What is the recommended dose of oral vancomycin (Vancomycin hydrochloride) for adults?

Oral Vancomycin Dosing for Adults

For initial or severe Clostridioides difficile infection (CDI), the recommended dose is vancomycin 125 mg orally four times daily for 10 days, while fulminant CDI requires a higher dose of 500 mg orally four times daily. 1, 2

Dosing by Disease Severity

Non-Severe and Severe CDI (Initial Episode)

• Vancomycin 125 mg orally four times daily for 10 days is the standard dose 1, 3, 2
• Non-severe CDI is defined as WBC ≤15,000 cells/mL and serum creatinine <1.5 mg/dL 1, 3
• Severe CDI is defined as WBC ≥15,000 cells/mL or serum creatinine >1.5 mg/dL 1, 3
• The 125 mg dose is equally effective as higher doses (250-500 mg) for non-fulminant disease and is preferred due to lower cost 1, 4

Fulminant CDI

• Vancomycin 500 mg orally four times daily is required for fulminant disease 1
• Fulminant CDI is characterized by hypotension, shock, ileus, or megacolon 1, 3
• If ileus is present, add rectal vancomycin 500 mg in 100 mL normal saline every 6 hours as retention enema 1
• Concurrent intravenous metronidazole 500 mg every 8 hours should be administered with oral/rectal vancomycin when ileus is present 1

Recurrent CDI Dosing

First Recurrence

• Vancomycin 125 mg four times daily for 10 days if metronidazole was used initially 1
• Tapered and pulsed vancomycin regimen if standard vancomycin was used initially: 125 mg four times daily for 10-14 days, then twice daily for 7 days, then once daily for 7 days, then every 2-3 days for 2-8 weeks 1

Second or Subsequent Recurrence

• Tapered and pulsed vancomycin regimen (as above) 1
• Alternative: Vancomycin 125 mg four times daily for 10 days followed by rifaximin 400 mg three times daily for 20 days 1

Staphylococcal Enterocolitis

• Total daily dose of 500 mg to 2 g orally in 3-4 divided doses for 7-10 days 2
• This indication is distinct from CDI and requires higher total daily dosing 2

Important Clinical Considerations

Common Pitfalls to Avoid:

• Do not use higher doses (250-500 mg four times daily) routinely for non-fulminant CDI, as 125 mg is equally effective and less expensive 1, 4
• However, research suggests that patients not responding to conventional doses within 72 hours may benefit from dose escalation to 500 mg four times daily 5
• Avoid metronidazole as first-line therapy due to inferior efficacy and risk of cumulative neurotoxicity 1, 3

Monitoring Considerations:

• Patients >65 years have increased risk of nephrotoxicity and require renal function monitoring during and after treatment 2
• Patients with inflammatory bowel disorders or renal insufficiency may have significant systemic absorption and warrant serum vancomycin monitoring 2
• Faecal vancomycin levels are proportional to dose administered, with even 125 mg achieving levels far exceeding the MIC90 against C. difficile 6

Duration of Therapy:

• Standard duration is 10 days, though some patients may require extension to 14 days if response is delayed 1
• For secondary prophylaxis in frequently relapsing patients who cannot receive fecal microbiota transplantation, vancomycin 125 mg once daily can be used long-term 7