First-lineKeflex
Cephalexin
1st-generation cephalosporin (oral)
Oral step-down for UTI, cellulitis & wound infection in pregnancy.
Oral
First-line for
- Uncomplicated UTI in pregnancy
- Skin/soft-tissue infection (cellulitis)
- Streptococcal pharyngitis
- Oral step-down after cefazolin
Mechanism
Oral β-lactam; binds PBPs — strong Gram-positive (strep, MSSA), modest Gram-neg cover.
“Oral cousin of cefazolin”
- 500 mg QDS × 7 d for UTI
- Culture-guided where possible
Dosing
- UTI
- 500 mg PO QDS × 7 d
- SSTI
- 250–500 mg PO QDS
Contraindications
- AbsoluteCephalosporin / severe penicillin anaphylaxis
- CautionRenal impairment — dose adjust
Side effects
- GI upset
- Rash
- Vaginal candidiasis
Fetal & maternal notes
- • Safe T1–T3 and in lactation
Key interactions
Probenecid
OK↑ levels
Metformin
CautionMild ↑ levels
Clinical pearls
- 💡 Excellent step-down from IV cefazolin
- 💡 Resistance rising in E. coli — culture-guided dosing key
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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