Bacitracin
The ointment in every first-aid kit, with a rare reaction serious enough to be worth knowing about
Bacitracin is a cyclic peptide antibiotic made by Bacillus bacteria. It is sold over the counter for minor cuts and burns, usually combined with neomycin and polymyxin B. It is too damaging to the kidneys to inject, and it causes true anaphylaxis often enough to be documented.
What is it?
Bacitracin blocks bacterial cell-wall building by tying up the lipid carrier that ferries wall units across the membrane, which is a different point of attack from the beta-lactams. It works on gram-positive bacteria; the polymyxin B in combination products covers the gram-negatives.
The label on the triple-antibiotic ointments cached for this entry is unglamorous and precise: first aid to help prevent infection in minor cuts, scrapes and burns, a fingertip-sized amount one to three times a day, ask a doctor under two years of age.
The human evidence is thin for something so widely used, and where it has been compared it has rarely won. Against mupirocin for clearing Staphylococcus aureus from the nose of healthcare workers, bacitracin cleared 44% against mupirocin's 94%. After skin surgery, in 922 patients, it did not significantly reduce infections against plain petrolatum, and only the bacitracin group developed allergic reactions. A bismuth-based wound product healed biopsy wounds faster.
Other routes have been tried and mostly abandoned. Injected, it damaged the kidneys, and injectable bacitracin was recalled; studies of breast implant surgery before and after the recall found irrigating pockets with it made no difference to infection. By mouth it was once part of bowel preparation before colorectal surgery and was tested against C. difficile and VRE, with mixed results. Nebulised with colimycin for chronic sinusitis, it matched placebo.
Its distinctive risk is allergy. Bacitracin is a well-known cause of contact dermatitis, and case reports describe immediate, IgE-mediated anaphylaxis after ointment on broken skin.
Mechanism of Action
Bacitracin is a cyclic peptide antibiotic that stops gram-positive bacteria from recycling the lipid carrier they need to build their cell wall.
Lipid carrier
Binds the carrier lipid that moves cell-wall building blocks across the membrane.
Gram-positive
Active mainly against gram-positive bacteria; combination ointments add polymyxin B and neomycin.
Allergy
A common cause of contact dermatitis, with rare anaphylaxis.
Published Research
These are the studies in people, read from their PubMed abstracts: one comparison, one older oral trial and two reports of anaphylaxis.
Beaten by mupirocin in the nose
In a randomised trial in 34 healthcare workers carrying Staphylococcus aureus in the nose, five days of treatment eradicated the organism in 94% of those given mupirocin and 44% of those given bacitracin (p = 0.0031), with the same pattern at 30 days.
Anaphylaxis from an ointment
A 24-year-old man developed severe anaphylaxis five minutes after bacitracin zinc ointment was applied to extensive abrasions, needing adrenaline, antihistamines, fluids and steroids. Skin testing afterwards was positive to the bacitracin ointment alone.
Not an isolated case
A 1978 case report of anaphylaxis after bacitracin; PubMed carries no abstract, so only the event itself is recorded here.
Taken by mouth, for a parasite
In a randomised trial in giardiasis, ten days of oral bacitracin zinc cleared Giardia from the stool of all 21 patients treated, against 95% on bacitracin, 91% on neomycin and 90% on the combination. Oral bacitracin is not absorbed, which is why it could be used this way.
Oral, for C. difficile diarrhoea
In a double-blind trial, 10 days of oral bacitracin resolved C. difficile diarrhoea as well as vancomycin, but toxin was cleared from stool less often (30% against 71%), and five bacitracin patients against three on vancomycin had a recurrence.
Not for VRE carriage
In 12 patients colonised with vancomycin-resistant Enterococcus faecium, 10 days of oral zinc bacitracin cleared the gut no better than placebo (2 of 6 in each group at 3 weeks).
Against plain petrolatum after skin surgery
In 922 ambulatory skin-surgery patients, wound infection was 0.9% with bacitracin ointment and 2.0% with white petrolatum, not significantly different; S. aureus infections occurred only with petrolatum, and allergic contact dermatitis occurred only with bacitracin.
Wound healing in a biopsy model
In a human forearm biopsy model powered for equivalence, wounds treated with a bismuth subgallate-borneol product healed faster than those treated with bacitracin.
Nebulised for chronic sinusitis
In recalcitrant chronic rhinosinusitis with S. aureus, nebulised bacitracin plus colimycin did no better than placebo on symptoms, quality of life or endoscopy.
Oral, before colorectal surgery
In 149 evaluable patients, oral bacitracin and neomycin with metronidazole and ampicillin prevented infection about as well as single-dose fosfomycin plus metronidazole (10% against 13% infective complications).
Breast implant pockets after the injection recall
After injectable bacitracin was recalled, 254 breast implants irrigated with or without it showed no difference in infection (6.4% against 8.5%) or cellulitis.
Breast reconstruction outcomes
In 188 women having implant-based breast reconstruction, bacitracin irrigation did not protect against infection in univariate or multivariable analysis; age over 50 did predict infection.
What the combination spray covers
A spray combining polymyxin B and bacitracin zinc was tested against 353 clinical isolates, 202 gram-positive and 151 gram-negative, measuring zones of inhibition on agar.
