There is no one-size-fits-all answer to this question, as the cause of yeast infections on skin folds will vary depending on the individual's individual situation and skin type. However, some possible causes of yeast infections on skin folds include: skin irritation from the use of certain medications, such as antibiotics, birth control pills, or over the counter supplements, or from skin conditions such as acne or dry skin. Additionally, some people may experience yeast infections when they are using the wrong type of contraception, such as using a condom when having sex.