Cefaclor
CECLOR
Pronunciation: SEF-a-klor
What it isOral cephalosporin inhibiting bacterial penicillin-binding proteins; otitis and respiratory, urinary, or skin infections.
Why this oneIts unusually strong association with serum-sickness-like reactions, especially in children, distinguishes it from other cephalosporins.
What limits itFever, rash, and arthralgia should end treatment; renal impairment requires adjustment, and it lacks MRSA or pseudomonal coverage.
Cefaclor prescription history
Animated chart of estimated U.S. prescriptions per year, Antibacterials (systemic) (1938–2026). Cefaclor enters in 1979 (estimated).
Principal riskNo FDA boxed warning.
Classes and tags
Clinical profile
Legacy pregnancy categoryB
Defining liabilityAllergy, gastrointestinal effects and agent-specific renal, hepatic, hematologic or interaction risks.
FDA label
Read the full label on DailyMed ↗
NO BOXED WARNINGS
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Susceptible bacterial infections (usual) | Adults | 250 mg q8h | Doses may be doubled (500 mg q8h) for severe infections (e.g. pneumonia) or less susceptible organisms | |
| Susceptible bacterial infections (usual) | Pediatric | 20 mg/kg/day divided q8h | 40 mg/kg/day for more serious infections, otitis media, or less susceptible organisms; max 1 g/day |
Renal Dosage usually unchanged in impaired renal function
Hepatic Undefined
Instructions
- Oral
- beta-hemolytic streptococcal infections: treat at least 10 days
Available strengths
- cap 250, 500 mg
- susp 125, 187, 250, 375 mg/5 mL
- ER tab 375, 500 mg
Contraindications
- Known allergy to the cephalosporin group of antibiotics
Cautions
- Serum-sickness-like reactions (rash + arthritis/arthralgia ± fever), more frequent in pediatric patients and on second or subsequent courses
- Anaphylaxis may be more common with history of penicillin allergy
- Pseudomembranous colitis may occur during or after treatment
- Cephalosporins have triggered seizures, particularly in renal impairment without dose reduction — discontinue if seizures occur
Adverse reactions
- Hypersensitivity reactions ~1.5% (morbilliform eruptions 1/100; pruritus, urticaria, positive Coombs' each <1/200)
- Serum-sickness-like reactions (esp. pediatric, repeat courses)
- GI ~2.5%: diarrhea (1/70); nausea/vomiting rare
- Eosinophilia (1/50); genital pruritus, moniliasis or vaginitis (~1/50)
- Rare: SJS, TEN, anaphylaxis, transient hepatitis/cholestatic jaundice, thrombocytopenia, reversible interstitial nephritis, cytopenias
- Transient AST/ALT/alk phos elevations (1/40)
Pregnancy Category B — animal studies (up to 12x human dose) show no fetal harm; no adequate human studies; use only if clearly needed
Lactation Undefined
Cost
Generic entry1988
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Self-check
- Which reaction especially distinguishes cefaclor in children?
Serum-sickness-like reactions. - Which symptom triad should end cefaclor treatment?
Fever, rash and arthralgia.