NCT06142565

Brief 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. 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.

Trial Health

87
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
120

participants targeted

Target at P50-P75 for not_applicable

Timeline
Completed

Started Oct 2023

Geographic Reach
1 country

1 active site

Status
completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

Study Start

First participant enrolled

October 17, 2023

Completed
22 days until next milestone

First Submitted

Initial submission to the registry

November 8, 2023

Completed
13 days until next milestone

First Posted

Study publicly available on registry

November 21, 2023

Completed
7 months until next milestone

Primary Completion

Last participant's last visit for primary outcome

June 21, 2024

Completed
1 year until next milestone

Study Completion

Last participant's last visit for all outcomes

July 1, 2025

Completed
Last Updated

September 3, 2025

Status Verified

August 1, 2025

Enrollment Period

8 months

First QC Date

November 8, 2023

Last Update Submit

August 26, 2025

Conditions

Hyposmia

Outcome Measures

Primary Outcomes (9)

  • 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.

    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).

    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.

    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.

    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.

    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.

    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).

    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.

    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.

    2 months

Study Arms (2)

Olfactory training with nose plugs

EXPERIMENTAL

Participants will complete olfactory training with scented nose plugs.

Device: Nose plug

Olfactory training with household odors

ACTIVE COMPARATOR

Participants will complete olfactory training with odors found in their household.

Other: Regular olfactory training

Interventions

Nose plugDEVICE

Participants will complete olfactory training with scented nose plugs.

Olfactory training with nose plugs
Regular olfactory trainingOTHER

Participants will complete olfactory training with regular odors found in their home.

Olfactory training with household odors

Eligibility Criteria

Age18 Years - 65 Years
Sexall
Healthy VolunteersNo
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • years old
  • Physically and cognitively capable of participating in the study
  • Having appropriate olfactory screening test scores (hyposmic)

You may not qualify if:

  • Anosmics
  • Individuals with other diagnoses that could affect the study results

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Karolinska Institutet

Solna, Stockholm County, 17177, Sweden

Location

Related Publications (1)

  • 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.

    PMID: 40278843BACKGROUND

MeSH Terms

Conditions

Anosmia

Condition Hierarchy (Ancestors)

Olfaction DisordersSensation DisordersNeurologic ManifestationsNervous System DiseasesSigns and SymptomsPathological Conditions, Signs and Symptoms

Study Officials

  • Johan N Lundstrom

    Karolinska Institutet

    PRINCIPAL INVESTIGATOR

Study Design

Study Type
interventional
Phase
not applicable
Allocation
RANDOMIZED
Masking
NONE
Purpose
TREATMENT
Intervention Model
PARALLEL
Sponsor Type
OTHER
Responsible Party
PRINCIPAL INVESTIGATOR
PI Title
Professor

Study Record Dates

First Submitted

November 8, 2023

First Posted

November 21, 2023

Study Start

October 17, 2023

Primary Completion

June 21, 2024

Study Completion

July 1, 2025

Last Updated

September 3, 2025

Record last verified: 2025-08

Data Sharing

IPD Sharing
Will not share

Locations

SE(1)