Acidophilus: Lactobacillus acidophilus ( L. acidophilus ) is the most commonly used probiotic, or "friendly" bacteria. Such healthy bacteria inhabit the intestines and vagina and protect against the entrance and proliferation of "bad" organisms that can cause disease

Lactobacilli are bacteria that normally live in the human small intestine and vagina. Lactobacillus acidophilus is generally considered to be beneficial because it produces vitamin K, lactase, and anti-microbial substances such as acidolin, acidolphilin, lactocidin, and bacteriocin. Multiple human trials report benefits of L. acidophilus for bacterial vaginosis. Other medicinal uses of L. acidophilus are not sufficiently studied to form clear conclusions.

The term "probiotic" is used to describe organisms that are used medicinally, including bacteria such as L. acidophilus and yeast such as Saccharomyces boulardii.

Multiple human studies report that Lactobacillus acidophilus vaginal suppositories are effective in the treatment of bacterial vaginosis. A small number of studies suggest that eating yogurt enriched with Lactobacillus acidophilus may be similarly beneficial. Additional research is necessary before a firm conclusion can be reached