Smell DysfunctionNCT07309341
Effects of Isotretinoin on Smell
A study testing isotretinoin in people with Smell Dysfunction, run by Uşak University at 1 site in Turkey (Türkiye).
Trial summary
Isotretinoin is a common medicine used to treat moderate to severe acne. It often causes dryness of the skin and the inside of the nose. Because a normal sense of smell depends on a healthy nasal lining, this dryness may affect how well a person can smell. Read more about this study
- Who is it for?
- Ages 18 to 45 years
- Conditions the study is for
- Smell Dysfunction
- What is being tested?
- isotretinoin
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 54 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Jun 2025to 8 Jul 2026
- 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 45 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Diagnosed with acne and scheduled to start oral isotretinoin as part of routine dermatology care
- Willing to participate and able to give informed consent
- Not currently smoking
- No history of allergic rhinitis, sinusitis, or active upper respiratory infection
- No medical condition known to affect the sense of smell
Who cannot join
- Younger than 18 years or older than 45 years
- Current cigarette smoking
- History of chronic sinonasal disease
- Any condition that would prevent completing the smell test
- Not willing to continue participation or withdrawal of consent at any time
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Uşak University Faculty of Medicine
Uşak, Merkez, 64300
About this study
Official title: Effects of Isotretinoin on Nasal Mucociliary Clearance and Olfactory Function
Isotretinoin is a common medicine used to treat moderate to severe acne. It often causes dryness of the skin and the inside of the nose. Because a normal sense of smell depends on a healthy nasal lining, this dryness may affect how well a person can smell.
This study will examine whether isotretinoin treatment changes the sense of smell in adults with acne. Before starting isotretinoin, participants will complete a standardized smell test and two short questionnaires about nasal symptoms and quality of life: the Nasal Obstruction Symptom Evaluation (NOSE) scale and the 22-item Sino-Nasal Outcome Test (SNOT-22). After at least 4 weeks of treatment, the same smell test and questionnaires will be repeated.
By comparing results before and after treatment, the study will test the hypothesis that isotretinoin has a negative effect on olfactory function and may reduce patients' ability to smell.
Read the detailed description
Isotretinoin is a systemic retinoid widely used for the treatment of moderate to severe acne that does not respond adequately to conventional topical or oral therapies. Although highly effective, isotretinoin is known to cause mucocutaneous dryness, which may alter the nasal environment and potentially influence olfactory function. The sense of smell depends on the integrity of the olfactory epithelium, the moisture of the nasal mucosa, and the ability of odorant molecules to reach and dissolve within the mucus layer. Changes in these factors may lead to measurable reductions in olfactory sensitivity or identification ability.
Previous studies examining the effects of isotretinoin on olfaction have produced conflicting results. One investigation reported an increase in olfactory sensitivity during treatment, while another found a decrease in smell function using a different testing method. These inconsistent findings, combined with the limited number of available studies, highlight the need for further research using standardized and reproducible assessment tools.
This prospective clinical study will evaluate olfactory function in adults initiating isotretinoin therapy for dermatologic indications. Participants will undergo a structured olfactory assessment using the Connecticut Chemosensory Clinical Research Center (CCCRC) smell test, which includes both odor identification and discrimination components. In parallel, patient-reported nasal symptoms and sinonasal-related quality of life will be assessed using the NOSE and SNOT-22 questionnaires, allowing a broader understanding of subjective nasal changes that may accompany isotretinoin use.
All assessments will be performed at two time points: before the start of isotretinoin therapy and after a minimum of four weeks of continuous treatment. This within-subject design will allow comparison of pre-treatment and post-treatment measurements to determine whether isotretinoin produces quantifiable changes in olfactory performance. The study hypothesis is that isotretinoin may negatively affect olfactory function due to its well-recognized drying effects on the nasal mucosa.
The findings of this research may assist clinicians in counseling patients regarding potential sensory side effects of isotretinoin and may provide a basis for further investigations into the mechanisms by which systemic medications influence nasal physiology and smell perception.
