BackgroundThe global attention to the capacities of traditional medicine for alleviating the clinical manifestations of COVID-19 has been growing. The present trial aimed to evaluate the efficacy and safety of a Persian herbal medicine formula among patients with COVID-19. MethodsThe present trial was conducted in Afzalipour hospital, Kerman, Iran, from June to September 2020. Hospitalized COVID-19 patients were randomly divided into intervention (Persian herbal medicine formula + routine treatment) or control (only routine treatment) groups. The intervention group received both capsule number 1 and 2 every 8 hours for 7 days. Capsule number 1 contained extract of the Glycyrrhiza glabra, Punica granatum, and Rheum palmatum, and the second capsule was filled by Nigella sativa powder. Participants were followed up to 7 days. The primary outcome was the number of hospitalization days, while cough, fever, and respiratory rate, days on oxygen (O2) therapy, and mortality rate were considered as the secondary outcomes. ResultsEighty-two patients were enrolled to the study, while 79 cases completed the trial and their data were analyzed (mean age: 59.1 ± 17.1 years). Based on the results, the Persian medicine formula decreased the mean hospitalization days, so that the mean difference of length of hospitalization as primary outcome was 2.95 ± 0.43 days. A significant clinical improvement was observed regarding dyspnea, need for O2) therapy, and respiratory rate in the intervention group. No adverse effects were reported. ConclusionThe present study supported the use of the Persian medicine formula as an adjuvant therapy for hospitalized COVID-19 patients. Study registrationIranian Registry of Clinical Trials (www.irct.ir): IRCT20200330046899N1.