How long does amoxicillin take to work?
Last updated September 3, 2026.
Amoxicillin starts killing bacteria within hours, and most people feel better within 1 to 3 days; the NHS guidance is "a few days" for most infections. Courses typically run 5 to 14 days. Improvement order: fever and pain ease first, often within 48 hours for strep and ear infections, then energy, then residual symptoms. The practical rules: dose at evenly spaced times to keep levels steady, take it with or without food (it absorbs either way), and finish every pill, because stopping early invites recurrence and resistance. The watch-fors: hives, facial swelling, or wheeze are an allergy emergency; a flat non-itchy rash (common if the underlying illness is actually mono) still merits a call. Checkpoint: no improvement by day 3 or any worsening means contact the prescriber, because the bacteria may be resistant or the diagnosis wrong. Bonus habit: probiotic-rich food during the course, since yeast overgrowth is a common side effect.
What to do
- Working within hours, feeling better in 1 to 3 days.
- Evenly spaced doses, with or without food.
- Finish every pill: early stops breed resistance.
- Hives or swelling: emergency; flat rash: call.
- Day 3, no improvement: call the prescriber.
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