The Effect of Olfactory Training in Patients With COVID-19 Induced Olfactory Dysfunction

Summary

Aim: The aim is to investigate the effect of olfactory training with essential oils versus olfactory training with placebo-oils in patients with COVID-19 induced olfactory dysfunction

Study design: The study is a placebo-controlled randomized clinical trial with an intervention group and a control group. The intervention group receive four essential oils with scents of orange, lavender, clove, and peppermint. Patients in the control group receive a fragrance kit, consisting of the same containers, but with fragrance-free oils added. Both groups are instructed to smell each of the four oils for 30 seconds in the morning and evening, over a three-month intervention period. Patients are given a diary in which to record their olfactory training. The nurse or medical student instructing the patients in the training and performing the smell and taste tests is blinded.

Study population: Patients referred to the Unit for Sense of Taste and Smell in the Department of Otorhinolaryngology Head \& Neck and Audiology at Rigshospitalet.

Inclusion criteria:

* Impaired sense of taste and smell following COVID-19 \> 3 months
* Hyposmia (16.25-30.5) or anosmia (\<16) assessed by Sniffin' Sticks Olfactory Test for Threshold, Discrimination and Identification (TDI) performed in the Unit for Sense of Taste and Smell with or without parosmia based on medical history
* \> 18 years of age

Exclusion criteria:

* Cause of hyposmia, anosmia or parosmia other than COVID-19
* Does not read or speak Danish
* Lack of compliance to perform daily olfactory training

Procedures:

\- TDI-test: To assess patients' sense of smell, the TDI-test with Sniffin' Sticks is used, which is a validated tool with normative data.

Questionnaires:

\- 'Taste and Smell Tool for Evaluation' is used to investigate quality of life related to impaired sense of taste and smell.

Conditions

• COVID-19

Interventions

OTHER

Olfactory training with essential oils

Olfactory training twice daily with essential oils from Urtegaarden Aps with scents of orange, lavender, clove and peppermint. The olfactory training is performed every morning and evening, by smelling each of the oils for 30 seconds.

OTHER

Olfactory training with fragrance-free oils

Olfactory training twice daily with fragrance-free oils from Urtegaarden Aps in the same four containers as the intervention group. The olfactory training is performed every morning and evening, by smelling each of the oils for 30 seconds.

Sponsors & Collaborators

• Ditte Gertz Mogensen

  lead OTHER

Principal Investigators

• Vibeke G Backer, Professor · Rigshospitalet, Denmark

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

QUADRUPLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2022-06-29

Primary Completion

2024-04-30

Completion

2025-09-30

Countries

• Denmark

Study Locations