Co-Amoxiclav

How it works

Amoxicillin inhibits bacterial cell-wall synthesis by binding penicillin-binding proteins, while clavulanic acid irreversibly inhibits beta-lactamase enzymes, protecting amoxicillin from degradation.

Prescribing in practice

• Cholestatic jaundice and hepatitis can occur, sometimes weeks after stopping, and are more common with prolonged treatment and in older men; it is contraindicated where there is a history of co-amoxiclav- or penicillin-associated jaundice.
• It is contraindicated in penicillin hypersensitivity and shares cross-reactivity with cephalosporins.
• Reserve for infections likely to be caused by resistant organisms because broad-spectrum use promotes resistance and Clostridioides difficile infection.

Monitoring

Monitor hepatic function in prolonged courses and remain alert for diarrhoea suggesting C. difficile infection.

Counselling the patient

• Report yellowing of the skin or eyes, dark urine or pale stools.
• Seek advice for severe or bloody diarrhoea.
• Complete the prescribed course and report any rash or breathing difficulty.

Evidence & guidelines

NICE antimicrobial guidance positions co-amoxiclav as a reserve agent for specific indications rather than routine first-line empirical use.