HyposmiaNCT06142565
Treatment of Postviral Olfactory Dysfunction
A study testing Nose plug and Regular olfactory training in people with Hyposmia, run by Karolinska Institutet at 1 site in Sweden.
Trial summary
A decreased sense of smell (hyposmia) is often caused by viral infections, such as COVID-19. Today, the only recommended treatment for hyposmia is olfactory training, a time consuming method with limitations in terms of both compliance and effect. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Hyposmia
- What is being tested?
- Nose plug and Regular olfactory training
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 120 participants
- Where
- 1 siteSweden
- Study dates
- 17 Oct 2023to 1 Jul 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 18 - 65 years old
- Physically and cognitively capable of participating in the study
- Having appropriate olfactory screening test scores (hyposmic)
Who cannot join
- Anosmics
- Individuals with other diagnoses that could affect the study results
Trial locations and contacts
1 site in 1 country.
About this study
A decreased sense of smell (hyposmia) is often caused by viral infections, such as COVID-19. Today, the only recommended treatment for hyposmia is olfactory training, a time consuming method with limitations in terms of both compliance and effect. The aim of this study is therefore to evaluate, as well as optimize, a new treatment method for olfactory loss.
Hyposmic participants will be recruited and randomized into two different treatment conditions. One group will do regular olfactory training and the other will do passive olfactory training with scented nose plugs. The training will be conducted in the home of the individual monday through friday for two consecutive months. Subjective and objectvie measures of olfactory problems will be assessed before and after treatment, as well as subjective measures related to quality of live and genereal wellbeing.
- Conditions
- Hyposmia
- Being tested
- Nose plug, Regular olfactory training
- Medical subject headings
- Anosmia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Nose plugDevice
Participants will complete olfactory training with scented nose plugs.
Regular olfactory trainingOther
Participants will complete olfactory training with regular odors found in their home.
| Study group | Role | What they receive |
|---|---|---|
| Olfactory training with nose plugs | Experimental | Participants will complete olfactory training with scented nose plugs. Receives: Device: Nose plug |
| Olfactory training with household odors | Active comparator | Participants will complete olfactory training with odors found in their household. Receives: Other: Regular olfactory training |
What is being measured
The primary outcome is the main question the study is designed to answer.
Objective olfactory function
Does the use of scented nose plugs increase the effect of olfactory training on objective olfactory function compared to regular olfactory training? For this outcome, we will use the standardized Sniffin' Sticks test to assess olfactory function.
Measured: 2 months
Subjective symptoms and social/emotional consequences
Does the use of scented nose plugs increase the effect of olfactory training on subjective symptoms and social/emotional consequences compared to regular olfactory training? For this outcome, we will use the Sino-Nasal Outcome Test (SNOT).
Measured: 2 months
Subjective health
Does the use of scented nose plugs increase the effect of olfactory training on subjective health compared to regular olfactory training? For this outcome, we will use the Self-Rated Health 5 measure and SF-36.
Measured: 2 months
Subjective olfactory function
Does the use of scented nose plugs increase the effect of olfactory training on subjective olfactory function compared to regular olfactory training? For this outcome, we will use the Self-Reported Mini Olfactory Questionnaire.
Measured: 2 months
Subjective degree of suffering from olfactory impairment
Does the use of scented nose plugs increase the effect of olfactory training on subjective degree of suffering from olfactory impairment compared to regular olfactory training? For this outcome, we will use the Questionnaire of Olfactory Disorders - Negative Statements.
Measured: 2 months
Subjective parosmia
Does the use of scented nose plugs increase the effect of olfactory training on subjective parosmia compared to regular olfactory training? For this outcome, we will use the Landis parosmia questionnaire.
Measured: 2 months
Subjective depressive symptoms
Does the use of scented nose plugs increase the effect of olfactory training on depressive symptoms compared to regular olfactory training? For this outcome, we will use the Beck Depression Inventory (BDI).
Measured: 2 months
Subjective general wellbeing
Does the use of scented nose plugs increase the effect of olfactory training on depressive symptoms compared to regular olfactory training? For this outcome, we will use the General Well Being Schedule.
Measured: 2 months
Compliance
Does the use of scented nose plugs increase the compliance of olfactory training compared to regular olfactory training? For this outcome, we will use questions asking the participants about their experience during the olfactory training, specifically targeting their compliance, such as how often they actually completed the olfactory training and how often they forgot to.
Measured: 2 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Nov 2023
- Study start17 Oct 2023
- Primary completion21 Jun 2024
- Study completion1 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for HyposmiaStudies of the same condition, open and under way.
- More trials run by Karolinska InstitutetThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 120 participants (actual)
Sponsor and investigators
- Lead sponsor
- Karolinska Institutet
- Sponsor type
- University, hospital or other
- Collaborators
- Region Skane
- Responsible party
- Principal investigator, Johan Lundström, Karolinska Institutet
- Investigators
- Johan N Lundstrom, Principal investigator, Karolinska Institutet
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06142565
- Sponsor's protocol ID
- 2023-03779-01
- Other IDs
- 2021-06527, 2023
- Status last verified
- Aug 2025
- First submitted
- 8 Nov 2023
- Last updated
- 3 Sep 2025
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Winter AL, Henecke S, Thunell E, Swartz M, Martinsen J, Sahlstrand Johnson P, Lundstrom JN. Olfactory training using nasal inserts is more effective due to increased adherence. Rhinology. 2025 Aug 1;63(4):477-485. doi: 10.4193/Rhin24.369.
