Boric Acid

What does it do? Boric acid is a chemical substance with mild antiseptic properties.1 Boric acid is commonly used in the form of suppositories inserted in the vagina to treat yeast infection. In one study of 100 women with chronic yeast vaginitis that had failed to respond to treatment with over-the-counter or prescription antifungal medicines, 98% of the women successfully treated their infections with boric acid capsules inserted into the vagina twice per day for two to four weeks.2 Several commercial douching products contain boric acid.

The antiseptic activity of boric acid is also used in commercial “artificial tears” and eyewash products.

Boric acid also has antiviral activity. Topical application of diluted boric acid, in the form of sodium borate ointment, has been found to shorten the duration of cold sores in a double-blind trial.3 The duration of cold sores was approximately four days in the group receiving boric acid, compared with six days in the placebo group.

Where is it found? Boric acid is a white, odorless powder or crystalline substance that is available in many over-the-counter pharmaceutical products for topical use, alone as a topical antiseptic, and in suppository form.

Boric acid has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
2Stars Yeast infection
1Star Cold sores
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? Boric acid is not taken internally and is not a nutrient; no deficiency exists.

How much is usually taken? Boric acid is available in powder form from a pharmacy, without a prescription. This powder can be packed into an empty gelatin capsule and used as a suppository. For women with vaginitis, some doctors recommend that one such capsule, containing 600 mg of boric acid, be inserted into the vagina each night for two weeks. Some health food stores have suppositories that contain a combination of boric acid and herbs.

In the trial studying cold sores, an ointment diluted to 4% boric acid was applied four times per day. Because of the potential toxicity of such a preparation, people should consult their doctors before using boric acid.

Are there any side effects or interactions? Boric acid suppositories should not be used during pregnancy. Boric acid is very toxic when taken internally and should also never be used on open wounds. When boric acid enters the body, it can cause nausea, vomiting, diarrhea, dermatitis, kidney damage, acute failure of the circulatory system, and even death. In the past, boric acid was used as a topical treatment for infants with diaper rash. However, even in diluted (3%) form it caused significant toxicity and two deaths.4 Therefore, boric acid should not be applied to the skin of infants and small children. In fact, experts in the field have stated, “The minor therapeutic value of this compound, in comparison with its potential as a poison, has led to the general recommendation that it no longer be used as a therapeutic agent.”5 However, in more recent research, no serious side effects were reported when boric acid was used as a treatment for vaginitis.

At the time of writing, there were no well-known drug interactions with boric acid.

References:

1. van Slyke RK, Michel VP, Rein MF. Treatment of vulvovaginal candidiasis with boric acid powder. Am J Obstet Gynecol 1981;141:145.

2. Jovanovic R, Congema E, Nguyen HT. Antifungal agents vs. boric acid for treating chronic mycotic vulvovaginitis. J Reprod Med 1977;36:593–7.

3. Skinner GRB, Hartley CE, Millar D, Bishop E. Possible treatment for cold sores. BMJ 1979;2:704.

4. Penna RP, Corrigan LL, Welsh J, et al. Handbook of Nonprescription Drugs, 6th ed. Washington, DC: American Pharmaceutical Association, 1979, 424 [review].

5. Penna RP, Corrigan LL, Welsh J, et al. Handbook of Nonprescription Drugs, 6th ed. Washington, DC: American Pharmaceutical Association, 1979, 424 [review].