Augmentin: what it is used for, dosage and side effects

What Augmentin is and which active substances it contains

Augmentin contains amoxicillin, an antibiotic from the penicillin group, together with clavulanic acid. In the Maltese register of medicines the entry Augmentin is recorded with amoxicillin and clavulanic acid as its active substances and the oral route of administration; the register also carries Augmentin Duo in a mixed fruit flavour, again by mouth, which is the kind of form intended for patients who cannot swallow tablets.

The second substance is not a second antibiotic. Clavulanic acid has almost no antibacterial effect of its own; it blocks bacterial enzymes called beta-lactamases, which some bacteria use to destroy amoxicillin before it can work. Adding it therefore restores activity against organisms that plain amoxicillin would no longer reach. This is why the combination is not simply a stronger version of amoxicillin but a different choice, made for a different reason.

The same pair of substances is marketed by several companies under their own names, and the medicine comes in more than one strength and more than one form. That makes the leaflet supplied with your own pack the document that matters, and it is worth reading even if you have taken an antibiotic with a similar name before. Authorised products in Malta and their product information are listed by the Medicines Authority.

What it is used for

Augmentin is used for infections caused by bacteria, and the decision to use it rests on what the doctor judges to be the likely organism and the site of the infection. Whether an antibiotic is needed at all, and whether this particular one is the right choice, is a clinical judgement that takes in examination findings, the course of the illness, other conditions and previous antibiotic treatment.

It does nothing at all against viruses. Most sore throats, colds and coughs are viral, which is why they do not get better faster with an antibiotic and why taking one anyway carries only the risks and none of the benefit. Fever by itself does not tell you which of the two you have, and neither does the colour of what you cough up; this is one of the reasons an examination is not a formality.

A course that is started should be completed as the doctor prescribed, and left-over antibiotics from a previous illness should not be used for a new one. Every unnecessary course pushes bacteria towards resistance, and resistance is not an abstract worry: it is the reason why some infections that were once easy to treat now need a different, less convenient medicine.

How the two substances work

Amoxicillin interferes with the building of the bacterial cell wall. Without an intact wall the bacterium cannot hold its shape against the pressure inside it, so it breaks down. Human cells have no such wall, which is why this family of antibiotics can be used at doses that kill bacteria without a corresponding effect on our own cells.

Some bacteria defend themselves by producing beta-lactamases, enzymes that split the chemical ring amoxicillin depends on. Clavulanic acid binds to those enzymes and takes them out of action, so the amoxicillin in the same tablet survives long enough to do its work. The two substances are therefore given together in fixed proportion, and that proportion differs between forms, which is another reason not to treat one pack as equivalent to another.

The medicine acts on bacteria wherever it reaches them, and that includes the harmless bacteria that normally live in the bowel. Disturbing that population is the reason why loose stools are among the commonest complaints during treatment, and why an antibiotic occasionally leads to a bowel infection that needs treatment of its own.

How it is taken and what to watch for

The dose, the interval between doses and the length of the course are set by the doctor and written in the leaflet supplied with your pack; they depend on the form, on the infection and, in children, on body weight. A suspension is measured with the measuring device supplied with it, not with a kitchen spoon, and the pack should be checked for its storage instructions, because some forms are kept refrigerated after they are made up.

The medicine is not used where there is hypersensitivity to penicillins or to any of the excipients in the pack, or where a previous course of this combination was followed by jaundice or a liver reaction. Those are contraindications, not reasons for extra care. Tell the doctor if you have ever had a rash, swelling or breathlessness after any penicillin, and do not assume that a reaction described to you as a childhood rash was harmless, because it changes which antibiotic can be used.

Particular care and a decision by the doctor are needed in kidney disease, in liver disease and where you are taking other medicines long term. Antibiotics can also interfere with some laboratory tests, so it is worth mentioning current treatment when blood or urine is being taken.

Do not stop a course early because you feel better and do not save the remaining tablets. If the illness does not improve as expected, or if it improves and then returns, that is information the doctor needs rather than a reason to start something else from the cupboard.

Interactions with other medicines

Allopurinol, used for gout, is associated with a higher chance of a skin rash when taken together with amoxicillin. Probenecid slows the removal of amoxicillin by the kidneys and is generally not combined with it. Both are the kind of long-term medicine a patient may not think of as relevant to a short antibiotic course, which is precisely why the doctor needs the full list.

With methotrexate the combination needs care, because antibiotics of this family can raise its level and its toxicity. With oral anticoagulants of the coumarin type, tests of clotting may change during and after a course, so the doctor may ask for them to be checked more often. These are not reasons to avoid treatment; they are reasons for it to be supervised.

Stomach upset and, in particular, vomiting or diarrhoea can reduce how much of any oral medicine is absorbed, and that includes hormonal contraception. If that happens during a course, look at the leaflet of the contraceptive for its own instructions and ask a pharmacist rather than guessing. List for the doctor and the pharmacist everything you take, including preparations bought without a prescription, food supplements and herbal products.

Side effects and when to seek help

The complaints described most often concern the digestive system: diarrhoea, nausea, loose stools and abdominal discomfort. Thrush of the mouth or the genital area is also common, because the medicine disturbs the balance of organisms that normally keep yeasts in check. Skin rash and itching are described as well.

Less often, headache, dizziness and changes in blood test results including liver enzymes are reported. Rare but serious events include severe allergic reactions, severe skin reactions with blistering or peeling, inflammation of the liver with jaundice, effects on the kidneys and a bowel infection with persistent, watery diarrhoea that can begin during treatment or after it has finished.

Seek medical help without delay if the face, lips or tongue swell, if breathing becomes difficult, if a widespread rash with blisters appears, if the skin or the whites of the eyes turn yellow, if the urine becomes dark, or if diarrhoea is severe, watery, bloody or accompanied by fever and abdominal pain. In a life-threatening situation call 112 or go to Accident and Emergency.

The complete list of side effects with information on how often each occurs is in the leaflet supplied with your pack. A suspected side effect can be reported to your doctor or pharmacist, and safety of medicines on the Maltese market is monitored by the Medicines Authority.

Why we do not issue a prescription for this medicine

An antibiotic is the one group where our model does not fit, and the reason is clinical rather than administrative. A new infection is a new clinical problem, not the continuation of treatment that someone has already assessed. Deciding whether an antibiotic is needed at all, and which one, depends on things a written questionnaire cannot supply: listening to the chest, looking at the throat, the ear or the skin, measuring temperature and, in part of cases, taking a swab or a urine sample. So we do not assess this medicine and we issue no document for it.

This is a deliberate limit and it is not one we would trade away. Handing out an antibiotic on the strength of typed answers would mean guessing at a diagnosis that has not been made, with two costs that fall on other people as well: a patient treated for the wrong thing loses the time in which the right treatment could have started, and every unnecessary course pushes bacteria further towards resistance.

What we do assess is established, long-term treatment that a doctor has already begun, and only for medicines outside the excluded groups. How that kind of review works, and what a doctor needs before repeating a treatment, is described at /online-doctor/ and at /blog/repeat-prescription-without-a-visit/.

If you already hold a prescription for Augmentin written by a doctor in another country of the European Union, that is a different question, and it is about the pharmacy rather than about us. What such a prescription has to carry and what a pharmacist in Malta looks at before dispensing is set out at /blog/eu-prescription-maltese-pharmacy/. For a suspected infection now, see a doctor who can examine you.