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Most women experience at least one vaginal yeast infection, and many deal with recurrent infections. Yeast called Candida albicans accounts for most of these infections, which usually clear quickly with topical antifungal medicine. Boric acid vaginal suppositories are used in limited circumstances to treat vaginal yeast infections caused by other species of Candida that have not cleared with other medications. Although the Centers for Disease Control and Prevention (CDC) notes that boric acid suppositories successfully clear about 70 percent of these unusual infections, they can cause vaginal irritation and are highly toxic if accidentally swallowed.

Possible Side Effects

Most women who use boric acid vaginal suppositories as directed experience few, if any, side effects. Unlike oral medications, little of the boric acid present in a vaginal suppository gets absorbed into the body. Therefore, common side effects that occur with many oral medications -- such as stomach upset or headache -- do not occur with boric acid suppositories. However, localized side effects might occur, including: -- vaginal irritation or redness -- a mild burning sensation -- watery discharge -- a gritty sensation during intercourse

If these symptoms are bothersome, a different treatment may be recommended.

Not First-Choice Treatment

Doctors typically do not recommend boric acid suppositories for a vaginal yeast infection caused by Candida albicans. First-choice treatments recommended by CDC include over-the-counter clotrimazole (Femcare, Gyne-Lotrimin), miconazole (Monistat) and tioconazole (Vagistat). Prescription antifungal topical and oral medications are also available and might be recommended in certain situations. Boric acid suppositories are typically not recommended unless cultures show that the Candida albicans causing the infection is resistant to other treatments, which rarely occurs.

Uses of Boric Acid Vaginal Suppositories

Doctors sometimes recommend boric acid suppositories for persistent or recurring vaginal yeast infections caused by yeast called Candida glabrata, Candida tropicalis or other unusual yeast species. Women with diabetes have an increased risk for vaginal infections caused by these atypical types of yeast. Unlike Candida albicans, which causes most vaginal yeast infections, Candida glabrata responds only about 50 percent of the time to standard topical treatment with commonly used medications, such as clotrimazole, miconazole and tioconazole. When antifungal medicines fail to clear a vaginal yeast infection or the infection quickly recurs, boric acid suppositories might be effective.

Warnings and Precautions

Boric acid vaginal suppositories are generally safe when used as directed, although there is no information about the safety of long-term use. They are relatively inexpensive, though somewhat inconvenient to obtain since they typically need to be compounded by the pharmacist.

Pregnant women should not use boric acid suppositories because of a potential risk to the fetus. Swallowing boric acid capsules can be fatal, so it's important to keep this medication out of the reach of children. If boric acid is swallowed, seek emergency medical attention.

Reviewed and revised by: Tina M. St. John, M.D.