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Beta-lactam + beta-lactamase inhibitor Pregnancy: Use only if benefit outweighs risk; may be associated with necrotising enterocolitis in preterm neonates (ORACLE trial).

Co-amoxiclav (Amoxicillin/Clavulanate)

Brand names: Augmentin

Adult dose

Dose: 375–625 mg every 8 hours oral; 1.2 g every 8 hours IV
Route: Oral or IV
Frequency: Every 8 hours (oral); every 6–8 hours (IV)
Max: 3.6 g/day IV (6 × 600 mg); 1875 mg/day oral
Mild-moderate infections: 375 mg (250/125) or 625 mg (500/125) every 8 hours oral for 5–7 days. IV: 1.2 g (1 g/200 mg) every 8 hours. Hospital-acquired pneumonia: 1.2 g TDS IV. Surgical prophylaxis: 1.2 g IV at induction.

Paediatric dose

Dose: 25 mg/kg
Route: Oral or IV
Frequency: Three times daily
Max: 625 mg/dose oral; 1.2 g/dose IV
Concentration: 125 mg/ml
Oral (125/31 suspension): 1 month–1 year 0.25 mL/kg TDS; 1–6 years 5 mL TDS (250/62 suspension). IV: 30 mg/kg TDS (max 1.2 g).

Dose adjustments

Renal

If eGFR <30: increase interval (every 12 hours); avoid if eGFR <10.

Hepatic

Use with caution in hepatic disease — hepatotoxicity risk with clavulanate.

Paediatric weight-based calculator

Oral (125/31 suspension): 1 month–1 year 0.25 mL/kg TDS; 1–6 years 5 mL TDS (250/62 suspension). IV: 30 mg/kg TDS (max 1.2 g).

Clinical pearls

  • Clavulanate inhibits beta-lactamases — active against beta-lactamase producing S. aureus, H. influenzae, Moraxella
  • Cholestatic hepatitis more common in older males, especially on long courses — avoid in patients with prior jaundice
  • First-choice for bite wounds (human, animal), acute exacerbations of COPD
  • Surgically administered IV dose at induction reduces SSI

Contraindications

  • Penicillin hypersensitivity
  • History of co-amoxiclav-associated jaundice / hepatic dysfunction
  • Infectious mononucleosis

Side effects

  • GI upset and diarrhoea (more than amoxicillin alone)
  • Cholestatic jaundice (delayed — up to 6 weeks post-treatment)
  • Rash
  • Hypersensitivity / anaphylaxis
  • Antibiotic-associated colitis

Interactions

  • Warfarin — may increase INR
  • Methotrexate — reduced excretion
  • Allopurinol — increased risk of rash

Monitoring

  • LFTs (prolonged use or if jaundice develops)
  • Response to treatment
  • C. difficile risk

Reference: BNFc; BNF; NICE NG15 Surgical Site Infections; PHE guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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