Boric acid is a very effective treatment and prevention for yeast infections. It helps in promoting the proper acid balance in the vagina. The medication is used for treating yeast infections of the vagina and helps in relieving symptoms such as itching and burning. Boric acid can treat infections that are resistant to first-line treatment. If these don’t work, a doctor may recommend the use of boric acid or another treatment, such as nystatin or flu cytosine.