An interventional study of Smell training in Hyposmia, COVID-19 and Parosmia, sponsored by Université du Québec à Trois-Rivières. Recruiting at 1 site in Canada. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-31.
Sponsored by Université du Québec à Trois-Rivières · Not applicable, Interventional, and Treatment
Olfactory dysfunction is a defining symptom of COVID-19 infection. Studies have demonstrated improved olfaction in patients with post infectious olfactory dysfunction after an olfactory training (OT). The aim of this study is to assess the clinical outcomes of olfactory training (12 weeks) therapy in the treatment of persistent olfactory dysfunctions after COVID-19. Specially, we aim to compare the effectiveness of two different olfactory training (different odors).
A group will train themselves with 4 scents (rose, orange, clove and eucalyptus) and another group with 4 different scents (cheese, coffee, strawberries and lemon). Olfaction sensory evaluation will be performed by using different olfaction tests (Sniffin' Sticks and UPSIT) and complete questionnaires to assess olfactory perception and particularly parosmia and phantosmia.
Patients who meet the criteria, who have agreed to participate in this research project and sign the consent form will be placed in one of the following two groups:
● Experimental group (olfactory training)
Initial meeting: Each participant will be asked for a session of approximately 1:30 h which will take place in a ventilated room in the laboratory of Dr. Johannes Frasnelli at UQTR. During the hour preceding this evaluation, subjects will be asked not to smoke, eat or drink anything other than water and not to wear perfume. A research assistant will be responsible for completing the various tests. During this meeting, the following tests will be done:
Treatment (12 weeks): Following the initial meeting, patients can begin training:
■ Participants will bring their training kit with them following the olfactory evaluation.
Final meeting: After 12 weeks of treatment, an appointment will be scheduled with the participant. The olfactory evaluation will be done as described in the initial meeting. During the hour preceding this evaluation, subjects will be asked not to smoke, eat or drink anything other than water and not to wear perfume. A research assistant will be responsible for administering the various tests. During this meeting, the following tests will be done:
180 studies on the registry are indexed under Anosmia; 45 are open to participants now.
This study's planned enrollment of 70 is above the median of 60 across 114 interventional studies indexed under Anosmia.
Browse Anosmia studies →Université du Québec à Trois-Rivières is the lead sponsor of 40 studies on the registry; 8 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
For 12 weeks, morning and evening, smell four odors namely eucalyptol, phenyl ethanol, Orange, and eugenol, for a total of five minutes per session.
Other: Smell training
For 12 weeks, morning and evening, smell four odors namely coffee aroma, cheese aroma, strawberries, and limon, for a total of five minutes per session.
Other: Smell training
For 12 weeks, morning and evening, smell four different odors or four odorless substances for a total of five minutes per session.
Also known as: Chemosensory training group
Changes from baseline in olfactory score on the University of Pennsylvania Identification Test (UPSIT) [ Time Frame: Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
The UPSIT includes 4 odor-impregnated booklets that contain 10 forced-choice multiple choice questions each for participants to scratch-and-sniff to identify various odors and is a commercially available test. Normosmia is defined as ≥34 for males and ≥35 for females, and a change of 4 points or more from baseline indicates a clinically meaningful result.
Time frame: Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
Changes from baseline in olfactory score on the Sniffin's Sticks test
Sniffin' Sticks test and Taste strips: Sniffin' Sticks test (Burghardt®, Wedel, Germany) is a psychophysical test. It allows semi-objective assessment of the patient's olfactory performance by means of 3 subtests: threshold test, identification test and discrimination test. The Sniffin' Sticks Olfactory Test Kits contain pen like bodies as, for example, in pens used to write on flipcharts or whiteboards.These pen-like bodies, however, contain a fibre stick which is filled with scents. For testing, the cap should be removed so the patient can smell on the tip of the pen.
Time frame: Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
n-house test for chemosensory dysfunction (TMSC)
The TMSC is a 55-item questionnaire evaluating the three chemical senses: olfaction, taste and the trigeminal sense. First, questions with a 10-point visual analog scale make a subjective self-assessment of each of the three senses. Multiple-choice questions establish the precise characteristics of the dysfunctions of each of the senses if they are present. Secondly, a psychophysical test is administered remotely using substances typical of North American cuisines. Substances are first sniffed (peanut butter, jam, vinegar, coffee) then tasted (peanut butter, jam, salt water (1 tsp/250mL), sugar water (3 tsp/250mL)). The perceived intensity of each of the substances is reported each time on a visual analogue scale of 10 points.
Time frame: Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
Parosmia and phantosmia assessment test
This test has a first part with four questions that aim to assess the presence of parosmia or phastosmia. Patients who have reported parosmia or phantosmia will be asked to complete a second part with six questions focusing on the quality of their olfactory distortion.
Time frame: Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
The abridged version of the Questionnaire of Olfactory Disorders - Negative Statements (sQOD-NS)
The sQOD-NS is a validated questionnaire that measures the quality of life specific to olfactory functions. The questionnaire measures 7 items with a 4-point Likert scale.
Time frame: Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
Nasal Obstruction Symptom Evaluation (NOSE)
A visual analog scale (scale from "not a problem" to "severe problem") is used by participants to assess their nasal obstruction. The duration of this test is approximately 2 minutes.
Time frame: Measurement will be taken at time zero (pre-intervention)
Started May 2022 (actual). Primary completion is estimated for Sep 2027, 64 months after the start.
Of 50 non-industry interventional studies with no phase under Anosmia, half reached primary completion within 28 months of starting (the median), counting those still running; a quarter within 14 and three quarters within 37. This study's planned 64 months is above that.
Counting every sponsor, half of 50 studies reached it within 28 months; a quarter within 14 and three quarters within 37.
How these figures are worked out, and which studies are left out of them.
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Université du Québec à Trois-Rivières