General Information: Boric acid is available as an ophthalmic solution and a vaginal suppository. The ophthalmic solution is used as an irrigation for irritated eyes and to remove foreign materials from the eyes. The vaginal suppository is used to treat the symptoms of vulvovaginal candidiasis. There is a risk of developing systemic toxicity from the topical application of boric acid preparations especially in infants and children, if the skin is broken, or if large amounts of the drug are applied. Boric acid was first marketed in 1939. In January, 2016, a homeopathic vaginal suppository became commercially available for the treatment of vulvovaginal candidiasis; the product has not been evaluated by the FDA for safety or efficacy for the stated use and the FDA is not aware of scientific evidence to support homeopathy as effective.
Mechanism of Action: Boric acid is a weak topical anti-infective agent with fungistatic and bacteriostatic properties. The exact mechanisms of boric acids antibacterial and antifungal actions are unclear. Boric acid exerts slow-acting bacteriostatic activity against staphylococci and streptococci. There is some evidence, specific to vaginal use, suggesting that the fungistatic activity of boric acid is due to vaginal acidification, which results in fungal cell wall penetration and disruption of the fungal cell membrane. Alternatively, other evidence suggests that boric acid works at a pH similar to that of the healthy, untreated vaginal tract, and, therefore, the activity of boric acid may not be a result of increased vaginal acidity.12
Pharmacokinetics: Boric acid is administered as an ocular eyewash solution or intravaginal suppository. Boric acid is not significantly metabolized, and about 50% of the amount absorbed is excreted unchanged in the urine within 24 hours. Nearly total excretion is found in the urine within 96 hours.1
Oral Route: If boric acid is ingested orally, there is virtually complete gastrointestinal absorption. Once absorbed, boric acid is widely distributed throughout body water and accumulates in the brain, liver, and kidneys and can be toxic. Boric acid preparations should never be administered orally.
Topical Route: Boric acid does not readily penetrate intact skin, but is absorbed from damaged skin and mucous membranes.
Intravaginal Route: Following intravaginal administration of boric acid suppositories, there is minimal absorption (6%) from the vagina with a half-life of less than 12 hours.3 The intravaginal administration of boric acid vaginal suppository is expected not to pose risk of systemic toxicity at the prescribed dosage.2
Pediatrics: Boric acid is more readily absorbed when applied topically to infants and children and systemic exposure can be toxic.
For the treatment of vulvovaginal candidiasis†:
Intravaginal dosage (vaginal suppository):
Adult and Adolescent females: The commercially available product is homeopathic and has not been evaluated by the FDA for safety and efficacy. For acute infection, the manufacturer recommended dose is 1 capsule suppository vaginally once daily for 3 days or as prescribed. For chronic infection or related symptoms, insert 1 capsule suppository vaginally once daily for 6 days or as prescribed.2 Per the CDC, the optimal treatment of nonalbicans infection remains unknown. Options include longer duration of therapy (7 to 14 days) with a non-fluconazole azole regimen (oral or topical) as first-line therapy. For recurrence, an option is to use 1 boric acid suppository (600 mg) vaginally once daily for 2 weeks; this regimen has clinical and mycologic eradication rates of approximately 70%.4
For the treatment of recurrent bacterial vaginosis†:
Intravaginal dosage (vaginal suppository):
Adults and Adolescents: The commercially available product is homeopathic and has not been evaluated by the FDA for safety or efficacy in treating vaginal conditions.2 Per the CDC, limited data suggest that an oral nitroimidazole (metronidazole or tinidazole 500 mg twice daily for 7 days) followed by boric acid 600 mg suppository vaginally once daily for 21 days and then suppressive 0.75% metronidazole gel twice weekly for 4 to 6 months might be an option for women with recurrent bacterial vaginosis.4
NOTE: This is a homeopathic product and safety or efficacy have not been evaluated by the FDA.
Vaginal capsule suppository
- For intravaginal use only.
- Patients should be instructed in proper installation of vaginal suppositories.
- Vaginal Administration:
- Wash hands thoroughly with soap and water.
- Take out the capsule suppository from the foil pouch and insert the capsule suppository into the open end of the applicator.
- Gently insert the applicator with the vaginal capsule suppository into the patient's vagina as far as possible, following the directions of the product.
- Depress the plunger so that the capsule suppository is released.
- Withdraw the applicator and discard the disposable applicator.
- Wash hands after insertion.
- Patient may wish to wear a panty liner after product is inserted as directed.2
Contraindications: Do not use boric acid products in patients with a history of an allergic reaction to boric acid or any of the product ingredients; discontinue use of allergic-type reactions occur.2
Boric acid should never be administered to neonates or infants. Do not use boric acid vaginal products in children 12 years or younger.24 Keep all boric acid products out of the reach of children; oral accidental exposure must be avoided in patients of any age. The risk of systemic toxicity from boric acid depends on the concentration used, route of administration, age of the patient, skin condition, and duration of exposure. The fatal adult dose is about 20 grams or 0.1 to 0.5 mg/kg taken orally. Even topical administration of boric acid powder for diaper dermatitis has caused toxic reactions and fatalities in infants. If accidentally swallowed, seek medical help or contact the Poison Control Center immediately.562
Boric acid vaginal suppositories are not recommended for use by patients with high blood pressure, cardiac disease or blood vessel disease. Vaginal use is not recommended in patients with immunosuppression, including patients with acquired immunodeficiency syndrome (AIDS); use is considered contraindicated by the manufacturer.24 Patients with known sexually transmitted disease (STD) or a history of pelvic inflammatory disease (PID) should only receive the vaginal boric acid products under the close supervision and prescription of a healthcare provider.4 Patients should discontinue use and seek medical examination and advice for any vaginal bleeding, sores, ulcerations, nausea, fever or chills, sensitivity in your lower pelvis or abdomen, or suspected sexually transmitted disease (STD) or pelvic inflammatory disease (PID).2 Open genital or vaginal wounds can increase the risk for systemic absorption of boric acid and toxicity.2 Systemic absorption of topical boric acid may also result in severe poisonings and fatalities. Conditions which increase systemic absorption include use over large surface areas, prolonged use, use in areas where the epidermal barrier is disrupted (i.e., skin abrasion), and the use of an occlusive dressing.
