Amoxicillin

Key facts

• Amoxicillin (found alone as Amoxil, or combined with clavulanic acid as Augmentin) is a penicillin-type antibiotic that kills susceptible bacteria by weakening their cell walls.
• It's taken as capsules, tablets or liquid, usually two or three times a day; food doesn't affect how well it works.
• Never take amoxicillin if you're allergic to penicillin or other beta-lactam antibiotics: this can trigger a severe, sometimes life-threatening reaction.
• Finish the entire course even if you feel better after a few days. Stopping early lets surviving bacteria regrow and helps drive antibiotic resistance.

What Amoxicillin treats

Amoxicillin treats ear infections, sinusitis, tonsillitis and strep throat, chest infections, urinary tract infections, skin infections, and dental infections, and it's sometimes given before dental procedures to prevent infection. Combined with clavulanic acid (Augmentin), it also covers bacteria that would otherwise destroy amoxicillin before it can act. It works only on bacterial infections, not colds, flu or other viral illnesses.

How Amoxicillin works

Bacteria build a rigid wall around themselves to survive and divide. Amoxicillin blocks the enzymes bacteria use to construct that wall, so as they try to grow, the wall fails and the cell bursts. Human cells have no equivalent wall, which is why amoxicillin can target bacteria without directly damaging your own tissue.

Before you take it

• Do not take amoxicillin if you have ever had a serious allergic reaction, hives, swelling or breathing difficulty, to any penicillin or cephalosporin antibiotic.
• Tell your prescriber if you have glandular fever (mononucleosis); a widespread rash is common if amoxicillin is given during this illness.
• Amoxicillin can make some hormonal contraceptives less reliable; ask whether you need additional contraception during and after the course.
• Tell your prescriber about kidney problems or anticoagulant medicines, both may need your dose or monitoring adjusted.

Side effects

Nausea, diarrhoea, mild rash and oral or vaginal thrush are common.

Stop and seek urgent medical care for any of these:

• Hives, facial or throat swelling, or breathing difficulty.
• Severe blistering or peeling skin.
• Watery or bloody diarrhoea, which can signal a C. difficile infection.
• Unusual bruising, bleeding, or a persistent sore throat and fever.

Safety essentials

• If you're allergic to penicillin, do not take amoxicillin or any related antibiotic under any circumstances; make sure this allergy is recorded wherever you receive care.
• Always finish the full prescribed course, even once you feel well, to clear the infection completely and reduce the spread of antibiotic-resistant bacteria.
• Only take antibiotics prescribed for you. Sharing tablets or saving leftover doses for a future illness is unsafe and encourages resistance.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.