Angular cheilitis (pronounced key-litis), in the simplest terms, is inflammation at the corners of the mouth, causing those areas to look red, swollen, and cracked.
Your mouth is its own ecosystem, containing many species of bacteria, viruses, and fungi, including a type of fungus called Candida albicans. For the most part, a normal amount of Candida albicans lives in your mouth and other places on your body (like your vagina) without causing harm, but sometimes, it can multiply and lead to an infection called candidiasis, according to the Centers for Disease Control and Prevention.
So, how exactly does this lead to angular cheilitis? Good question.