Amoxicillin-Clavulanate (Co-amoxiclav)
Tablet or syrup
Quick Summary
Clavulanic acid stops some bacteria from breaking down amoxicillin, so the combination works against more types of bacteria.
Medical Uses
How it's taken
Take it at the start of a meal to reduce stomach upset.
Take it for the full course, even if you feel better, unless your doctor tells you otherwise. Don't share antibiotics or keep leftovers.
Your doctor decides the right dose for you and how long to take it.
Your doctor decides the right dose for you. Follow their instructions and the label.
Common Side Effects
Diarrhoea
Common.
Nausea
And vomiting.
Thrush
Mouth or vaginal.
Interactions
Blood thinners
Clotting may need checks.
Methotrexate
Levels can rise.
Critical Warnings
Penicillin allergy
Black Box Warning: Don't take it if you're allergic to penicillin.
Liver problems
Rarely causes jaundice.
Severe allergic reaction
Black Box Warning: Swelling of the face or throat, difficulty breathing or a widespread rash: get emergency help.
Antibiotic resistance
Using antibiotics when they aren't needed makes them less effective for everyone.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.