Introduction: Olfactory changes associated with COVID-19 have emerged as one of the most common neurosensory manifestations of SARS-CoV-2 infection. Although many patients experience spontaneous recovery, a significant proportion develops persistent olfactory dysfunction, impacting quality of life, nutrition, environmental safety, and mental health. Objective: To analyze the most recent scientific evidence regarding diagnosis, prognosis, and therapeutic strategies related to post-COVID-19 olfactory changes.  Methods: A systematic literature review was conducted following the PRISMA 2020 guidelines. Searches were performed in the PubMed/MEDLINE, Scopus, Web of Science, Embase, and Cochrane Library databases, including studies published between January 2021 and June 2026. After applying eligibility criteria and removing duplicates, 60 studies were selected for qualitative synthesis.  Results: The studies demonstrated that the pathophysiology of post-COVID olfactory dysfunction involves inflammatory changes in the olfactory epithelium and possible central impairments of olfactory-related neural pathways. Objective diagnostic methods, such as UPSIT and Sniffin’ Sticks, proved essential for the proper assessment of olfactory function. Among the prognostic factors associated with symptom persistence, advanced age, greater initial severity of olfactory loss, and the presence of parosmia stood out. Olfactory training presented the highest level of scientific evidence and is considered the primary therapeutic strategy. Pharmacological therapies and emerging approaches, such as palmitoylethanolamide combined with luteolin and platelet-rich plasma, have shown promising results but still require further validation.  Conclusion: Post-COVID-19 olfactory changes remain a significant clinical challenge, requiring early diagnosis, multidisciplinary follow-up, and therapeutic strategies grounded in scientific evidence.