BMA Concise Guide to Medicine & Drugs


Brand name Amoxil

Used in the following combined preparations Augmentin, Co-amoxiclav


Drug group Penicillin antibiotic

Overdose danger rating Low

Dependence rating Low

Prescription needed Yes

Available as generic Yes


Amoxicillin is a penicillin antibiotic. It is prescribed to treat a variety of infections, but is particularly useful for treating ear, nose, and throat infections, respiratory tract infections, cystitis, uncomplicated gonorrhoea, and certain skin and soft tissue infections. Amoxicillin is sometimes combined with clavulanic acid (as co-amoxiclav) to prevent bacteria from breaking down amoxicillin; this makes it effective against a wider range of bacteria than amoxicillin alone. Doses of co-amoxiclav are given as two numbers (e.g. 500/125 is 500mg amoxicillin plus 125mg clavulanic acid).

Amoxicillin/co-amoxiclav can cause minor stomach upsets and a rash. It can also provoke a severe allergic reaction with fever, swelling of the mouth and tongue, itching, and breathing difficulties.


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, capsules, liquid, powder (dissolved in water), injection.

Frequency and timing of doses Normally 3 x daily.

Dosage range Adults 750mg–1.5g (of amoxicillin) daily. In some cases a short course of up to 6g (of amoxicillin) daily is given. A single dose of 3g (of amoxicillin) may be given as a preventative. However, dosage range depends on preparation and condition being treated. Children Reduced dose according to age and weight.

Onset of effect 1–2 hours.

Duration of action Up to 8 hours.

Diet advice Make sure you keep well hydrated.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. Take your next dose at the scheduled time.

Stopping the drug Take the full course. Even if you feel better, the original infection may still be present if treatment is stopped too soon.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.


The most common adverse effects are diarrhoea and nausea. You should talk to your doctor if these are severe or if you experience abdominal pain, unexplained bruising, or a sore throat or fever. If you develop a rash, itching, wheezing or breathing difficulties, or joint swelling, this may indicate an allergy to the drug. You should stop taking it and call your doctor immediately. Rarely, jaundice may occur, in some cases weeks or even months after finishing treatment. If you do develop jaundice, call your doctor immediately and stop taking the drug if you have not already done so.


Anticoagulant drugs Amoxicillin and co-amoxiclav may alter the anticoagulant effect of these drugs.

Allopurinol Amoxicillin may increase the likelihood of allergic skin reactions.

Oral contraceptives Amoxicillin and co-amoxiclav may reduce the effectiveness of the oral contraceptive pill.

Oral typhoid vaccine Amoxicillin and co-amoxiclav inactivate this vaccine. Avoid taking these drugs for 3 days before and after having the vaccine.


Be sure to tell your doctor if:

· You are allergic to penicillin antibiotics or cephalosporin antibiotics.

· You have glandular fever (infectious mononucleosis).

· You have a history of allergy.

· You have liver problems, or have had previous liver problems with amoxicillin/co-amoxiclav.

· You are taking other medicines.

Pregnancy No evidence of risk.

Breast-feeding No evidence of risk.

Infants and children Reduced dose necessary.

Over 60 No known problems.

Driving and hazardous work No known problems.

Alcohol No known problems.


Amoxicillin and co-amoxiclav are usually given only for short courses of treatment.