Boric acid vaginal products should not be used during human pregnancy due to the risk of teratogenic effects and the lack of data demonstrating safety.2 Topical boric acid preparations should also not be used in pregnant women unless the benefit outweighs the potential risk.
It is not known if boric acid is excreted in breast milk. No data is available regarding the safety of boric acid vaginal products in lactating mothers; therefore, vaginal boric acid should not be recommended in this patient population.2 Topical boric acid products should not be used to soothe irritated skin on the breast or nipple, or to any area of the skin to which the infant could potentially be exposed, in women who are breast-feeding. Boric acid does not readily penetrate intact skin and there is minimal systemic absorption vaginally.3 Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.
Pregnancy: Boric acid vaginal products should not be used during human pregnancy due to the risk of teratogenic effects and the lack of data demonstrating safety.2 Topical boric acid preparations should also not be used in pregnant women unless the benefit outweighs the potential risk.
Breast-feeding: It is not known if boric acid is excreted in breast milk. No data is available regarding the safety of boric acid vaginal products in lactating mothers; therefore, vaginal boric acid should not be recommended in this patient population.2 Topical boric acid products should not be used to soothe irritated skin on the breast or nipple, or to any area of the skin to which the infant could potentially be exposed, in women who are breast-feeding. Boric acid does not readily penetrate intact skin and there is minimal systemic absorption vaginally.3 Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.
Interactions: There are no drug interactions associated with Boric Acid products.
Adverse Reactions: Generally, boric acid vaginal products are not associated with significant adverse effects when used for short courses (6 days or less) for vaginal conditions. Most side effects with vaginal suppository use are considered mild and may include watery vaginal discharge, vaginal irritation, erythema, or a slight burning sensation, or a gritty sensation with intercourse during the treatment period. It is advised to avoid sexual intercourse during the treatment period; patients may also wish to wear a panty liner due to potential vaginal discharge with treatment.2 Allergic reactions can occur with any boric acid product and may include anaphylactoid reactions, dyspnea or difficulty breathing, chest pain (unspecified), angioedema, pruritus, urticaria or other rash (unspecified), pruritus, and skin irritation or inflammation. If these occur, discontinue use.
When boric acid is ingested, applied repeatedly, in higher concentrations, and/or large amounts to wounds, burns, abrasions, denuded, or macerated skin, or when applied to large areas of the skin, severe boric acid poisoning and fatalities have occurred. Systemic toxicity occurs with oral ingestion of boric acid as well. The risk of systemic toxicity depends on the concentration used, route of administration, age of the patient, skin condition, and duration of exposure. The fatal adult dose is about 20 grams or 0.1 to 0.5 mg/kg taken orally. Intravaginal boric acid is safe to use and expected not to pose risk of systemic toxicity at the prescribed dosage.2 There appears to be a higher incidence of toxicity in infants and children under the age of 3 years with topical application. Signs and symptoms of acute toxicity following excessive absorption of boric acid may include: nausea and vomiting; diarrhea; abdominal pain; hemorrhagic gastroenteritis; CNS stimulation (weakness, lethargy, headache, restlessness, tremor, twitching of facial muscles and extremities, and seizures) followed by CNS depression; metabolic acidosis; intravascular coagulation; and fever. Severe and fatal poisoning with boric acid may manifest as oliguria, anuria, renal tubular necrosis, hepatomegaly, jaundice, cyanosis, shock, circulatory collapse, and death. If accidentally swallowed or if systemic toxicity is suspected, seek medical help or contact a poison control center immediately.562
Storage: Store this medication at 68°F to 77°F (20°C to 25°C) and away from heat, moisture and light. Keep all medicine out of the reach of children. Throw away any unused medicine after the beyond use date. Do not flush unused medications or pour down a sink or drain.
- 1. Prutting SM, Cerveny JD. Boric Acid Vaginal Suppositories: A Brief Review. Infect Dis Obstet Gynecol 1998;6:191-4.
- 2. Hylafem (boric acid) vaginal suppository package insert. Decatur, GA: US Pharmaceutical Corp.; 2016 Jan.
- 3. Van Slyke KK, Michel VP, Rein MF. Treatment of vulvovaginal candidiasis with boric acid powder. Am J Obstet Gynecol 1981;141:145-8.
- 4. Centers for Disease Control and Prevention (CDC). Sexually Transmitted Diseases Treatment Guidelines 2015. MMWR. 2015;64(3):1-137
- 5. Baliah T, MacLeish H, Drummond KN. Acute boric acid poisoning: report of an infant successfully treated by peritoneal dialysis. Can Med Assoc J 1969;101:166-8.
- 6. Rosen FS, Haggerty RJ. Fatal poisoning from topical use of boric acid powder. N Engl J Med 1956;255:530-1.