Vancomycin
The hospital antibiotic for resistant staphylococci, given into a vein, and for C. difficile, given by mouth
Vancomycin is a glycopeptide antibiotic with two separate lives. Given intravenously it treats serious infections with methicillin-resistant staphylococci; given by mouth it stays in the gut and treats C. difficile diarrhoea. Its dosing is now guided by drug levels, and newer drugs have beaten it in some head-to-head trials.
What is it?
Vancomycin's intravenous label reserves it for serious infections with methicillin-resistant staphylococci, for patients allergic to penicillin, and for organisms resistant to other drugs. The two routes do not substitute for each other: the oral capsule label says intravenous vancomycin does not work for C. difficile, and oral vancomycin does not work for infections outside the gut.
The labels set simple starting doses. Intravenously, adults usually get 2 g a day, as 500 mg every six hours or 1 g every twelve, each dose infused at no more than 10 mg a minute or over at least an hour, because fast infusion causes reactions; children get 10 mg/kg every six hours. By mouth for C. difficile, adults take 125 mg four times a day for 10 days, and children 40 mg/kg a day in divided doses, never more than 2 g.
Dosing it well is a craft. It is cleared by the kidneys, with a half-life of 4 to 6 hours when they work normally and about 7.5 days in people without kidney function. The 2020 consensus guideline replaced trough-level monitoring, linked to more kidney injury, with a target of 400 to 600 for the 24-hour exposure relative to the bacterium's sensitivity.
Its main hazard is the kidney. The intravenous label says the risk of acute kidney injury rises with exposure and asks for kidney monitoring, especially alongside other nephrotoxic drugs; it also warns of hearing damage, severe skin reactions and a rare retinal vasculitis. A 2025 network meta-analysis of 70 studies (76,638 patients, most of them observational) found vancomycin with piperacillin-tazobactam carried about 2.5 times the odds of kidney injury of vancomycin with cefepime or meropenem, without differences in dialysis or death.
Its head-to-head record is mixed. In MRSA pneumonia, linezolid cured more patients and caused less kidney injury. For C. difficile, fidaxomicin matched its cure rate with fewer recurrences, and a Norwegian trial found faecal microbiota transplantation non-inferior to it for first episodes.
For C. difficile its standing rests partly on an older trial. In a 2007 study stratified by severity, vancomycin and metronidazole cured mild disease about equally (98% against 90%), but in severe disease vancomycin cured 97% against 76%; recurrence was similar. Adding a beta-lactam to vancomycin or daptomycin for MRSA bloodstream infection in the CAMERA2 trial did not improve the main outcome and more than tripled kidney injury.
Oral vancomycin as prevention during other antibiotic courses lowered recurrence in a small trial without reaching significance, and doubled carriage of vancomycin-resistant enterococci.
Mechanism of Action
Vancomycin is a glycopeptide that blocks cell-wall building in gram-positive bacteria; it is poorly absorbed by mouth, so the oral and intravenous forms treat different infections.
Gram-positive cell wall
Its activity against methicillin-resistant staphylococci is why the intravenous label reserves it for serious resistant infections.
Stays in the gut by mouth
Poorly absorbed orally, it reaches high faecal levels with no blood levels detected in volunteers, which is why the capsules treat C. difficile and nothing else (label).
Kidney clearance
Half-life 4 to 6 hours with normal kidneys and about 7.5 days without kidney function, so doses follow kidney function and levels.
Published Research
The studies behind vancomycin, read from their PubMed abstracts: dosing, MRSA and C. difficile trials, combinations, and kidney injury.
How to dose it
The revised US consensus guideline for serious MRSA infections dropped trough monitoring, linked to more kidney injury, for a target ratio of 400 to 600 mg·h/L for 24-hour exposure relative to the bacterium's MIC.
Against linezolid in MRSA pneumonia
In ZEPHyR, linezolid cured 57.6% against 46.6% on dose-optimised vancomycin in proven MRSA hospital pneumonia, and kidney injury affected 8.4% against 18.2%.
CAMERA2: adding a beta-lactam in MRSA bacteremia
In 352 adults, adding an anti-staphylococcal beta-lactam to vancomycin or daptomycin did not improve the main combined outcome; acute kidney injury was 23% against 6%, and the trial stopped early on safety grounds.
Kidney injury with piperacillin-tazobactam
A network meta-analysis of 70 studies (76,638 patients) found higher odds of acute kidney injury with vancomycin plus piperacillin-tazobactam than with cefepime (OR 2.55) or meropenem (OR 2.26), with no difference in dialysis, mortality or length of stay.
Against fidaxomicin in C. difficile
629 adults with C. difficile infection took fidaxomicin or oral vancomycin for 10 days. Cure was similar, 88.2% against 85.8%, but recurrence was lower on fidaxomicin, 15.4% against 25.3%.
Against metronidazole, by C. difficile severity
Among 150 patients who completed the trial, mild disease was cured in 98% on vancomycin and 90% on metronidazole (P = 0.36); severe disease in 97% against 76% (P = 0.02). Recurrence was 14% against 15%.
