Quick answer: Augmentin is amoxicillin plus a second ingredient called clavulanate (clavulanic acid). Clavulanate does not kill bacteria on its own. Its job is to disable the enzyme, beta-lactamase, that some bacteria use to destroy amoxicillin. That makes Augmentin effective against a wider range of bacteria, but it also brings more stomach upset and a small added risk of liver problems. Plain amoxicillin remains the better choice when the infection is one it can handle by itself.
This article is educational. Which antibiotic you need depends on the infection, local resistance patterns, your allergy history, and your health, so the decision belongs to your prescriber.
What this comparison covers
- Amoxicillin vs Augmentin at a glance
- The problem clavulanate solves
- How a prescriber decides: five questions
- Infection by infection: which one is typically used
- Side effects: what clavulanate adds
- The liver question
- How to take each one
- Strengths and formulations
- Penicillin allergy applies to both
- Why “stronger” is not always better
- Cost and availability
- Frequently asked questions
Amoxicillin vs Augmentin at a glance
| Feature | Amoxicillin | Augmentin (amoxicillin-clavulanate) |
|---|---|---|
| Active ingredients | Amoxicillin | Amoxicillin + clavulanate |
| Drug class | Aminopenicillin | Aminopenicillin + beta-lactamase inhibitor |
| Spectrum | Narrower | Broader (covers beta-lactamase-producing bacteria) |
| Typical use | Strep throat, many ear infections, some sinus, dental, and chest infections | Infections likely to involve resistant or mixed bacteria, such as bites, some sinus, ear, skin, and urinary infections |
| Diarrhea / stomach upset | Common but usually mild | More frequent |
| Liver injury risk | Rare | Rare, but higher than with amoxicillin alone |
| Take with food? | Optional | Recommended, at the start of a meal |
| Allergy cross-reactivity | Penicillin allergy applies | Penicillin allergy applies |
| Relative cost | Lower | Typically higher |
The problem clavulanate solves
To see why two versions exist, picture how amoxicillin works. It interferes with the building blocks of the bacterial cell wall, causing the bacterium to weaken and burst. Many bacteria have learned to fight back by producing an enzyme called beta-lactamase. This enzyme slices through the chemical ring at the heart of penicillins, including amoxicillin, and renders them harmless before they can act.
Two common respiratory bacteria, Haemophilus influenzae and Moraxella catarrhalis, are well known for producing beta-lactamase in a large share of cases. So is Staphylococcus aureus that is not methicillin-resistant, along with several gut and anaerobic organisms. Against such bacteria, plain amoxicillin can fail.
Clavulanate acts like a decoy. It binds to beta-lactamase and ties it up, so the amoxicillin partner can do its job. Think of clavulanate as a bodyguard that distracts the enzyme while amoxicillin gets to the target.
What clavulanate does not do is just as important:
- It does not make amoxicillin effective against MRSA (methicillin-resistant Staph aureus).
- It does not cover Pseudomonas.
- It does not cover “atypical” organisms like Mycoplasma or Chlamydophila, which are the cause of some pneumonias.
- It does not help against viruses. Colds, flu, and most sore throats and bronchitis will not respond to either medicine.
How a prescriber decides: five questions
Rather than thinking of Augmentin as “amoxicillin but stronger,” it helps to see how clinicians reason through the choice. They typically ask five questions, and you can use them to understand your own prescription.
1. Is the likely culprit sensitive to plain amoxicillin?
If the infection is probably caused by an organism that does not make beta-lactamase, such as group A strep (see amoxicillin for strep throat), plain amoxicillin is the better match. Adding clavulanate gives no extra benefit and only adds side effects.
2. Could beta-lactamase producers be involved?
If the infection is one where those organisms are common, clavulanate has a real purpose. Examples include sinus infections that follow recent antibiotic use, ear infections that have not responded to amoxicillin, and animal or human bite wounds.
3. Has the patient taken amoxicillin recently?
Prior antibiotic exposure in the last month or so increases the chance of resistant bacteria. Guidelines for children’s ear infections, for instance, commonly suggest switching to amoxicillin-clavulanate when amoxicillin was used recently or when a pink-eye syndrome accompanies the ear infection.
4. Is the infection polymicrobial?
Bites, dental abscesses, certain abdominal and skin infections, and diabetic foot infections frequently involve a mix of aerobic and anaerobic bacteria. Augmentin’s wider reach is helpful there.
5. Is there a reason to avoid clavulanate?
Past liver problems linked to Augmentin, existing liver disease, or particularly poor tolerance of gastrointestinal side effects might lead a prescriber to avoid the combination.
Behind all of this sits a principle that infectious-disease doctors repeat: use the narrowest antibiotic that will reliably work. Narrower drugs spare more of your healthy bacteria and are less likely to drive resistance.
