Deficiency of Zinc and Olfactory Dysfunction (Hyposmia) in Post-COVID-19 Patients: A Narrative Review

Abstract

Olfactory dysfunction is one of the most common and specific symptoms of COVID-19, persisting in a significant proportion of patients as part of post-acute sequelae of SARS-CoV-2 infection (PASC). Zinc, an essential micronutrient, has been implicated in immune modulation, neuroregeneration, and olfactory function. Deficiency in zinc may contribute to the persistence of hyposmia after COVID-19. This review aims to evaluate the role of zinc deficiency in post-COVID-19 olfactory dysfunction and to explore the evidence for zinc supplementation as a therapeutic option. A narrative review was conducted by synthesizing data from PubMed, Scopus, and Google Scholar databases (2019–2025). Keywords included “COVID-19,” “post-COVID,” “olfactory dysfunction,” “hyposmia,” and “zinc.” Relevant observational studies, clinical trials, and reviews were included. Multiple studies reported that low serum zinc levels were associated with anosmia and hypogeusia in COVID-19 patients. Molecular evidence suggests dysregulation of zinc transporters in the olfactory mucosa contributes to persistent dysfunction. Clinical trials suggest that zinc supplementation, either alone or in combination with corticosteroids, may accelerate the recovery of smell function in post-COVID patients. However, findings are inconsistent, and optimal dosing remains unclear. Zinc deficiency is likely a contributing factor to post-COVID olfactory dysfunction. Zinc supplementation shows promise as an adjunctive therapy; however, further randomized controlled trials are necessary to establish its efficacy, optimal dosing, and treatment duration.