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Beta-lactam + beta-lactamase inhibitor antibiotic Pregnancy: Use with caution — amoxicillin is safe; clavulanate data limited. Avoid in threatened preterm labour (possible NEC association in neonates).

Co-amoxiclav 625mg (Augmentin)

Brand names: Augmentin

Adult dose

Dose: 625 mg (amoxicillin 500mg / clavulanate 125mg) three times daily for 5–7 days
Route: Oral
Frequency: Three times daily
Max: 625 mg TDS (standard ENT); 1 g TDS in severe infections
ENT indications: acute otitis media (treatment failure after amoxicillin 48–72 hours), acute rhinosinusitis with systemic features, peritonsillar abscess (alongside drainage), dental-origin ENT infections. Take with food to reduce GI side effects. Cover for H. influenzae and M. catarrhalis (beta-lactamase producers) that amoxicillin fails against.

Paediatric dose

Dose: 40 mg/kg
Route: Oral
Frequency: Three times daily
Max: 625 mg/dose
Concentration: 125 mg/ml
Oral suspension: 125/31 (125mg amoxicillin/31.25mg clavulanate per 5mL) or 250/62. Standard dose: 40 mg/kg/day (amoxicillin component) in 3 divided doses. High dose for resistant AOM: 90 mg/kg/day. Age <3 months: specialist advice. Take with food.

Dose adjustments

Renal

eGFR 10–30: 375 mg (250/125) every 12 hours. eGFR <10: avoid or use under specialist guidance.

Hepatic

Use with caution in hepatic impairment — hepatotoxicity risk (monitor LFTs). Avoid if history of co-amoxiclav-related cholestatic jaundice.

Paediatric weight-based calculator

Oral suspension: 125/31 (125mg amoxicillin/31.25mg clavulanate per 5mL) or 250/62. Standard dose: 40 mg/kg/day (amoxicillin component) in 3 divided doses. High dose for resistant AOM: 90 mg/kg/day. Age <3 months: specialist advice. Take with food.

Clinical pearls

  • First-line treatment failure antibiotic for AOM when initial amoxicillin has failed (covers beta-lactamase producers)
  • GI side effects are significantly higher than amoxicillin due to clavulanate — take with food, probiotic may help
  • Cholestatic hepatitis risk increases with longer courses and in elderly — warn patients to report jaundice
  • If penicillin-allergic: doxycycline or clarithromycin are alternatives for ENT infections
  • For AOM with effusion alone (glue ear): antibiotics not indicated — watchful waiting

Contraindications

  • Penicillin hypersensitivity
  • Previous co-amoxiclav-associated cholestatic jaundice or hepatic dysfunction
  • Infectious mononucleosis (rash risk)

Side effects

  • Diarrhoea (common — clavulanate related)
  • Nausea and vomiting
  • Rash (maculopapular)
  • Cholestatic jaundice / hepatitis (rare but well-recognised — more than amoxicillin alone)
  • Oral/vaginal candidiasis
  • Clostridium difficile colitis (uncommon)

Interactions

  • Warfarin — may increase INR (monitor closely)
  • Methotrexate — reduced renal excretion of methotrexate
  • Oral contraceptives — theoretical reduction in efficacy (advise barrier method)

Monitoring

  • Clinical response at 48–72 hours
  • LFTs if prolonged course or prior hepatic history

Reference: BNFc; BNF; NICE NG98 AOM; NICE NG120 Sinusitis; PHE Antibiotic 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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