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Cefalexin ๐
โ ๏ธ About 1โ6% of penicillin-sensitive patients are also allergic to cephalosporins. Those with a history of immediate hypersensitivity to penicillin or other ฮฒ-lactams should not receive cefalexin. Use with caution in patients with mild sensitivity to ฮฒ-lactams.
๐ About Cefalexin
- Always check the BNF entry for up-to-date prescribing advice.
- First-generation cephalosporin (ฮฒ-lactam antibiotic).
- Commonly prescribed in the community for urinary tract, skin, and respiratory infections.
โ๏ธ Mode of Action
- Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs).
- Bactericidal activity against susceptible Gram-positive and some Gram-negative organisms.
๐ฏ Indications
- UTIs (esp. in pregnancy where nitrofurantoin unsuitable).
- Respiratory tract infections.
- Otitis media, sinusitis.
- Skin & soft tissue infections (e.g. cellulitis).
๐ Dose Summary
| Indication | Typical Adult Dose | Frequency | Route |
|---|---|---|---|
| General infections | 250โ500 mg | Every 8 hours (TDS) | Oral (PO) |
| Severe infections | Up to 1 g | Every 6 hours (QDS) | PO |
| Children | 25โ50 mg/kg/day | Divided in 2โ4 doses | PO (check BNFc) |
Adjust dose in renal impairment โ see BNF.
๐ Interactions
- See BNF.
- Potential interaction with metformin (risk of lactic acidosis via reduced clearance).
- Enhanced anticoagulant effect with warfarin.
โ ๏ธ Cautions
- History of penicillin allergy (cross-reactivity risk).
- Renal impairment (dose adjustment required).
- Risk of C. difficile infection with broad-spectrum antibiotic use.
๐ซ Contraindications
- Immediate hypersensitivity to penicillins or cephalosporins.
๐ฅ Side Effects
- Common: Diarrhoea, nausea, vomiting, abdominal pain, headache, rash.
- Serious: Clostridioides difficile diarrhoea, anaphylaxis, StevensโJohnson syndrome (rare).
๐ References
- BNF โ Cefalexin
- BNF for Children (BNFc) โ paediatric dosing
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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