Oral thrush or oral candidiasis (infection by and accumulation of yeasts, particularly Candida albicans, on the lining of your mouth) is a common condition, especially among people with a compromised immune system. A recent laboratory study confirmed that lemongrass essential oil kills yeasts associated with oral thrush and also improves the activity of nystatin against these yeasts.
https://pubmed.ncbi.nlm.nih.gov/35195155/

Add one drop of lemongrass to your mouthwash to cleanse the oral cavity.