What is the recommended dose of Cefixime (third-generation cephalosporin antibiotic) for an adult or adolescent with an uncomplicated urinary tract infection (UTI)?

Cefixime Dosing for Urinary Tract Infections

For uncomplicated UTIs in adults, cefixime 400 mg daily (either as a single dose or 200 mg twice daily) is the FDA-approved regimen, though it should be considered a second-line option reserved for situations where first-line agents cannot be used. 1

Standard Adult Dosing

• The FDA-approved dose is 400 mg daily, which can be administered as a single 400 mg dose or divided as 200 mg twice daily 1
• This dosing applies specifically to uncomplicated urinary tract infections caused by E. coli and Proteus mirabilis 1
• The capsule may be taken without regard to food 1

Pediatric Dosing (6 months or older)

• The recommended pediatric dose is 8 mg/kg/day of the oral suspension 1
• This can be given as a single daily dose or divided into 4 mg/kg every 12 hours 1
• Children weighing more than 45 kg or older than 12 years should receive the adult dose of 400 mg daily 1

Renal Impairment Adjustments

• Normal dosing (400 mg daily) can be used when creatinine clearance is ≥60 mL/min 1
• For creatinine clearance 21-59 mL/min or patients on hemodialysis: 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 creatinine clearance ≤20 mL/min or continuous 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
• Neither hemodialysis nor peritoneal dialysis removes significant amounts of cefixime from the body 1

Critical Clinical Context and Limitations

Cefixime should NOT be first-line therapy for uncomplicated UTIs. The 2024 WHO guidelines and recent consensus statements recommend nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin as preferred first-choice agents 2, 3, 4

When to Consider Cefixime:

• Use only when first-line agents are contraindicated, unavailable, or based on culture sensitivities showing resistance to preferred agents 3, 4
• Local resistance rates should be <20% for empiric use 3, 4
• Ensure the infection is caused by susceptible organisms (E. coli or Proteus mirabilis) 1

Critical Contraindications and Warnings:

• NEVER use cefixime for pyelonephritis or febrile UTIs—it does not achieve adequate blood and tissue concentrations for kidney infections 3, 4, 5
• Cefixime is inactive against Pseudomonas, Enterococcus, MRSA, most Enterobacter species, and ESBL-producing organisms 3, 4
• The WHO specifically recommends avoiding cefixime for uncomplicated cystitis due to lack of supporting evidence 4

Treatment Duration

• For uncomplicated cystitis: 7 days is the standard duration when β-lactams are used 2
• Clinical trials showed efficacy rates of 98% in acute uncomplicated cystitis with 200-400 mg daily dosing 6
• For complicated UTIs: 57% efficacy rate was observed, significantly lower than for uncomplicated infections 6

Comparative Efficacy Evidence

• Cefixime demonstrated comparable efficacy to co-trimoxazole and amoxicillin in acute uncomplicated UTIs in comparative trials 7
• The drug shows 93% bacterial eradication in uncomplicated UTIs but only 72% in complicated UTIs 6
• β-lactams including cefixime have inferior efficacy compared to fluoroquinolones and cause more adverse effects 2, 4

Common Pitfalls to Avoid

• Do not substitute cefixime for first-line agents without documented contraindications or resistance 3, 4
• Never use for suspected kidney involvement—this is a critical safety issue 3, 4
• Avoid once-daily 400 mg dosing if gastrointestinal tolerance is a concern; twice-daily 200 mg dosing shows lower incidence of GI adverse effects 8
• Do not initiate therapy for complicated UTIs without culture and sensitivity testing 8
• Remember that cefixime causes collateral damage to protective periurethral and vaginal microbiota, potentially promoting more rapid UTI recurrence 4

Adverse Effects Profile

• Most common adverse effects are diarrhea and stool changes, usually mild to moderate and transient 7
• Gastrointestinal discomfort occurs in approximately 1.7% of patients 6
• Adverse effects typically occur in the first few days of treatment 7
• Abnormal laboratory findings (elevated liver enzymes, bilirubin, leukocytes) may occur but typically resolve after discontinuation 6