Overview
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.
Eligibility
Inclusion Criteria:
- Olfactory dysfunction caused by COVID-19
- Hyposmia (16.25-30.5) or anosmia (\<16) with or without parosmia assessed by TDI test with Sniffin Sticks performed in the Unit for Sense of Taste and Smell
- \> 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
