Penicillin antibioticPrescription only

Amoxicillin

Capsule, tablet or liquid

Quick Summary

Amoxicillin is a penicillin antibiotic that kills bacteria. It works only for bacterial infections; it doesn't work for viral infections such as colds and flu.

Chest infections
Ear, nose and throat infections
Urinary tract infections
Dental infections

Medical Uses

Chest infections: Such as pneumonia.
Ear, nose and throat infections: Such as some ear and sinus infections.
Urinary tract infections: Bladder and kidney infections caused by bacteria.
Dental infections: Infections around the teeth.
Stomach ulcers: With other medicines, to clear H. pylori bacteria.

How it's taken

Amoxicillin is usually taken several times a day, spaced evenly, with or without food. The liquid form is often used for children. Your doctor decides the right dose for you and may change it over time.

Finish the whole course, even if you feel better, unless your doctor tells you to stop. Don't share antibiotics or keep leftovers.

Your doctor decides the right dose for you. Follow their instructions and the label.

Common Side Effects

Feeling sick or diarrhoea

Common and usually mild. Drink plenty of fluids.

Rash

A mild rash can happen. Tell your doctor, as it can sometimes mean an allergy.

Thrush

Antibiotics can sometimes cause thrush in the mouth or vagina.

Interactions

Methotrexate

Amoxicillin can increase methotrexate levels.

Blood thinners (such as warfarin)

Your blood clotting may need closer checks.

Combined contraceptive pill

Severe diarrhoea or vomiting can stop the pill working; use extra protection if this happens.

Critical Warnings

Penicillin allergy

Black Box Warning: Don't take amoxicillin if you're allergic to penicillin. Get emergency help for swelling of the face or throat, trouble breathing or a severe rash.

Severe or bloody diarrhoea

Can be a sign of a serious bowel infection. Contact a doctor straight away.

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.