Gentian Violet is an antiseptic dye that can be used to treat a variety of fungal infections including athlete's foot and thrush. It also has weak antibacterial effects and may be used on minor cuts and scrapes to prevent infection. It is commonly used in school labs as the basis of the gram stain for detecting the presence of Gram-positive bacteria.
Gentian Violet is also the recommended treatment of mouth ulcers by the World Health Organization. (WHO)