- Conditions
- Smell Dysfunction
- Being tested
- isotretinoin
- Keywords
- olfaction, smell disfunction, isotretinoin
- Medical subject headings
- Olfaction Disorders, Anosmia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
isotretinoinDrug
Oral isotretinoin prescribed as standard-of-care treatment for acne vulgaris. The dosage, formulation, and duration of therapy will follow routine clinical practice and will be determined by the treating dermatologist based on the participant's clinical condition and body weight. Participants will typically receive daily oral isotretinoin for at least four weeks before the post-treatment assessments.
| Study group | Role | What they receive |
|---|---|---|
| Isotretinoin Treatment Group | Experimental | Participants in this arm will receive standard-of-care oral isotretinoin prescribed by the Dermatology Department for the treatment of acne vulgaris. The dosage and duration of isotretinoin therapy will follow routine clinical practice and will be determined by the treating dermatologist. Olfactory function and nasal symptom assessments will be performed before starting isotretinoin and after at least four weeks of treatment. Receives: Drug: isotretinoin |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Olfactory Function Score
Change in olfactory function from baseline to at least 4 weeks after initiation of oral isotretinoin therapy, measured using the Connecticut Chemosensory Clinical Research Center (CCCRC) smell test. The CCCRC test includes odor identification and odor discrimination components, and yields a composite score representing overall olfactory performance.
Measured: Baseline and 4 weeks after starting isotretinoin treatment.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 Dec 2025
- Study start1 Jun 2025
- Primary completion1 Jul 2026
- Study completion8 Jul 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Smell DysfunctionStudies of the same condition, open and under way.
- 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
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 54 participants (actual)
Sponsor and investigators
- Lead sponsor
- Uşak University
- Sponsor type
- University, hospital or other
- Collaborators
- The Scientific and Technological Research Council of Turkey
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07309341
- Sponsor's protocol ID
- ISO51116
- Other IDs
- 1919B012412359
- Status last verified
- Jun 2026
- First submitted
- 15 Dec 2025
- Last updated
- 13 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared because institutional policy does not permit external sharing of health-related data.
Study at a glance
From the registry record, last updated by the sponsor on 13 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Isotretinoin on Nasal Mucociliary Clearance and Olfactory Function
- ClinicalTrials.gov ID
- NCT07309341
- Acronym / sponsor ID
- ISO51116
- Conditions
- Smell Dysfunction
- Keywords
- olfaction, smell disfunction, isotretinoin
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 54 participants (actual)
- Lead sponsor
- Uşak UniversityUniversity, hospital or other
- Collaborators
- The Scientific and Technological Research Council of Turkey
- Study start
- 1 Jun 2025 (actual)
- Primary completion
- 1 Jul 2026 (actual)
- Study completion
- 8 Jul 2026 (actual)
- First posted
- 30 Dec 2025 (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.
Isotretinoin is a common medicine used to treat moderate to severe acne. It often causes dryness of the skin and the inside of the nose. Because a normal sense of smell depends on a healthy nasal lining, this dryness may affect how well a person can smell.
This study will examine whether isotretinoin treatment changes the sense of smell in adults with acne. Before starting isotretinoin, participants will complete a standardized smell test and two short questionnaires about nasal symptoms and quality of life: the Nasal Obstruction Symptom Evaluation (NOSE) scale and the 22-item Sino-Nasal Outcome Test (SNOT-22). After at least 4 weeks of treatment, the same smell test and questionnaires will be repeated.
By comparing results before and after treatment, the study will test the hypothesis that isotretinoin has a negative effect on olfactory function and may reduce patients' ability to smell.
Detailed description
Isotretinoin is a systemic retinoid widely used for the treatment of moderate to severe acne that does not respond adequately to conventional topical or oral therapies. Although highly effective, isotretinoin is known to cause mucocutaneous dryness, which may alter the nasal environment and potentially influence olfactory function. The sense of smell depends on the integrity of the olfactory epithelium, the moisture of the nasal mucosa, and the ability of odorant molecules to reach and dissolve within the mucus layer. Changes in these factors may lead to measurable reductions in olfactory sensitivity or identification ability.