Dosing Data
Bacitracin today is a topical first-aid ointment, applied in a small amount to minor wounds one to three times a day.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
Side Effects & Contraindications
Reported Side Effects
From the over-the-counter label and the case reports above.
Contraindications & Cautions
From the label.
Legal Status
Sold without a prescription.
Frequently Asked Questions
?What is bacitracin for?
Over-the-counter first aid: helping prevent infection in minor cuts, scrapes and burns, usually in a combination ointment with neomycin and polymyxin B.
?Does it work better than other options?
Not in the comparison we found. For clearing Staphylococcus aureus from the nose it cleared 44% against mupirocin's 94%.
?Is it safe?
It is a common cause of allergic contact dermatitis, and case reports describe genuine anaphylaxis after application to broken skin. Rare, but not theoretical.
?Why is it not injected?
Systemic bacitracin damages the kidneys, which is why injectable use was abandoned while the topical product stayed.
?Is it better than petroleum jelly for stitches?
Not clearly. In 922 patients after skin surgery, infection rates were 0.9% with bacitracin and 2.0% with plain white petrolatum, a non-significant difference, and only the bacitracin group developed allergic reactions.
?Is bacitracin still used in surgery?
Less so. Injectable bacitracin was recalled, and studies of breast-implant surgery found irrigating with it made no difference to infection rates.
References
- [fda-pi] Over-the-counter triple antibiotic ointment (bacitracin zinc, neomycin sulfate, polymyxin B sulfate) Drug Facts label, Uses and Directions (DailyMed, read October 1, 2026).
- [pubmed] Soto NE, et al. "Bacitracin versus mupirocin for Staphylococcus aureus nasal colonization." Infect Control Hosp Epidemiol, 1999;20(5):351-3. PMID: 10349956.
- [pubmed] Saryan JA, et al. "Anaphylaxis to topical bacitracin zinc ointment." Am J Emerg Med, 1998;16(5):512-3. PMID: 9725969.
- [pubmed] Vale MA, et al. "Bacitracin-induced anaphylaxis." Arch Dermatol, 1978;114(5):800. PMID: 348120.
- [pubmed] Andrews BJ, et al. "Chemotherapy for giardiasis: randomized clinical trial of bacitracin, bacitracin zinc, and a combination of bacitracin zinc with neomycin." Am J Trop Med Hyg, 1995;52(4):318-21. PMID: 7741168.
- [pubmed] Walton MA, et al. "The efficacy of Polysporin First Aid Antibiotic Spray (polymyxin B sulfate and bacitracin zinc) against clinical burn wound isolates." J Burn Care Rehabil, 1991;12(2):116-9. PMID: 2050717.
- [pubmed] Stone KJ, et al. "Mechanism of action of bacitracin: complexation with metal ion and C 55 -isoprenyl pyrophosphate." Proc Natl Acad Sci U S A, 1971;68(12):3223-7. PMID: 4332017.
- [clinical-trial] Dudley MN, et al. "Oral bacitracin vs vancomycin therapy for Clostridium difficile-induced diarrhea. A randomized double-blind trial." Arch Intern Med, 1986;146(6):1101-4. PMID: 3521518.
- [clinical-trial] Mondy KE, et al. "Evaluation of zinc bacitracin capsules versus placebo for enteric eradication of vancomycin-resistant Enterococcus faecium." Clin Infect Dis, 2001;33(4):473-6. PMID: 11462182.
- [clinical-trial] Smack DP, et al. "Infection and allergy incidence in ambulatory surgery patients using white petrolatum vs bacitracin ointment. A randomized controlled trial." JAMA, 1996;276(12):972-7. PMID: 8805732.
- [clinical-trial] Serena T, et al. "Bismuth subgallate/borneol (suile) is superior to bacitracin in the human forearm biopsy model for acute wound healing." Adv Skin Wound Care, 2007;20(9 Pt 1):485-92. PMID: 17762217.
- [clinical-trial] Videler WJ, et al. "Nebulized bacitracin/colimycin: a treatment option in recalcitrant chronic rhinosinusitis with Staphylococcus aureus? A double-blind, randomized, placebo-controlled, cross-over pilot study." Rhinology, 2008;46(2):92-8. PMID: 18575008.
- [clinical-trial] Nøhr M, et al. "Prophylactic single-dose fosfomycin and metronidazole compared with neomycin, bacitracin, metronidazole and ampicillin in elective colorectal operations." Acta Chir Scand, 1990;156(3):223-30. PMID: 2186587.
- [pubmed] Tirrell AR, et al. "Bacitracin for Injection Recall: Impact on Immediate Breast Implant Surgical Outcomes." Breast J, 2022;2022:1389539. PMID: 36105366.
- [pubmed] Roy N, et al. "Outcomes After Implant-Based Breast Reconstruction Following the National Institution of a Ban on Bacitracin Irrigation." Ann Plast Surg, 2024;92(4S Suppl 2):S191-S195. PMID: 38319958.
Sources & Citations
Studies were read from their PubMed abstracts; the OTC Drug Facts label was read on DailyMed October 1, 2026.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.