Against faecal transplant
In 100 Norwegian adults with a first C. difficile episode, cure without recurrence within 60 days came in 66.7% after faecal microbiota transplantation and 61.2% after vancomycin, meeting non-inferiority.
As prevention
81 adults with recent C. difficile who needed other antibiotics took oral vancomycin 125 mg daily or placebo. Recurrence was 43.6% against 57.1%, not significant, and resistant-enterococcus carriage was 50.0% against 24.0%.
Dosing Data
Vancomycin is infused intravenously for systemic infections or taken by mouth for gut infections; the labels give starting doses that are then adjusted.
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 trials above, the Vancomycin Hydrochloride for Injection prescribing information (Mylan Institutional; DailyMed set 2dc7b3d6, version 10, effective June 1, 2021) and the Vancocin capsules prescribing information (DailyMed set a078d9c2, version 12, effective December 22, 2025).
Contraindications & Cautions
From the labels.
Legal Status
Vancomycin is FDA-approved in intravenous and oral forms.
Frequently Asked Questions
?What is vancomycin used for?
Intravenously for serious infections with resistant staphylococci; by mouth for C. difficile diarrhoea and staphylococcal enterocolitis.
?Why are blood levels checked?
Too little fails and too much injures the kidneys. Guidelines now target 24-hour exposure rather than trough levels.
?Is it still the best option for C. difficile?
Fidaxomicin cured as often with fewer recurrences, and faecal transplant was non-inferior for first episodes.
?How long does it last in the body?
4 to 6 hours with normal kidneys, and about 7.5 days without kidney function, according to the label.
?What dose is used?
Intravenously, usually 2 g a day for adults (500 mg every 6 hours or 1 g every 12), adjusted to kidney function and drug levels; by mouth for C. difficile, 125 mg four times a day for 10 days.
?Is it hard on the kidneys?
It can be: the label says kidney injury risk rises with exposure, and observational data show more injury when it is combined with piperacillin-tazobactam than with cefepime or meropenem.
?Is it better than metronidazole for C. difficile?
For severe disease, yes in a 2007 trial (97% against 76% cure); for mild disease the two were similar.
References
- [fda-pi] Vancomycin Hydrochloride for Injection (Mylan Institutional) Prescribing Information, sections Indications, Dosage and Clinical Pharmacology (DailyMed version 10, effective June 1, 2021; read September 30, 2026).
- [fda-pi] VANCOCIN (vancomycin hydrochloride) capsules Prescribing Information, sections 1 and 2 (DailyMed version 12, effective December 22, 2025; read September 30, 2026).
- [pubmed] Rybak MJ, et al. "Therapeutic Monitoring of Vancomycin for Serious Methicillin-resistant Staphylococcus aureus Infections: A Revised Consensus Guideline and Review by the American Society of Health-system Pharmacists, the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the Society of Infectious Diseases Pharmacists." Clin Infect Dis, 2020;71(6):1361-1364. PMID: 32658968.
- [pubmed] Chavanet P. "The ZEPHyR study: a randomized comparison of linezolid and vancomycin for MRSA pneumonia." Med Mal Infect, 2013;43(11-12):451-5. PMID: 24238896.
- [pubmed] Tong SYC, et al. "Effect of Vancomycin or Daptomycin With vs Without an Antistaphylococcal β-Lactam on Mortality, Bacteremia, Relapse, or Treatment Failure in Patients With MRSA Bacteremia: A Randomized Clinical Trial." JAMA, 2020;323(6):527-537. PMID: 32044943.
- [pubmed] Pan K, et al. "Vancomycin combined with piperacillin/tazobactam increases the risk of acute kidney injury compared with vancomycin plus other anti-pseudomonal beta-lactams: a systematic review and network meta-analysis." J Antimicrob Chemother, 2025;80(1):47-58. PMID: 39533846.
- [pubmed] Louie TJ, et al. "Fidaxomicin versus vancomycin for Clostridium difficile infection." N Engl J Med, 2011;364(5):422-31. PMID: 21288078.
- [pubmed] Zar FA, et al. "A comparison of vancomycin and metronidazole for the treatment of Clostridium difficile-associated diarrhea, stratified by disease severity." Clin Infect Dis, 2007;45(3):302-7. PMID: 17599306.
- [pubmed] Juul FE, et al. "Fecal Microbiota Transplantation Versus Vancomycin for Primary Clostridioides difficile Infection : A Randomized Controlled Trial." Ann Intern Med, 2025;178(7):940-947. PMID: 40523286.
- [pubmed] Keating JA, et al. "Oral Vancomycin for Prevention of Recurrent Clostridioides difficile Infection: A Randomized Clinical Trial." JAMA Netw Open, 2025;8(7):e2517834. PMID: 40601321.
- [other] US FDA, Drugs@FDA (openFDA): VANCOCIN HYDROCHLORIDE capsules, NDA 050606, ANI Pharmaceuticals, prescription. Read September 30, 2026.
Sources & Citations
Studies were read from their PubMed records (October 5, 2026); the labels and Drugs@FDA are listed below with their read dates.
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.