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
