Boric Acid

Boric Acid Chemical formula

💊 Chemical information

Acide borique; Ácido bórico; Acidum boricum; Boorihappo; Boracic Acid; Borato ru _ gštis; Borsäure; Bórsav; Borsyra; E284; Kwas borowy; Kyselina boritá; Orthoboric Acid; Sal Sedativa de Homberg.
Chemical formula: H3BO3 = 61.83.
CAS — 10043-35-3.
ATC — S02AA03.
ATC Vet — QS02AA03.


In Chin., Eur., Jpn, and Viet. Also in USNF.

Ph. Eur. 6.2

(Boric Acid). Colourless shiny plates greasy to the touch, or white or almost white crystals, or white or almost white crystalline powder. Soluble in water and in alcohol; freely soluble in boiling water and in glycerol (85%). A 3.3% solution in water has a pH of 3.8 to 4.8.


(Boric Acid). Odourless, colourless, somewhat pearly lustrous scales, or crystals, or white powder, slightly unctuous to the touch. Soluble 1 in 18 of water, 1 in 4 of boiling water, 1 in 18 of alcohol, 1 in 6 of boiling alcohol, and 1 in 4 of glycerol.


Boric acid volatilises in steam. It forms a complex with glycerol which is a stronger acid than boric acid.

💊 Adverse Effects, Treatment, and Precautions

The main symptoms of acute boric acid poisoning are vomiting and diarrhoea, abdominal pain, an erythematous rash involving both skin and mucous membranes, followed by desquamation, and stimulation or depression of the CNS. There may be convulsions and hyperpyrexia. There may also be renal tubular damage. Abnormal liver function and jaundice have been reported rarely. Death, resulting from circulatory collapse and shock, may occur within several days. The slow excretion of boric acid can lead to cumulative toxicity during repeated use. Symptoms of chronic intoxication include anorexia, gastrointestinal disturbances, debility, confusion, dermatitis, menstrual disorders, anaemia, convulsions, and alopecia. Fatalities have occurred most frequently in young children after the accidental ingestion of solutions of boric acid or after the application of boric acid powder to abraded skin. In the UK the use of boric acid, borates, and tetraborates in cosmetics is controlled: the concentration is limited to 5% in talcs, to 0.1% in products for oral hygiene, and to 3% in other cosmetic products; tetraborates are limited to 18% in bath products. Such cosmetic products should not be used in children under 3 years of age; preparations used for oral hygiene should not be swallowed; and topical preparations containing greater than the equivalent of 1.5% of boric acid should not be applied to peeling or irritated skin. Deaths have resulted from absorption after lavage of body cavities with solutions of boric acid, and this practice is no longer recommended. Inhaled boric acid and borax are pulmonary irritants. Treatment of poisoning is symptomatic. The stomach should be emptied if the patient presents within 1 hour of ingesting a large amount of boric acid; activated charcoal is not effective. Haemodialysis may be of value in severe cases. Pharmacists have also been advised not to supply Borax Glycerin or Honey of Borax, even with an appropriate warning, because of the hazards associated with the use of these preparations in infants.

💊 Pharmacokinetics

Boric acid is absorbed from the gastrointestinal tract, from damaged skin, from wounds, and from mucous membranes. It does not readily penetrate intact skin. About 50% of the amount absorbed is excreted in the urine within 24 hours and most of the remainder is excreted within 96 hours of ingestion.

💊 Uses and Administration

Boric acid possesses weak bacteriostatic and fungistatic properties; it has generally been superseded by more effective and less toxic disinfectants. It is used as a pesticide against ants and cockroaches. Boric acid is used, usually with borax, as a buffer and antimicrobial in eye drops, and was formerly used as a soluble lubricant in solution-tablets. It is also used as a preservative for urine samples. Boric acid and borax are not used internally. In the UK, the use of boric acid in cosmetics and toiletries is restricted (see above). Borax is used similarly to boric acid and has also been used externally as a mild astringent and as an emulsifier in creams. Preparations of borax in glycerol or in honey (Borax Glycerin; Honey of Borax) were formerly used as paints for the throat, tongue, and mouth, but should not be used because of the risk of toxicity. Other salts of boric acid, including potassium and zinc salts, have been used.


Boric acid has been used in homoeopathic medicines under the following names: Acidum boricum; Acidum Boracicum; Ac. boric. Borax has been used in homoeopathic medicines under the following names: Natrium tetraboracicum.

Antimicrobial activity.

Evaluation of the antimicrobial activity of 1.22% borate buffer.1
1. Houlsby RD, et al. Antimicrobial activity of borate-buffered solutions. Antimicrob Agents Chemother 1986; 29: 803–6.

Urine preservation.

Boric acid in concentrations of about 2% may be a suitable preservative for urine samples in transit requiring bacteriological examination.1,2 However, overnight storage of specimens preserved with boric acid may significantly alter culture results.3
1. Porter IA, Brodie J. Boric acid preservation of urine samples. BMJ 1969; 2: 353–5
2. Lum KT, Meers PD. Boric acid converts urine into an effective bacteriostatic transport medium. J Infect 1989; 18: 51–8
3. Gillespie T, et al. The effect of specimen processing delay on borate urine preservation. J Clin Pathol 1999; 52: 95–8.


