Co-amoxiclav (Amoxicillin/Clavulanate)

How it works

Amoxicillin inhibits bacterial cell-wall synthesis by binding penicillin-binding proteins, while clavulanic acid irreversibly inactivates many bacterial beta-lactamases to protect amoxicillin from breakdown.

Prescribing in practice

• Co-amoxiclav is contraindicated in anyone with a history of penicillin anaphylaxis and in those with previous co-amoxiclav-associated jaundice or hepatic dysfunction.
• Cholestatic jaundice and hepatitis are recognised, may be delayed in onset and are more likely with longer courses and in older men.
• Its broad spectrum carries a relatively high risk of antibiotic-associated diarrhoea including Clostridioides difficile, so it should be reserved for appropriate indications.

Monitoring

Monitor liver function if treatment is prolonged or if jaundice or abdominal symptoms develop.

Counselling the patient

• Stop and seek advice if you develop a rash, jaundice or severe or bloody diarrhoea.
• Take it with food to reduce stomach upset and complete the prescribed course.

Evidence & guidelines

The hepatic and C. difficile risks of co-amoxiclav are well established and reflected in MHRA advice and antimicrobial stewardship guidance.