Study	Reason for exclusion
ACTION (NCT04332107)	Wrong population: study does not specifically include participants with olfactory dysfunction
Begam 2020	Narrative review article, no primary data
COPPS (NCT04662060)	Wrong population: study does not specifically include participants with olfactory dysfunction
Co‐STAR (NCT04422275)	Although this study fits the inclusion criteria for the review, it was withdrawn prior to any participant enrolment
COVIDAtoZ (NCT04342728)	Wrong population: study does not specifically include participants with olfactory dysfunction
COVIDORL (NCT04361474)	Wrong population: all participants in the study have had symptoms of olfactory disturbance for at least 4 weeks. This study is relevant for the companion review "Interventions for the treatment of persistent post‐COVID‐19 olfactory dysfunction" (Webster 2021a).
CTRI/2020/08/027477	Wrong population: study does not specifically include participants with olfactory dysfunction
IRCT20200522047542N1	Wrong population: all participants in the study have had symptoms of olfactory disturbance for at least 4 weeks. This study is relevant for the companion review "Interventions for the treatment of persistent post‐COVID‐19 olfactory dysfunction" (Webster 2021a).
NCT04374474	Although this study fits the inclusion criteria for the review, it was withdrawn prior to any participant enrolment
NCT04382547	Wrong study design: not a randomised controlled trial
NCT04406584	Wrong population: includes participants with any post‐viral olfactory disturbance (not specifically COVID‐19)
NCT04414124	Wrong population: study does not specifically include participants with olfactory dysfunction
NCT04427332	Wrong study design: observational study, not a randomised controlled trial
NCT04458519	Wrong population: study does not specifically include participants with olfactory dysfunction
NCT04474483	Wrong population: study does not specifically include participants with olfactory dysfunction
NCT04513184	Wrong population and wrong comparator: study does not specifically include participants with olfactory dysfunction; intervention is compared to intravenous dexamethasone
NCT04622891	Wrong population: study does not specifically include participants with olfactory dysfunction
NCT04662086	Wrong population: study does not specifically include participants with olfactory dysfunction
Odorat‐Covid (NCT04598763)	Wrong population: all participants in the study have had symptoms of olfactory disturbance for at least 4 weeks. This study is relevant for the companion review "Interventions for the treatment of persistent post‐COVID‐19 olfactory dysfunction" (Webster 2021a).
Patel 2021	Letter to the editor: no primary data included
Pinna 2020	Letter to the editor: no primary data included
Vaira 2020	Wrong population: all participants in the study have had symptoms of olfactory disturbance for at least 4 weeks. This study is relevant for the companion review "Interventions for the treatment of persistent post‐COVID‐19 olfactory dysfunction" (Webster 2021a).
Vroegop 2020	Narrative review article: no primary data