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
Common questions
How long does amoxicillin take to work?
The NHS answer: amoxicillin begins killing bacteria within hours of the first dose, and for most infections you should feel better within a few days, typically 1 to 3 days depending on what is being treated. The usual course length runs 5 to 14 days. What improvement looks like: fever and pain usually ease first (often within 48 hours for strep throat and ear infections, the two most common reasons people take it), then energy returns, then the remaining symptoms clear. The rules that matter: take it at evenly spaced times (two or three times daily depending on the prescription) so blood levels stay steady, with or without food as you prefer since amoxicillin does not care, and finish every last pill, because the NHS is explicit that stopping early lets the infection return and encourages resistant bacteria. The warning signs while on it: a rash can be a true allergy (hives, swelling, wheeze mean stop and seek care now) or the harmless amoxicillin rash common with mono (flat, not itchy, but still worth a call). The checkpoint: no improvement by day 3, or worsening at any point, means call the prescriber, since the bacteria may be resistant or the diagnosis may be off. And a useful preventive: yeast overgrowth is a common amoxicillin side effect, so probiotic-rich food during the course is a reasonable habit.