PubMed 40278843
Study at a glance
From the registry record, last updated by the sponsor on 3 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Treatment of Postviral Olfactory Dysfunction
- ClinicalTrials.gov ID
- NCT06142565
- Acronym / sponsor ID
- 2023-03779-01
- Conditions
- Hyposmia
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 120 participants (actual)
- Lead sponsor
- Karolinska InstitutetUniversity, hospital or other
- Collaborators
- Region Skane
- Study start
- 17 Oct 2023 (actual)
- Primary completion
- 21 Jun 2024 (actual)
- Study completion
- 1 Jul 2025 (actual)
- First posted
- 21 Nov 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
A decreased sense of smell (hyposmia) is often caused by viral infections, such as COVID-19. Today, the only recommended treatment for hyposmia is olfactory training, a time consuming method with limitations in terms of both compliance and effect. The aim of this study is therefore to evaluate, as well as optimize, a new treatment method for olfactory loss.
Hyposmic participants will be recruited and randomized into two different treatment conditions. One group will do regular olfactory training and the other will do passive olfactory training with scented nose plugs. The training will be conducted in the home of the individual monday through friday for two consecutive months. Subjective and objectvie measures of olfactory problems will be assessed before and after treatment, as well as subjective measures related to quality of live and genereal wellbeing.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Olfactory training with nose plugs | Experimental | Device: Nose plugParticipants will complete olfactory training with scented nose plugs. |
| Olfactory training with household odors | Active comparator | Other: Regular olfactory trainingParticipants will complete olfactory training with odors found in their household. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- 18 - 65 years old
- Physically and cognitively capable of participating in the study
- Having appropriate olfactory screening test scores (hyposmic)
Key exclusion criteria (2 listed)
- Anosmics
- Individuals with other diagnoses that could affect the study results
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Nose plugParticipants will complete olfactory training with scented nose plugs. | Device | Olfactory training with nose plugs |
| Regular olfactory trainingParticipants will complete olfactory training with regular odors found in their home. | Other | Olfactory training with household odors |
Primary outcome
Objective olfactory function
Time frame: 2 months
Does the use of scented nose plugs increase the effect of olfactory training on objective olfactory function compared to regular olfactory training? For this outcome, we will use the standardized Sniffin' Sticks test to assess olfactory function.
Subjective symptoms and social/emotional consequences
Time frame: 2 months
Does the use of scented nose plugs increase the effect of olfactory training on subjective symptoms and social/emotional consequences compared to regular olfactory training? For this outcome, we will use the Sino-Nasal Outcome Test (SNOT).
Subjective health
Time frame: 2 months
Does the use of scented nose plugs increase the effect of olfactory training on subjective health compared to regular olfactory training? For this outcome, we will use the Self-Rated Health 5 measure and SF-36.
Subjective olfactory function
Time frame: 2 months
Does the use of scented nose plugs increase the effect of olfactory training on subjective olfactory function compared to regular olfactory training? For this outcome, we will use the Self-Reported Mini Olfactory Questionnaire.
Subjective degree of suffering from olfactory impairment
Time frame: 2 months
Does the use of scented nose plugs increase the effect of olfactory training on subjective degree of suffering from olfactory impairment compared to regular olfactory training? For this outcome, we will use the Questionnaire of Olfactory Disorders - Negative Statements.
Subjective parosmia
Time frame: 2 months
Does the use of scented nose plugs increase the effect of olfactory training on subjective parosmia compared to regular olfactory training? For this outcome, we will use the Landis parosmia questionnaire.
Subjective depressive symptoms
Time frame: 2 months
Does the use of scented nose plugs increase the effect of olfactory training on depressive symptoms compared to regular olfactory training? For this outcome, we will use the Beck Depression Inventory (BDI).
Subjective general wellbeing
Time frame: 2 months
Does the use of scented nose plugs increase the effect of olfactory training on depressive symptoms compared to regular olfactory training? For this outcome, we will use the General Well Being Schedule.
Compliance
Time frame: 2 months
Does the use of scented nose plugs increase the compliance of olfactory training compared to regular olfactory training? For this outcome, we will use questions asking the participants about their experience during the olfactory training, specifically targeting their compliance, such as how often they actually completed the olfactory training and how often they forgot to.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Sep 2025.
- Results publication: PubMed 40278843Winter AL, Henecke S, Thunell E, Swartz M, Martinsen J, Sahlstrand Johnson P, Lundstrom JN. Olfactory training using nasal inserts is more effective due to increased adherence. Rhinology. 2025 Aug 1;63(4):477-485. doi: 10.4193/Rhin24.369.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Johan N Lundstrom principal investigator
Karolinska Institutet
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Nose plug and Regular olfactory training in people with Hyposmia, run by Karolinska Institutet at 1 site in Sweden.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 3 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Sweden. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Objective olfactory function (time frame: 2 months). The study lists 9 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06142565, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Sep 2025.