Infection by infection: which one is typically used
These patterns reflect common clinical guidance, but they are not rules. Local resistance rates, patient age, severity, and allergies all change the answer. Always follow your own prescriber’s plan.
Strep throat
Typically amoxicillin (or penicillin V). Group A strep does not produce beta-lactamase and remains very sensitive. Augmentin is rarely appropriate.
Ear infections (acute otitis media) in children
Often high-dose amoxicillin first, and amoxicillin-clavulanate in specific situations. Those situations include recent amoxicillin use, ear infection together with purulent conjunctivitis, or treatment failure after 48 to 72 hours. Some children’s ear infections are managed with watchful waiting, as per pediatric guidance.
Sinus infections (acute bacterial sinusitis)
Depends on age and guideline. Many sinus infections are viral and resolve without antibiotics. When antibiotics are justified, guidelines for adults often prefer amoxicillin-clavulanate because of beta-lactamase-producing organisms, while pediatric guidance allows amoxicillin with or without clavulanate depending on risk factors such as daycare attendance, recent antibiotic exposure, or severe illness.
Community-acquired pneumonia
High-dose amoxicillin is a common first choice for otherwise healthy outpatients, sometimes combined with another antibiotic. Amoxicillin-clavulanate may be used for those with other medical conditions or recent antibiotic exposure, usually together with a drug that covers atypical bacteria.
Bites (animal and human)
Typically amoxicillin-clavulanate. Mouth bacteria from cats, dogs, and people include organisms that require both aerobic and anaerobic coverage. Plain amoxicillin is often inadequate.
Skin and soft tissue infections
It depends on the likely bacteria. Many simple skin infections are caused by strep or MSSA. Amoxicillin-clavulanate may be used for mixed or bite-related infections, while other agents are chosen when MRSA is suspected.
Dental infections
Amoxicillin is a common choice, and Augmentin may be selected for more severe, spreading, or recurrent infections. Antibiotics are an addition to dental treatment, not a replacement for it.
Urinary tract infections
Not usually the first choice. Because many gut bacteria that cause UTIs, particularly E. coli, are resistant to amoxicillin, other antibiotics are usually preferred. Amoxicillin-clavulanate may be used in specific situations based on culture results.
Lyme disease and certain other infections
Amoxicillin is one of the options for early Lyme disease in some people, notably children and pregnant women. Clavulanate is not needed for that purpose.
Helicobacter pylori (stomach ulcer bacteria)
Amoxicillin is a component of several combination regimens. Augmentin is generally not used for this.
| Infection | Often starts with | Augmentin more likely when |
|---|---|---|
| Strep throat | Amoxicillin | Rarely needed |
| Ear infection | Amoxicillin | Recent amoxicillin use, conjunctivitis, or no improvement |
| Sinusitis | Amoxicillin or amoxicillin-clavulanate (guideline-dependent) | Adults, resistance risk, severe illness |
| Pneumonia | High-dose amoxicillin (healthy outpatients) | Other illnesses or recent antibiotics |
| Bite wounds | Amoxicillin-clavulanate | Almost always |
| Dental infection | Amoxicillin | Severe or spreading cases |
| UTI | Other antibiotics preferred | Culture-guided situations |
Side effects: what clavulanate adds
The shared side effects of the two drugs are the usual penicillin ones: nausea, vomiting, diarrhea, rash, and, rarely, allergic reactions. A full list with warning signs is in our amoxicillin side effects guide.
The difference is one of degree. Studies and prescribing information consistently show that diarrhea and other digestive complaints are more common with amoxicillin-clavulanate than with amoxicillin alone, and the clavulanate component is generally thought to drive that extra gut upset. Clavulanate seems to stimulate gut motility and irritate the digestive lining.
Augmentin-related issues worth knowing include:
- Diarrhea that can be significant, particularly with higher-dose formulations
- Nausea and vomiting, improved by taking the tablet at the start of a meal
- Diaper rash and oral or vaginal thrush, related to gut and skin flora changes
- Abnormal liver blood tests and, rarely, jaundice (see next section)
If Augmentin upset your stomach badly in the past, say so. Plain amoxicillin may be an option if the infection allows it. Conversely, if amoxicillin did not work, it does not mean Augmentin will always fix the issue, since the problem could be something other than beta-lactamase.
The liver question
Amoxicillin-clavulanate is among the better-known causes of drug-induced liver injury, simply because it is prescribed so widely. The numbers are small in absolute terms, but the pattern is worth understanding:
- It usually looks like cholestatic hepatitis, a build-up of bile that causes yellow skin or eyes, dark urine, pale stools, itching, and fatigue.
- It often appears after treatment ends, sometimes a week or more later, which surprises people.
