Vancomycin
Vancomycin hydrochloride
Also known as: Vancocin · vancomycini
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Confirmed bacteremia/septicemia for enterococci or staphylococci resistant to other commonly used antibiotics | 15 mg/kg IV over 30-60 minutes | IV | q6-8h | — | 🌎 NA |
| Serious infections | 15 mg/kg IV over 30-60 minutes | IV | q6h | — | 🌎 NA |
| C. difficile enterocolitis | 10-20 mg/kg PO | PO | q6h | 5-7 days | 🌎 NA |
| Skin, urinary, soft tissue infections | 10-20 mg/kg IV | IV | q12h | 7-10 days | 🌎 NA |
| Systemic infections, bacteremia | 15 mg/kg IV | IV | q6h | 10 days | 🌎 NA |
- Serious infections: For successful therapy, an aminoglycoside such as gentamicin or amikacin should also be administered.
- C. difficile enterocolitis: Oral vancomycin is not appreciably absorbed and is only effective for susceptible enteric infections.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Confirmed bacteremia/septicemia for enterococci or staphylococci resistant to other commonly used antibiotics | 15 mg/kg IV over 30-60 minutes | IV | q6-8h | — | 🌎 NA |
| Serious infections | 15 mg/kg IV over 30-60 minutes | IV | q6h | — | 🌎 NA |
- Serious infections: For successful therapy, an aminoglycoside such as gentamicin or amikacin should also be administered.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Vancomycin is a powerful, bactericidal glycopeptide antibiotic traditionally considered a "drug of last resort" in both human and veterinary medicine.
- Clinical Role: It is strictly reserved for severe, life-threatening infections caused by multi-drug resistant gram-positive bacteria, such as Methicillin-Resistant Staphylococcus aureus (MRSA), Methicillin-Resistant Staphylococcus pseudintermedius (MRSP), and multidrug-resistant Enterococcus species.
- Administration: For systemic infections, it must be administered intravenously (IV) as a slow infusion. Subcutaneous (SC) or intramuscular (IM) injections are strictly contraindicated due to severe tissue necrosis and pain.
- Oral Use: Because vancomycin is not absorbed through the gastrointestinal tract, oral administration is exclusively used to treat severe, localized enteric infections, specifically pseudomembranous colitis caused by Clostridium difficile.
Clinical Pearl: Due to the critical importance of vancomycin in treating life-threatening human infections, its use in veterinary medicine is highly controversial and should only be considered when culture and susceptibility testing confirm no other viable antibiotic options exist.
Mechanism of action
Vancomycin exerts its bactericidal effect primarily by inhibiting bacterial cell wall synthesis.
- Target Binding: It binds tightly and non-covalently to the D-alanyl-D-alanine terminus of cell wall precursor units.
- Inhibition: This massive steric hindrance prevents the enzymes (transglycosylases and transpeptidases) from incorporating the precursors into the growing peptidoglycan matrix → inhibition of cell wall cross-linking.
- Secondary Mechanisms: It also alters bacterial cell-membrane permeability and interferes with RNA synthesis, making resistance more difficult to develop.
- Spectrum: Activity is strictly limited to gram-positive organisms (staphylococci, streptococci, enterococci, Clostridium, Listeria). It is bactericidal against most susceptible bacteria but generally bacteriostatic against enterococci.
Safety & warnings
Contraindications
- Infections susceptible to other, lower-tier antibiotics
- Intramuscular (IM), Subcutaneous (SC), or Intraperitoneal (IP) administration
- Rapid IV bolus administration
Adverse effects
- Nephrotoxicity (especially with concurrent nephrotoxic drugs)
- Ototoxicity (hearing loss/vestibular signs)
- Thrombophlebitis (if given IV too rapidly)
- Severe hypotension or cardiac arrest (rare, associated with rapid IV bolus)
- Severe tissue damage and pain (if given IM, SC, or IP)
- Nausea and inappetence (with oral administration)
- Reversible neutropenia (with high/prolonged dosing)
- Hypersensitivity/dermatologic reactions (known in humans as 'Red Man Syndrome' due to histamine release)
Precautions
Must be administered IV over at least 30-60 minutes as a dilute solution to prevent thrombophlebitis and severe hypotension. Dosages must be reduced or dosing intervals increased in patients with renal dysfunction. Therapeutic drug monitoring (trough levels) is highly recommended. Strictly reserve for multi-drug resistant infections to prevent the emergence of Vancomycin-Resistant Enterococci (VRE) or Staphylococci (VRSA).
Drug interactions
Synergistic antibacterial effect, but significantly increases the risk of ototoxicity and nephrotoxicity. Enhanced monitoring is required.
May cause erythema and histamine-like flushing (reported in human pediatric patients).
Increased risk of severe nephrotoxicity; use together with extreme caution.
Monitoring
- Renal function (BUN, Creatinine, Urinalysis) at baseline and periodically during treatment
- Vancomycin serum trough levels (maintain above 5 mcg/mL; some specialists recommend 10-15 mcg/mL)
- Periodic Complete Blood Count (CBC) if therapy is prolonged (to monitor for neutropenia)
- Hearing and vestibular function (clinical observation)
Pharmacokinetics
Half-life
Absorption
Not appreciably absorbed when given orally. Oral administration only achieves local therapeutic concentrations in the GI tract.
Distribution
Widely distributed after intravenous administration. Therapeutic levels can be found in pleural, ascitic, pericardial, and synovial fluids. Does not readily distribute into the cerebrospinal fluid (CSF) at usual serum levels.
Metabolism
Undergoes minimal hepatic metabolism.
Elimination
Eliminated primarily unchanged via glomerular filtration in the kidneys; small amounts are excreted into the bile. Prolonged dosing or renal impairment can cause significant drug accumulation.
Overdose
Patients with severe colitis taking an oral overdose could potentially absorb enough drug to cause systemic adverse effects. Intravenous overdoses significantly increase the risk of ototoxicity (hearing/balance damage) and nephrotoxicity (kidney damage).
- Toxicity Data: The IV LD50 in mice is 400 mg/kg and in rats is 319 mg/kg.
- Treatment: Treatment is primarily supportive care. Hemodialysis does not appear to remove the drug in significant amounts.
Available products
Formulations
- Oral capsules
- Powder for injection solution
Human-labeled
- Vancomycin HCl Oral Capsules: 125 mg & 250 mg (Vancocin)
- Vancomycin HCl Powder for Injection Solution: 500 mg, 750 mg, 1 gram, 5 grams, & 10 grams
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store unmixed powder/capsules at room temperature in tight containers, protected from light. Once reconstituted, injectable or oral solutions are stable for 14 days if refrigerated. If further diluted for IV use (with D5W or 0.9% NaCl), solutions are stable for 24 hours at room temperature and 2 months if refrigerated.
Client information
Vancomycin is a highly specialized antibiotic reserved for very serious infections.
- Hospital Care (IV): If your pet is receiving this medication by injection, it will be done in the hospital because it must be given slowly into a vein to prevent severe reactions.
- Home Care (Oral): If you are sent home with oral vancomycin, it is specifically to treat a severe intestinal infection (like C. difficile).
- Administration: Give the oral medication exactly as prescribed by your veterinarian. Do not skip doses or stop early, even if your pet seems better, to prevent the bacteria from becoming resistant.
- Food: You may give the oral capsules/liquid with a small amount of food if it upsets your pet's stomach.
- Side Effects: Watch for and report any signs of nausea, loss of appetite, vomiting, or changes in urination.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.