Background: Incomplete data are presented to determine the role of vitamin A supplement therapy to improve outcomes in patients with coronavirus disease 2019 (COVID-19). Aims: We compared treatment effects between a groups that received vitamin A added to the standard COVID-19 treatment and a group that received the standard drug treatment alone. Methods: In this triple-blind controlled trial, the participants comprised 182 COVID-19 outpatients in Saveh city, Markazi Province, Islamic Republic of Iran, in 2020. Patients were randomly divided into experimental (n = 91) and control (n = 91) groups. Patients in the control group received the national standard treatment for COVID-19 (hydroxychloroquine), and those in the intervention group received 25 000 IU/d oral vitamin A for 10 days in addition to the standard treatment recommended by the national protocol. We evaluated the clinical symptoms, paraclinical criteria and hospitalization status before and 10 days after both interventions. Results: The treatment groups did not differ significantly in terms of clinical and paraclinical symptoms before the intervention, but clinical symptoms such as fever, body ache, weakness and fatigue, paraclinical symptoms, white blood cell count and C-reactive protein showed a significantly greater decrease in the experimental group 10 days post-intervention compared with the standard treatment alone (P < 0.05). Conclusion: Vitamin A supplement demonstrated efficacy in improving some clinical and paraclinical symptoms in patients with COVID-19. Future studies should evaluate vitamin A supplementation with a larger sample size and compare different dosages, especially in hospitalized patients.