How long does amoxicillin take to work?
Last updated September 3, 2026.
Amoxicillin starts killing bacteria within hours; per the NHS, you should feel better within a few days - fever and pain typically ease within 48 to 72 hours. Two rules around the timeline: finish the whole course even when you feel fine (early stopping breeds resistant bacteria), and space doses evenly. Two checkpoints: worse or no better after about 3 days - call the prescriber; still unwell after the course - that is not normal. A rash with hives or swelling during treatment can be allergy: stop and get urgent advice. Pymander is a free AI doctor, 24/7 by text, and can help you judge whether your recovery is on schedule.
What to do
- Judge at 48 to 72 hours: fever and pain should be easing by then.
- Finish the course: feeling fine is the medicine working, not permission to stop.
- Call if worse at 3 days: resistance or a wrong target needs a new plan.
- Stop and call for hives or swelling: penicillin allergy can appear on any course.
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