- Risk factors reported in studies include older age, male sex, longer or repeated courses, and previous episodes of Augmentin-related liver trouble.
- Most cases recover after stopping the drug, though recovery can be slow and rare cases are severe.
Call your prescriber if you notice yellowing, dark urine, pale stool, itching all over, or unexplained severe tiredness, even after the course is finished. This is another reason to avoid drinking heavily during and after treatment, and to read our alcohol and amoxicillin guide if you are weighing a drink.
Pure amoxicillin has a much lower reported rate of liver injury, which is one more reason clinicians prefer it when it is adequate.
How to take each one
Amoxicillin
- Capsules, tablets, chewables, and liquid suspension are available.
- May be taken with or without food.
- Doses are spaced evenly through the day, or given once or twice daily depending on the regimen.
- Shake liquid suspension well and measure using the supplied device.
Augmentin
- Take at the start of a meal. This reduces stomach upset and helps the clavulanate be absorbed better.
- Do not crush or split extended-release tablets.
- Never swap tablet strengths or formulations casually. Because the amounts of clavulanate differ, two tablets of one strength are not equal to one tablet of another, and too much clavulanate in a day increases diarrhea risk.
- Refrigerate liquid suspension if the label says so, and discard it after the stated number of days.
For both, finish the course unless your clinician instructs otherwise. If you are unsure how quickly the medicine leaves your body or how that affects timing, our article on how long amoxicillin stays in your system answers that.
Strengths and formulations
Augmentin products are labeled with two numbers, such as 500/125. The first is the amount of amoxicillin; the second is the amount of clavulanate in milligrams. Common labels include:
- 250/125 and 500/125 tablets
- 875/125 tablets
- Chewable tablets and powder for suspension in different ratios for children
- ES-600 suspension, which uses a higher amoxicillin-to-clavulanate ratio for high-dose pediatric treatment
- XR (extended-release) tablets for certain adult infections
The ratio matters. Pediatric high-dose products use a different ratio so that children can get a high amoxicillin dose without a large clavulanate dose, which would otherwise worsen diarrhea.
Plain amoxicillin comes as 250 mg and 500 mg capsules, 500 mg and 875 mg tablets, chewables, and liquid. As we explain in the side effects article, the strength does not change the type of side effects.
“Augmentin” is the original brand name, and generic amoxicillin-clavulanate is widely available and considered equivalent when it meets regulatory standards.
Penicillin allergy applies to both
If you are allergic to penicillin, you should not take either one without your prescriber’s explicit clearance. Both contain amoxicillin, and amoxicillin is a penicillin. Tell every clinician about past reactions, and describe them as precisely as you can: hives, swelling, breathing trouble, or a flat rash days later. That information shapes the decision, and an allergist can sometimes test whether the label is still accurate.
Also tell your prescriber if you have previously had jaundice or liver problems after taking Augmentin, since that is a reason to avoid it in the future.
Why “stronger” is not always better
It is tempting to assume a broader antibiotic is a safer bet. Consider the costs:
- More collateral damage. Broad-spectrum drugs disrupt more of your normal gut bacteria, which is linked to diarrhea and increased risk of C. difficile infection.
- More resistance pressure. Each unnecessary use of a broad drug adds to the resistance problem at the individual and community level. The CDC’s antibiotic stewardship information explains why prescribers aim to match drug to bug.
- More side effects for no gain. If plain amoxicillin kills the bacteria involved, the clavulanate adds risk without benefit.
The same principle shows up across medicine, from antibiotics to anti-parasitic drugs. If you enjoy seeing how a single treatment decision depends on the target, our comparison of albendazole vs mebendazole follows a similar logic.
Cost and availability
Both are available as inexpensive generics in most places, but amoxicillin is typically the cheaper of the two, sometimes by a notable margin. Pharmacies in the United States often include generic amoxicillin on low-cost discount lists. Augmentin brand and some formulations, particularly extended-release or high-dose pediatric suspensions, can cost more. Coverage rules differ by insurer, so ask your pharmacist for the generic price.
Supply shortages of liquid amoxicillin have occurred in recent years. If a pharmacy cannot fill a pediatric suspension, ask your prescriber about alternatives rather than splitting adult tablets without guidance.
Four real-world scenarios
Abstract rules are easier to remember when you see them applied. These are simplified, fictional examples, not recommendations for any individual.
Scenario 1: A teenager with a confirmed strep test
A rapid test is positive, there is no allergy history, and the teen has not taken antibiotics recently. Strep does not make beta-lactamase, so plain amoxicillin (or penicillin V) fits. Prescribing Augmentin would add diarrhea risk without improving the odds of cure.
Scenario 2: A toddler whose ear infection did not improve
The child has been on amoxicillin for three days with persistent fever and ear pain. A clinician re-examines the ear and may switch to amoxicillin-clavulanate, because beta-lactamase-producing H. influenzae or Moraxella could be responsible. The switch is made by the clinician after a re-check, not at home.
