What is the typical duration of an antibiotic course?

Antibiotic Duration for Common Infections

For most common bacterial infections in clinically stable patients, shorter antibiotic courses of 5-7 days are as effective as traditional 10-14 day courses and should be the standard of care. 1

General Principles

Shorter courses (3-7 days) achieve equivalent clinical outcomes to longer durations while reducing adverse events, antimicrobial resistance, and costs. 1, 2 The key requirements are:

• Clinical stability is mandatory before stopping therapy, including resolution of vital sign abnormalities, ability to eat, and normal mentation for pneumonia, or being afebrile for 48 hours for bacteremia 1
• Appropriate antimicrobial selection at therapeutic doses is essential—short courses only work when correct antibiotics are used 1
• Adequate source control must be achieved for intra-abdominal infections and bacteremia before considering short durations 1

Infection-Specific Durations

Community-Acquired Pneumonia (CAP)

Treat for 3-5 days once clinically stable (resolution of vital signs, ability to eat, normal mentation). 1, 2 Short courses (≤6 days) demonstrate 27% fewer serious adverse events (risk ratio 0.73) and 48% lower mortality (risk ratio 0.52) compared to longer courses. 2 Even in moderate-to-severe CAP, 3 days of β-lactam therapy is non-inferior to 8 days. 2

Ventilator-Associated Pneumonia (VAP)

Treat for 7-8 days. 1, 2 Eight-day regimens show no difference in mortality, pulmonary infection recurrence, or clinical cure compared to 15-day regimens, even for non-fermenting gram-negative bacteria. 2

Urinary Tract Infections

• Uncomplicated cystitis in women: 3-5 days with first-line agents (nitrofurantoin, TMP-SMX, fosfomycin) 1
• Complicated UTI and pyelonephritis in women: 5-7 days with appropriate antimicrobials 1, 2
• Male UTIs: 7 days in stable patients, extending to 14 days only if prostatitis cannot be excluded 1, 2

Eight RCTs including >1,300 patients confirmed that 5-7 day therapy results in similar clinical success as 10-14 day therapy, even in patients with bacteremia. 2

Intra-Abdominal Infections

Treat for 4 days after adequate source control. 1, 2 Four-day courses show no difference in surgical site infection (6.6% vs 8.8%), recurrent infection (13.8% vs 15.6%), or death (0.8% vs 1.2%) compared to continuing until 2 days after resolution of signs (mean 8 days). 2

Gram-Negative Bacteremia

Treat for 7 days when diagnosis is confirmed, appropriate antimicrobials are used, and patients show clinical improvement. 1, 2 Seven-day courses are non-inferior to 14-day courses with similar clinical failure rates (2.4-6.6%). 1 This was demonstrated in a large RCT of 604 patients with gram-negative bacteremia from various sources (UTI, IAI, respiratory tract, central line, skin/soft tissue). 2

A 2024 multicenter trial of 3,608 hospitalized patients with bloodstream infections (excluding S. aureus and severe immunosuppression) showed 7 days was non-inferior to 14 days, with 90-day mortality of 14.5% vs 16.1% (difference -1.6 percentage points). 3

Skin and Soft Tissue Infections

Treat for 5-6 days in improving patients receiving appropriate antibiotics. 1, 2 Five RCTs involving 1,478 patients demonstrate short-course treatment is non-inferior to long-course. 1 For nonpurulent cellulitis specifically, use 5-6 days of antibiotics active against streptococci. 2

Bone and Joint Infections

For osteomyelitis (native bone): 6 weeks after surgical debridement in the absence of implanted foreign bodies. 1, 2 Six weeks is non-inferior to 12 weeks for vertebral osteomyelitis without surgical debridement (90.9% vs 90.8% clinical cure). 1

For prosthetic joint infection: 12 weeks following surgical intervention. 1 Six weeks is inferior to 12 weeks for hip/knee PJI (18.1% vs 9.4% persistent infection, risk difference 8.7%). 1

Diabetic Foot Infections

Duration depends on severity: 2

• Mild infections: 1-2 weeks, with some requiring an additional 1-2 weeks 2
• Moderate and severe infections: 2-4 weeks, depending on structures involved, adequacy of debridement, and wound vascularity 2
• Osteomyelitis: at least 4-6 weeks, but shorter if entire infected bone is removed, longer if infected bone remains 2

Critical Pitfalls to Avoid

Do not default to 10-day courses regardless of infection type—this is the most common error in antibiotic prescribing. 2 Many physicians prescribe longer durations believing it prevents resistance, but prolonged antibiotic use actually increases resistance through selection pressure. 2

Do not continue antibiotics until wound healing is complete—treat until infection resolves, not until wounds heal. 2 This is particularly important for diabetic foot infections where wound healing may take weeks beyond infection resolution.

Do not use microbiological criteria alone to justify prolonged courses—clinical cure does not equate to microbiological eradication. 4 Persistent colonization after clinical improvement does not require continued antibiotics.

Do not treat colonization—sterile invasive cultures with clinical improvement warrant stopping antibiotics. 4 A large study of 4 million infection episodes found that longer courses (8-15 days) were associated with 75% higher risk of infection-related complications compared to shorter courses, with no additional effectiveness. 5