Corticosteroids improve the complications of Covid-19 but may cause some side effects such as hyperglycemia. Royal jelly is one of the bee products that exert anti-inflammatory, insulin-like, and hypoglycemic activities. The present study was conducted to investigate the effect of royal jelly capsules on blood sugar and the clinical course of Covid-19 in the patients receiving corticosteroid therapy. In this clinical trial, 72 Covid-19 patients with positive reverse transcription polymerase chain reaction (RT-PCR) test and pulmonary involvement hospitalized in Shahrekord Hajar Hospital were enrolled and randomized into two groups: treatment (receiving corticosteroids and Royal Jelly 1000 mg capsules daily for 7 days) and placebo (given corticosteroids and placebo). Laboratory tests, blood sugar, and clinical courses were determined and compared. Data was analyzed using SPSS version 16. On day 7 after the onset of the intervention, the dosage and frequency of insulin, FBS level, and required corticosteroid showed a decrease in both groups but the inter-group difference was not significant ( P > .05). As well, the Spo2 level indicated a non-significant increase and hospital stay length indicated a non-significant decrease in the intervention group ( P > .05). Among the symptoms, only headache, cough, and dyspnea indicated an improvement in the intervention group ( P < .05). Overall, the results indicated the short-term consumption of royal jelly could not significantly improve blood sugar and the clinical course of Covid-19; however, it could significantly improve headache, cough, and dyspnea in the patients.