Vaginal candidiasis caused by Candida glabrata and other non-albicans species frequently responds to topical boric acid.1,2 Satisfactory clinical and mycological responses to topical boric acid were reported in 2 patients with Candida glabrata vaginitis who had not responded to repeated courses of azole antifungals.3 Treatment with boric acid effected clinical and mycological cure in 4 of 6 patients with refractory vaginitis caused by C. krusei.4 Long-term boric acid treatment showed promise in the treatment and prevention of relapses of vulvovaginal candidiasis, but its efficacy ended when treatment was stopped.5
1. Sobel JD, Chaim W. Treatment of Torulopsis glabrata vaginitis: retrospective review of boric acid therapy. Clin Infect Dis 1997; 24: 649–52
2. Pappas PG, et al. Infectious Diseases Society of America. Guidelines for treatment of candidiasis. Clin Infect Dis 2004; 38: 161–89. Also available at: doi/pdf/10.1086/380796 (accessed 24/07/08
3. Redondo-Lopez V, et al. Torulopsis glabrata vaginitis: clinical aspects and susceptibility of antifungal agents. Obstet Gynecol 1990; 76: 651–5
4. Singh S, et al. Vaginitis due to Candida krusei: epidemiology, clinical aspects, and therapy. Clin Infect Dis 2002; 35: 1066–70
5. Guaschino S, et al. Efficacy of maintenance therapy with topical boric acid in comparison with oral itraconazole in the treatment of recurrent vulvovaginal candidiasis. Am J Obstet Gynecol 2001; 184: 598–602.

💊 Preparations

BP 2008: Kaolin Poultice; BPC 1973: Magenta Paint; Surgical Chlorinated Soda Solution; USP 31: Rose Water Ointment.

Proprietary Preparations

Canad.: Eye Wash; Fr.: Dacryum; Hydralin; Optrex; Pol.: Aphtin; Borasol; Gemiderma; Turk.: Bibora; Venez.: Sax. Multi-ingredient: Arg.: Anusol; Baby-Tex; Banoftal†; Bentophyto; Calcusan Bebe; Fungocop; Gineseptina†; Griseoplus; Hipoglos Cicatrizante; Hipoglos con Hidrocortisona; Histidanol†; Hyaluron; Irigal; Lagrimas de Santa Lucia†; Lemil; Parencias†; Perfungol†; Phylarm; Plusderm†; Prurisedan; Sebulex; Austral.: Gold Cross BOZ Ointment†; Austria: Coldophthal; Ophtaguttal; Belg.: Alcasol; Boradrine; Borostyrol; Ocal; Sedemol; SulfaSedemol; Braz.: Adeglos†; Antiphlogistine†; Bluderm†; Cariderm†; Cloraseptic; Colpagex N; Dermosed†; Dinill; Gynax-N; Gyrol†; Higicler; Hipodermon; Lavolho†; Leucocida†; Lucretin; Malvona†; Oto-Biotic†; Oturga; Po Antisseptico; Polvilho Antisseptico†; Pomaderme; Senophile†; Talco Alivio†; Vagitrin-N; Visiplex; Visual†; Canad.: British Army Foot Powder†; Thunas Eye Drops†; Chile: Dexagin; Frescansol; Hipoglos; Homeoplasmina†; Perfungol; Cz.: Aphlox†; Herbadent; Ophtal; Ophthalmo-Septonex; Pityol; Fin.: Otiborin; Fr.: Borostyrol; Dacryoboraline; Dacryoserum; Dacudoses; Eau Precieuse; Homeoplasmine; Hydralin; Ophtaclair; Ophtalmine; Paps; Pate a l’Eau Roche-Posay†; Phylarm†; Sophtal; Ger.: Ensinger SchillerQuelle Heilwasser†; Gr.: Oulogram; Septobore; Vaseline Borique; Hong Kong: Eye Glo Plus; Eye Glo Regular; Eye Wash; Gly Thymol; Hydralin; India: Andre; Feel Chill; New Eye Lotion; Proto-Boric; Indon.: Skintex; Verile; Irl.: Phytex; Israel: Gargol; Ital.: Aquasalina†; Bagno Oculare†; Bergacid; Boma; Fotofil; Fucsina Fenica; Mex.: Clarex; Forcremol; Hipoglos; Lav Ofteno; Lowila; Oftaboril; Tokolirio; Mon.: Boroclarine; Philipp.: Soothing Eye Wash; United Home Burn Ointment; Pol.: Acifungin; Afronis; Dentosept A; Gargarin; Hemorectal; Neo-Tormentil; Pigmentum Castellani; Tormentile Forte; Tormentiol; Rus.: Contraceptin T (Контрацептин Т); Lysoplac (Лизоплак); Osarbon (Осарбон); S.Afr.: Anugesic; Caloplast; Prep; Universal Eye Drops; Vagarsol; Singapore: Eye Mo†; New Daigaku†; Spain: Banoftal; Cloran Hemidex; Coliriocilina Adren Astr; Dermomycose Liquido; Fungusol; Lamnotyl†; Milrosina; Natusan; Oftalmol Ocular; Pomada Infantil Vera†; Topico Denticion Vera†; Vaselina Boricada; Zolina; Swed.: Antasten-Privin; Thai.: Eye Mo; Eye-Gene; Eye-Gene Soft; Mano; Opplin†; Opsil†; Optal; Optic; Quinradon-N; Visotone; Turk.: Antidot; Dermikolin; Undo-Talk; UK: Oxy Clean Facial Scrub; Phytex; USA: BFI; Castaderm; Collyrium for Fresh Eyes; Columbia Antiseptic Powder; Dri/Ear; Ear-Dry; Paladin; Phylorinol; RA Lotion; Saratoga; Seale’s Lotion; Star-Otic; Trimo-San; Venez.: Ademina; Boramint†; Bori-Zinc†; Borocanfor; Borogin; Diodonato†; Hipoglos†; Micofeet; Polifix†; Sebaxyl.
Published January 23, 2019.