Scenario 3: A cat bite on the hand
Cat bites push bacteria deep into tissue, and mouth flora includes organisms that need mixed coverage. Amoxicillin-clavulanate is the usual choice, and the wound itself also needs proper cleaning and medical assessment. This is a case where “broader” is justified.
Scenario 4: An adult with a long, severe sinus infection
Symptoms have lasted more than ten days without improving, or have worsened after initial improvement. If a clinician decides antibiotics are warranted, amoxicillin-clavulanate is often selected for adults, because resistant organisms are more likely. Saline rinses and pain relief remain part of the plan.
Common myths about amoxicillin and Augmentin
- Myth: Augmentin is a “better” antibiotic. It is a different tool. For strep throat or uncomplicated infections caused by sensitive bacteria, amoxicillin works as well with fewer side effects.
- Myth: If amoxicillin failed, I need Augmentin. Not necessarily. The illness may be viral, the dose may have been missed, or a different drug class may be needed. A re-evaluation is the right step.
- Myth: Clavulanate is an antibiotic. On its own it has only weak antibacterial activity. Its main role is protecting amoxicillin from enzymes.
- Myth: Taking it longer makes it work better. Longer courses than needed raise side-effect and resistance risks. Duration is chosen for each infection.
- Myth: Generic versions are weaker. Generic products must meet regulatory standards for the same active ingredients, strength, and performance.
Five questions to ask your pharmacist
- “Is this plain amoxicillin or amoxicillin with clavulanate?” Check the label for two numbers, such as 875/125.
- “Should I take this with food, and at what point in the meal?”
- “What should I do if I miss a dose or vomit after taking it?”
- “Does this interact with my other medicines or supplements?” This matters particularly for blood thinners, methotrexate, and gout treatments.
- “Which symptoms mean I should call you or my doctor before the course is finished?”
Writing the answers on the pharmacy bag or in your phone helps if you need to call later.
Frequently asked questions
Is Augmentin stronger than amoxicillin?
It is broader, not necessarily stronger. Amoxicillin in both products is the same drug. Clavulanate extends the range of bacteria it can attack by neutralizing beta-lactamase.
Can I switch from amoxicillin to Augmentin on my own?
No. Switching should come from a clinician who knows the infection and your history. If you are not improving after about 48 to 72 hours, call your prescriber instead of changing medicines yourself.
Which is better for a sinus infection?
It depends on guidelines, age, and risk factors. Adults are often given amoxicillin-clavulanate, whereas some children can start with amoxicillin. Many sinus infections are viral and need no antibiotic at all.
Which is better for strep throat?
Plain amoxicillin or penicillin. Augmentin is not needed and causes more digestive upset.
Does Augmentin cause more diarrhea than amoxicillin?
Generally yes. Clavulanate is considered the main reason. Taking Augmentin at the start of a meal can help.
Why is Augmentin taken with food?
Food at the start of a meal reduces nausea and helps absorption of clavulanate.
Can children take Augmentin?
Yes, in age- and weight-appropriate pediatric formulations. Never use adult tablets for a child without guidance, since the amoxicillin-to-clavulanate ratio and total dose matter.
Is Augmentin safe in pregnancy or breastfeeding?
Amoxicillin-clavulanate is commonly used in pregnancy when needed, and amoxicillin is generally considered compatible with breastfeeding, but your obstetric provider should confirm the choice for you.
Can I drink alcohol on Augmentin or amoxicillin?
There is no direct interaction, but alcohol can worsen stomach upset and dehydration, and heavy drinking is unwise when liver effects are possible. See our full guide, can you drink alcohol on amoxicillin.
What if neither works?
Infections that do not respond may be viral, caused by resistant bacteria, or need drainage or a different antibiotic. Your clinician may order a culture and choose a drug based on results.
Key takeaways
- Augmentin = amoxicillin + clavulanate. Clavulanate blocks beta-lactamase, extending amoxicillin’s reach.
- Use the narrowest antibiotic that works: amoxicillin for strep, many ear infections, and other sensitive bacteria; Augmentin for bites and infections where beta-lactamase producers are likely.
- Augmentin causes more diarrhea and carries a small added risk of liver injury, sometimes after the course ends.
- Take Augmentin at the start of a meal. Amoxicillin works with or without food.
- Both are penicillins, so a penicillin allergy affects both.
- Never switch or stretch antibiotics on your own.
Medical disclaimer: This article provides general information and does not replace professional medical advice. Antibiotic selection depends on the individual. Follow your prescriber’s instructions and seek urgent care for signs of a serious reaction such as swelling, trouble breathing, widespread blistering rash, or severe diarrhea.
