVID-19 patients. Materials and Methods: A prospective observational study was conducted on not hospitalized COVID-19 patients, selected according to eligible criteria. The study was approved by the Ethical Committee. A questionnaire formulated by our team was submitted to patients in order to know the duration of the hypo/anosmia and hypo/ageusia and the order of odor recovery: vanillin (mixed olfactory/gustatory substances), phenyl ethyl alcohol (rosewater) (pure olfactory substances), eucalyptol (mixed olfactory/trigeminal substances), and eugenol (mixed olfactory/trigeminal/gustatory substances). Results: 181 patients were included. Hypo/ageusia and hypo/anosmia lasted on average 10.25 (±8.26) and 12.8 (±8.80) days, respectively. The most frequent odor recovery sequence was: (1) phenyl ethyl alcohol; (2) eucalyptol; (3) vanillin; and (4) eugenol. In COVID-19 patients, hypo/anosmia occurs more often in women and at a young age. Conclusions: This preliminary investigation highlighted novel data: there is a chronological order in perception recovery of different olfactory substances and, therefore, in the restoration of the various sensitive nerve pathways involved in the sense of smell.

Keywords: anosmia; coronavirus; hyposmia; olfaction disorders; olfactory perception.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Questionnaire for COVID-19 patients.
Figure 2
Figure 2
Patients’ selection.
Figure 3
Figure 3
Recovery time for hypo/ageusia.
Figure 4
Figure 4
Recovery time for hypo/anosmia.
Figure 5
Figure 5
Order of odors perception recovery [sequence #1 (phenyl ethyl alcohol, eucalyptol, vanillin, eugenol), sequence #2 (phenyl ethyl alcohol, vanillin, eucalyptol, eugenol), sequence #3 (eucalyptol, phenyl ethyl alcohol, vanillin, eugenol), sequence #4 (vanillin, phenyl ethyl alcohol, eucalyptol, eugenol), and sequence #5 (vanillin, eucalyptol, phenyl ethyl alcohol, eugenol)].
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