Previous studies examining the effects of isotretinoin on olfaction have produced conflicting results. One investigation reported an increase in olfactory sensitivity during treatment, while another found a decrease in smell function using a different testing method. These inconsistent findings, combined with the limited number of available studies, highlight the need for further research using standardized and reproducible assessment tools.
This prospective clinical study will evaluate olfactory function in adults initiating isotretinoin therapy for dermatologic indications. Participants will undergo a structured olfactory assessment using the Connecticut Chemosensory Clinical Research Center (CCCRC) smell test, which includes both odor identification and discrimination components. In parallel, patient-reported nasal symptoms and sinonasal-related quality of life will be assessed using the NOSE and SNOT-22 questionnaires, allowing a broader understanding of subjective nasal changes that may accompany isotretinoin use.
All assessments will be performed at two time points: before the start of isotretinoin therapy and after a minimum of four weeks of continuous treatment. This within-subject design will allow comparison of pre-treatment and post-treatment measurements to determine whether isotretinoin produces quantifiable changes in olfactory performance. The study hypothesis is that isotretinoin may negatively affect olfactory function due to its well-recognized drying effects on the nasal mucosa.
The findings of this research may assist clinicians in counseling patients regarding potential sensory side effects of isotretinoin and may provide a basis for further investigations into the mechanisms by which systemic medications influence nasal physiology and smell perception.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Isotretinoin Treatment Group | Experimental | Drug: isotretinoinParticipants in this arm will receive standard-of-care oral isotretinoin prescribed by the Dermatology Department for the treatment of acne vulgaris. The dosage and duration of isotretinoin therapy will follow routine clinical practice and will be determined by the treating dermatologist. Olfactory function and nasal symptom assessments will be performed before starting isotretinoin and after at least four weeks of treatment. |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Diagnosed with acne and scheduled to start oral isotretinoin as part of routine dermatology care
- Willing to participate and able to give informed consent
- Not currently smoking
- No history of allergic rhinitis, sinusitis, or active upper respiratory infection
- No medical condition known to affect the sense of smell
Key exclusion criteria (5 listed)
- Younger than 18 years or older than 45 years
- Current cigarette smoking
- History of chronic sinonasal disease
- Any condition that would prevent completing the smell test
- Not willing to continue participation or withdrawal of consent at any time
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 |
|---|---|---|
| isotretinoinOral isotretinoin prescribed as standard-of-care treatment for acne vulgaris. The dosage, formulation, and duration of therapy will follow routine clinical practice and will be determined by the treating dermatologist based on the participant's clinical condition and body weight. Participants will typically receive daily oral isotretinoin for at least four weeks before the post-treatment assessments. | Drug | Isotretinoin Treatment Group |
Primary outcome
Change in Olfactory Function Score
Time frame: Baseline and 4 weeks after starting isotretinoin treatment.
Change in olfactory function from baseline to at least 4 weeks after initiation of oral isotretinoin therapy, measured using the Connecticut Chemosensory Clinical Research Center (CCCRC) smell test. The CCCRC test includes odor identification and odor discrimination components, and yields a composite score representing overall olfactory performance.
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 13 Jul 2026.
- Individual participant dataSharing planned: No. Individual participant data will not be shared because institutional policy does not permit external sharing of health-related data.
Related trials for Smell Dysfunction
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Impact of Smell Testing on Health Outcomes
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Topical Versus Injection PRP for Olfactory Dysfunction
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Acupuncture for Post-traumatic Olfactory Dysfunction: A Randomized Controlled Trial
Post-traumatic Olfactory Dysfunction, Traumatic Brain Injury
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing isotretinoin in people with Smell Dysfunction, run by Uşak University at 1 site in Turkey (Türkiye).
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 5 inclusion and 5 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 13 Jul 2026. 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 Turkey (Türkiye). 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?
Change in Olfactory Function Score (time frame: Baseline and 4 weeks after starting isotretinoin treatment.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 13 Jul 2026.