Objective: Olfactory disorders are associated with poor sexual and mental wellbeing, but prior work mainly consists of retrospective and cross-sectional reports. The current study assessed their prospective associations. Methods: 73 patients with COVID-19-associated olfactory dysfunction were recruited between 2021 and 2023 at a Smell Clinic in Dresden, Germany. Patients were assessed twice, about 6 months apart. On each occasion, patients' olfactory functioning (i.e., psychophysical tests and self-rated function) and sexual and mental wellbeing were measured (i.e., sexual frequency, sexual desire, wellbeing, anxiety symptoms, and depressive symptoms). Results: Within-person improvements in psychophysical olfactory functioning were associated with increased sexual frequency. In a subset of 51 people in stable romantic partnerships, improved psychophysical olfactory functioning predicted increased sexual frequency and increased sexual desire. No evidence emerged supporting an association between improvements in olfactory functioning and mental health or wellbeing outcomes Conclusions: A decline in sexual function may be an early reaction to olfactory dysfunction. Individuals with recent onset of olfactory disorders may benefit from sexual health support.