What is the recommended dose of Cefixime (Cephalosporin) for treating Urinary Tract Infections (UTIs)?

Cefixime Dosing for Urinary Tract Infections

Standard Adult Dosing

For uncomplicated UTIs in adults, cefixime 400 mg once daily is the FDA-approved dose, though dividing this into 200 mg twice daily may reduce gastrointestinal side effects. 1

• The FDA label specifies 400 mg daily as the standard dose for adults, which can be administered as a single 400 mg capsule 1
• Clinical trials demonstrate that both 400 mg once daily and 200 mg twice daily achieve comparable efficacy, with bacteriologic eradication rates exceeding 94% in uncomplicated UTIs 2, 3
• The twice-daily regimen (200 mg every 12 hours) is preferable in clinical practice because it significantly reduces the incidence of diarrhea and gastrointestinal disturbances compared to once-daily dosing 2, 4

Treatment Duration

• Treat uncomplicated UTIs for 7-10 days 2, 4
• The European Association of Urology recommends 10 days for oral cephalosporins like cefpodoxime (a related agent), suggesting similar duration for cefixime 5

Pediatric Dosing (6 months and older)

• The FDA-approved dose is 8 mg/kg/day, administered either as a single daily dose or divided into 4 mg/kg every 12 hours 1
• Use the oral suspension formulation for children, as it achieves higher peak blood levels than tablets at equivalent doses 1
• Maximum daily dose should not exceed 400 mg 1

Renal Impairment Adjustments

• No dose adjustment needed for creatinine clearance ≥60 mL/min 1
• For CrCl 21-59 mL/min: reduce to 260 mg daily (13 mL of 100 mg/5 mL suspension or 6.5 mL of 200 mg/5 mL suspension) 1
• For CrCl ≤20 mL/min or patients on hemodialysis/peritoneal dialysis: reduce to 172 mg daily (8.6 mL of 100 mg/5 mL suspension or 4.4 mL of 200 mg/5 mL suspension) 1

Important Clinical Context and Limitations

When Cefixime is Appropriate

• Cefixime is effective for uncomplicated lower UTIs (cystitis) with clinical cure rates of 98% and bacteriologic eradication rates of 93-96% 6, 2, 3
• It demonstrates excellent activity against common uropathogens including E. coli, Proteus mirabilis, and Klebsiella species 2, 7

When Cefixime Should NOT Be Used

• Do NOT use cefixime for complicated UTIs or pyelonephritis 5, 8
• The European Association of Urology explicitly states that oral cephalosporins achieve significantly lower blood and urinary concentrations than intravenous routes, making them inadequate for complicated infections 5, 8
• For complicated UTIs, efficacy drops to only 57% compared to 98% for uncomplicated cases 6
• Avoid cefixime for pyelonephritis—fluoroquinolones (ciprofloxacin 500-750 mg twice daily) or parenteral cephalosporins are preferred 5

Critical Pitfalls to Avoid

• Do not substitute tablets/capsules for suspension in children with otitis media, as suspension achieves superior pharmacokinetics 1
• Cefixime has limited activity against Staphylococcus aureus and no activity against Pseudomonas aeruginosa 7
• In complicated UTIs with suspected multidrug-resistant organisms, cefixime is inadequate—use carbapenems, newer β-lactam/β-lactamase inhibitor combinations, or aminoglycosides instead 8, 9
• Resistance testing is essential before using cefixime in complicated UTIs, as gram-positive and non-fermenting organisms resistant to cefixime are common 4

Comparative Efficacy

• Cefixime demonstrates equivalent efficacy to trimethoprim-sulfamethoxazole in uncomplicated UTIs, with the advantage of once or twice-daily dosing versus twice-daily for TMP-SMX 2, 3
• In regions with high TMP-SMX resistance (approximately 24% of E. coli isolates in some studies), cefixime offers a reliable alternative 2