There are three main causes of vaginal infections: the fungus (yeast) Candida albicans, the parasite Trichomonas vaginalis, and the bacterial organism Gardnerella vaginalis.

Factors that can contribute to vaginal infections include antibiotics (which kill friendly bacteria, allowing yeast to grow), corticosteroids and HIV (which suppress the immune system), oral contraceptives and pregnancy (which alter the vaginal environment by changing hormone levels), and diabetes (increased sugar levels provide a friendly environment for yeast).

Conventional medical treatment for vaginal infections caused by candida include vaginal suppositories containing antifungal medications or, in some cases, oral antifungal medications. Women with diabetes often find that yeast infections are less common when their blood sugar levels are well controlled.

Trichomonas infections are treated with oral metronidazole, and gardnerella infections with oral or vaginal metronidazole or vaginal clindamycin. So-called nonspecific vaginitis is usually caused by gardnerella, but there are other causes.

Proposed Natural Treatments

There are some promising natural treatments for vaginal infections caused by candida and other organisms, but the scientific evidence for them is not yet strong.

Probiotics (friendly bacteria), such as acidophilus, are normally found in the vagina. When colonies of these organisms are present, it is difficult for unfriendly organisms, such as candida, to become established. Probiotic supplements can help restore a normal balance of vaginal organisms, which could, in theory, reduce the chance of developing a vaginal yeast infection.24 For this reason, women who frequently experience yeast infections, or who are taking antibiotics, are often advised to consume probiotics. However, evidence that probiotics really help prevent vaginal yeast infections remains incomplete and inconsistent.25-26 A fairly large study (278 participants) failed to find Lactobacillus helpful for preventing yeast infections caused by antibiotics.26 Another kind of vaginal infection, called bacterial vaginosis, is most often caused by Gardnerella vaginalis. In a study120 women with a history of bacterial vaginosis, researchers found that vaginally inserting a daily capsule containing the probiotics Lactobacillus rhamnosus, acidophilus, and Streptococcus thermophilus did reduce recurrence.33 While this study found benefit, other studies have produced mixed results regarding the benefits of probiotics in the treatment and prevention of bacterial vaginosis.29-32

Tea tree oil, an essential oil from the plant Melaleuca alternifolia , possesses antibacterial and antifungal properties 7 and appears to spare friendly bacteria in the Lactobacillus family.8 Tea tree oil has been tried for various forms of vaginal infection, but again there is little scientific evidence as yet that it works. In an open trial, 96 women with trichomonal vaginitis were treated with tampons saturated in tea tree oil, which were left in the vagina for 24 hours, and then followed by daily vaginal douches with a tea tree oil solution.9 The researcher reported good results with this regimen in 3 to 4 weeks. However, because this was not a double-blind trial, the results mean little. (For information on why double-blind studies are so important, see Why Does This Database Rely on Double-blind Studies?)

A double-blind study of 100 women found vitamin C vaginal tablets (250 mg) at most marginally helpful for nonspecific vaginitis.28

Boric acid is a chemical substance with antiseptic properties. A double-blind comparison study of 108 women with yeast infections found that 92% of those who used boric acid suppositories nightly for 2 weeks experienced full recovery, as compared to 64% of those given suppositories of the somewhat outdated antifungal drug nystatin.11 However, there are safety concerns with boric acid. If taken internally, it is quite toxic. For this reason, it should not be applied to open wounds. In addition, it should not be used by pregnant women, nor be applied to the skin of infants.13

A single-blind trial, involving 100 women with candida vaginitis, compared nystatin suppositories against suppositories made from the plant Solanum nigrescens and found equivalent benefits.14 However, this plant can be toxic and should not be used except under physician supervision.

Test tube studies have found antifungal properties in numerous herbs, including the tropical tree Tabebuia avellanedae,16 garlic extracts,17-19 the plant alkaloid berberine sulfate (found in goldenseal),20 and essential oils of various plants, including cinnamon, eucalyptus, lemongrass, oregano, palmarosa, and peppermint.21-23 However, it is a long way from test tube studies to proof of safety and effectiveness in people.