Abstract Objectives Since maintaining oral hygiene is essential in nursing care, the present study was conducted to determine the effect of oral care using Mucosamin artificial saliva spray to control dry mouth in ICU patients with COVID-19. Materials and methods The current semi-experimental research was conducted on eighty patients with COVID-19 selected using the available sampling method. The study tool was a Beck oral assessment scale (BOAS). The case and control groups were selected from two hospitals with relatively similar conditions and treatment procedures. For patients in the intervention group, mucosamin artificial saliva spray was used in addition to the common care, while control group patients received only common care. Results Eighty patients were randomly assigned to two groups named control and intervention (40 patients in each group). The intervention was very effective in reducing the BOAS score after four days in comparison with the control group (9.23 vs. 12.05, respectively; p-value