Amoxicillin is a prescription penicillin antibiotic used to treat infections caused by susceptible bacteria. It is usually taken by mouth as capsules or liquid; injectable formulations are generally used in hospital. It does not treat viral infections.
Aminopenicillin beta-lactam antibiotic.
Prescription-only; available as oral capsules and liquids, with injections mainly used in hospital.
It can be taken before or after food because food does not materially reduce absorption.
Many people begin to feel better within a few days. Seek review if symptoms worsen or have not begun to improve after 3–5 days.
Diarrhoea, nausea and skin rash.
Licensed indications vary by product. Amoxicillin should be chosen according to the infection site and severity, the likely organism, local susceptibility and antimicrobial policy.
Selected respiratory, ear, nose and throat infections, including acute bacterial sinusitis, acute otitis media, streptococcal tonsillitis or pharyngitis, exacerbations of chronic bronchitis and community-acquired pneumonia.
Selected urinary infections, including acute cystitis, asymptomatic bacteriuria in pregnancy and acute pyelonephritis.
Dental abscess with spreading cellulitis.
Typhoid or paratyphoid fever and Lyme disease.
Helicobacter pylori eradication as one part of a combination regimen.
Selected specialist uses, including prosthetic joint infection and endocarditis prophylaxis.
Amoxicillin binds bacterial penicillin-binding proteins and interrupts construction of peptidoglycan, an essential part of the cell wall. The weakened wall breaks down and susceptible bacteria die. Resistance can occur when bacteria produce beta-lactamases, alter the target proteins, reduce drug entry or increase efflux.
Dose and duration vary substantially with the infection, likely susceptibility, severity, route, age, weight and kidney function. Follow the individual prescription. These examples come from a current UK 500 mg capsule SmPC and are not universal prescribing instructions; children, people with renal impairment and users of other formulations may need different regimens.
250–500 mg every 8 hours, or 750 mg–1 g every 12 hours; severe infection may require 750 mg–1 g every 8 hours.
Determined by the infection and clinical response and generally kept as short as is effective.
500 mg–1 g every 8 hours.
Individualised according to the infection and response.
750 mg–1 g twice daily, combined with a proton-pump inhibitor and another appropriate antibiotic.
7 days in the cited capsule SmPC.
Take amoxicillin exactly as shown on the dispensing label and space doses as evenly as practical. Complete the prescribed course unless a clinician tells you to stop or change it; stop and seek help for a serious reaction.
Swallow capsules whole with water rather than opening, chewing or breaking them.
Amoxicillin may be taken before or after food.
Measure liquid with the supplied oral syringe or medicine spoon, not a kitchen teaspoon.
Check the liquid concentration and storage instructions because products are not interchangeable volume for volume.
Contact the prescriber if symptoms worsen or have not started to improve after 3–5 days.
Amoxicillin can be used during pregnancy when recommended by a clinician. Current UK pregnancy information does not identify concern that penicillin antibiotics harm the baby, and adequately treating infection is important for both mother and pregnancy. Exposure alone does not normally require extra monitoring for major birth defects beyond routine antenatal care.
Amoxicillin is generally compatible with breastfeeding a healthy, full-term infant because only very small quantities enter milk. Monitor the baby for diarrhoea, vomiting, poor feeding, oral thrush, rash, breathing problems or unusual sleepiness. Obtain specialist advice for a premature or unwell infant, prolonged treatment or complex maternal medication.
This is not an exhaustive interaction list. Tell the prescriber or pharmacist about prescribed medicines, over-the-counter products, vitamins and supplements.
Reduces renal tubular secretion of amoxicillin and can produce higher, more prolonged concentrations; concurrent use is not recommended in the cited SmPC.
Concurrent treatment may increase the likelihood of an allergic skin reaction.
Increased INR has been reported. Monitor coagulation when amoxicillin is started or stopped and adjust anticoagulant treatment if clinically required.
Penicillins may reduce methotrexate excretion and increase the risk of toxicity.
May interfere with amoxicillin’s bactericidal activity; consider the clinical relevance before combining treatment.
Evidence is insufficient to establish that combinations are safe, so disclose all products to the pharmacist or prescriber.
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For many infections, improvement begins within a few days. Contact the prescriber if symptoms worsen at any point or have not begun to improve after 3–5 days.
Yes. It can be taken before or after food. Taking it after a snack or meal may be more comfortable if it causes nausea.
Take it when remembered unless the next dose is nearly due. In that situation, omit the missed dose and continue normally. Do not double the dose.
There is no specific prohibition on alcohol with amoxicillin. Avoid it if it worsens nausea or you feel unwell, and follow any separate advice for your condition or other medicines.
Do not take it without urgent clarification from the prescriber. A confirmed allergy to amoxicillin or another penicillin is a contraindication, and a previous severe immediate reaction to another beta-lactam may also rule it out.
It can be used in pregnancy when recommended by a clinician. Current UK information does not identify concern that penicillin antibiotics harm the baby, while leaving an infection untreated can itself be harmful.
Usually yes for a healthy, full-term baby. Only small quantities enter milk, but monitor for diarrhoea, vomiting, thrush, rash, breathing problems, poor feeding or unusual drowsiness and seek advice if these occur.
Amoxicillin itself does not reduce contraceptive effectiveness. Vomiting, severe watery diarrhoea or diarrhoea lasting more than 24 hours can prevent an oral pill being absorbed properly, so follow the illness or missed-pill guidance supplied with the contraceptive.
Yes. Antibiotics can disturb normal microbial flora and allow Candida to overgrow. Ask a pharmacist or doctor for advice if oral or genital thrush develops.
The illness may not be bacterial, the organism may be resistant or produce beta-lactamase, the infection may need another treatment, or the diagnosis may be different. Do not increase or switch antibiotics yourself; seek review if symptoms worsen or fail to improve.
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.