Amoxicillin: uses, dosage and how to take this antibiotic correctly

Amoxicillin is one of the most widely used antibiotics in the world — a penicillin that treats a broad range of bacterial infections. This guide covers what it treats, the usual dosage, how to take it correctly, and the antibiotic-stewardship rules that matter for everyone. We stock amoxicillin in 250mg, 500mg, 650mg and 1000mg.

What amoxicillin treats

Amoxicillin treats bacterial infections — commonly chest infections and pneumonia, ear infections, sinus and throat infections, dental abscesses, and some urinary and skin infections. It works by stopping bacteria from building their cell walls, killing them. Crucially, it works only on bacteria, not viruses — so it does nothing for colds, flu or most sore throats, which are usually viral. Using it for viral illness is both useless and harmful (see resistance below).

Typical dosage

A common adult dose is 250mg to 500mg three times a day, though it varies by infection — some infections use higher doses or twice-daily regimens, and dental or specific infections have their own schedules. Children are dosed by weight. The key is to take it at evenly spaced intervals (e.g. every 8 hours) to keep a steady level in the blood, and to take exactly what's prescribed for your infection.

How to take it correctly

You can take amoxicillin with or without food. Take it at regular intervals, and — most importantly — finish the entire course, even if you feel better after a few days. Stopping early leaves the hardiest bacteria alive, which is how infections come back stronger and how resistance develops. If you miss a dose, take it when you remember (unless it's nearly time for the next one — never double up).

Side effects

Common effects are nausea, diarrhoea and a mild rash. Diarrhoea happens because antibiotics disturb gut bacteria; a probiotic can help, but severe or bloody diarrhoea needs medical attention. A penicillin allergy is important: if you've ever had hives, swelling or breathing difficulty with penicillin, you must not take amoxicillin — tell any prescriber. A widespread rash, especially with swelling or breathlessness, needs urgent care.

Antibiotic resistance — why the rules matter

Antibiotic resistance is one of the biggest threats in medicine, and it's driven by misuse: taking antibiotics for viral illness, not finishing courses, or using leftover tablets. Every unnecessary or incomplete course helps bacteria evolve resistance, making future infections harder to treat for everyone. Use amoxicillin only for a genuine bacterial infection, at the right dose, for the full course — see the bacterial-infections guide.

Key points to remember

• What amoxicillin treats: Amoxicillin treats bacterial infections — commonly chest infections and pneumonia, ear infections, sinus and throat infections, dental abscesses, and some urinary and skin infections. It works by stopping bacteria from building their cell walls, killing them.
• Typical dosage: A common adult dose is 250mg to 500mg three times a day, though it varies by infection — some infections use higher doses or twice-daily regimens, and dental or specific infections have their own schedules. Children are dosed by weight.
• How to take it correctly: You can take amoxicillin with or without food. Take it at regular intervals, and — most importantly — finish the entire course, even if you feel better after a few days.
• Side effects: Common effects are nausea, diarrhoea and a mild rash. Diarrhoea happens because antibiotics disturb gut bacteria; a probiotic can help, but severe or bloody diarrhoea needs medical attention.
• Antibiotic resistance — why the rules matter: Antibiotic resistance is one of the biggest threats in medicine, and it's driven by misuse: taking antibiotics for viral illness, not finishing courses, or using leftover tablets. Every unnecessary or incomplete course helps bacteria evolve resistance, making future infections harder to treat for everyone.

Common questions

What is amoxicillin used for?

Bacterial infections — chest, ear, sinus, throat, dental, and some urinary and skin infections. It works only on bacteria, not viruses, so it doesn't help colds or flu.

What is the usual dose of amoxicillin?

Commonly 250–500mg three times a day for adults, though it varies by infection. Take it at evenly spaced intervals and always finish the full prescribed course.

Can I take amoxicillin with food?

Yes — with or without food. Take it at regular intervals to keep a steady level, and complete the whole course even if you feel better.

What if I'm allergic to penicillin?

Do not take amoxicillin — it's a penicillin. If you've had hives, swelling or breathing difficulty with penicillin before, tell any prescriber so an alternative can be used.

References & further reading

• NHS: Sildenafil (Viagra) — uses, dosage, side effects — official UK guidance on the active ingredient.
• Goldstein I, et al. NEJM 1998 — the pivotal sildenafil trial — lead-authored by Dr. Irwin Goldstein (San Diego Sexual Medicine).
• Phosphodiesterase 5 Inhibitors — StatPearls, NCBI Bookshelf — clinical pharmacology reference.

This article is general information, not medical advice. Always consult a healthcare professional before starting any medication.