Short verdict on amoxicillin vs Augmentin: Augmentin is amoxicillin plus clavulanic acid, so it covers more bacteria, but plain amoxicillin is still the better pick when the likely germ doesn’t make a beta-lactamase enzyme, and it’s gentler on your gut.
Here’s the Augmentin vs amoxicillin spec sheet first, then the reasoning a prescriber works through. The figures come from the FDA prescribing information, U.S. guidelines, and peer-reviewed studies, and the sources are linked throughout.
| Feature | Amoxicillin | Augmentin (amoxicillin clavulanate) |
|---|---|---|
| Drug class | Aminopenicillin (beta-lactam antibiotic) | Aminopenicillin + beta-lactamase inhibitor |
| Active ingredients | Amoxicillin only | Amoxicillin + clavulanate potassium (clavulanic acid) |
| What clavulanate adds | Nothing (not present) | Blocks beta-lactamase enzymes that would destroy amoxicillin |
| Spectrum | Narrower: strep, many pneumococci, non-enzyme-producing strains | Broader: adds enzyme-producing H. influenzae, M. catarrhalis, MSSA, some E. coli and Klebsiella, mouth anaerobes |
| Common adult tablets | 250 mg and 500 mg capsules; 500 mg and 875 mg tablets | 250/125, 500/125, 875/125 mg tablets; XR 1,000/62.5 mg extended-release |
| Liquids and chewables | Several suspension and chewable strengths | 125/31.25, 200/28.5, 250/62.5, 400/57 per 5 mL; ES-600 (600/42.9 per 5 mL) for children |
| Typical dosing frequency | Every 8 or 12 hours | Every 8 or 12 hours (XR: two tablets every 12 hours) |
| Take with food? | With or without food | Label advises the start of a meal to aid absorption and limit stomach upset |
| Diarrhea | Not clearly higher than placebo in trial pooling | 9% in label trials; about 1 extra case per 10 people treated vs placebo |
| Liver warning | Liver injury is very uncommon | Label warning for hepatitis and cholestatic jaundice |
| Generic and cost | Generic; usually among the cheapest antibiotics | Generic widely available; usually costs somewhat more |
If you just want the big picture of what plain amoxicillin treats, our guide to the infections amoxicillin covers is a good starting point. This page sticks to the comparison.
The one ingredient that makes the difference
Augmentin and amoxicillin share the same antibiotic engine. Both rely on amoxicillin, which latches onto proteins bacteria use to build their cell walls. Without a solid wall, the bacterium bursts and dies.
The only thing Augmentin adds is clavulanic acid (listed on labels as clavulanate potassium). So what is clavulanic acid? It’s a beta-lactamase inhibitor. On its own it barely kills bacteria at all. Its whole job is to protect amoxicillin.
Beta-lactamase, in plain language
Think of amoxicillin as a key that jams the lock on a bacterium’s wall-building machinery. Some bacteria have learned to make a pair of scissors, an enzyme called beta-lactamase, that snips the key in half before it reaches the lock.
Clavulanic acid works like a decoy. The scissors grab onto clavulanate instead and get stuck, so amoxicillin slips past intact. MedlinePlus describes it the same way: clavulanate stops bacteria from breaking down amoxicillin.
Which bacteria carry the “scissors”
The FDA prescribing information for Augmentin lists every approved use as an infection caused by beta-lactamase-producing strains. The main ones:
- Haemophilus influenzae: a common cause of ear infections, sinusitis, and bronchitis flare-ups. Many strains make beta-lactamase.
- Moraxella catarrhalis: another ear and sinus germ. Most strains make the enzyme.
- Staphylococcus aureus (MSSA): the methicillin-susceptible kind that causes many skin infections. Most strains shrug off plain amoxicillin.
- E. coli and Klebsiella: gut bacteria behind many urinary and some skin infections.
- Mouth anaerobes: bacteria that thrive without oxygen, found in dental abscesses and bite wounds. Some of these produce beta-lactamase too.
Where clavulanate doesn’t help at all
Not every kind of resistance involves scissors. Some bacteria simply change the lock so the key no longer fits. Clavulanate can’t fix that, because there’s no enzyme to block.
- MRSA carries an altered wall-building protein (called PBP2a) that penicillin-type drugs barely bind. Augmentin is no better than amoxicillin here. Neither works.
- Penicillin-resistant pneumococcus (Streptococcus pneumoniae) gets its resistance from reshaped penicillin-binding proteins, not beta-lactamase. The fix is a higher dose of amoxicillin, which can still outmuscle the weakened lock. That’s why ear infection and pneumonia guidelines lean on high-dose amoxicillin rather than adding clavulanate.
The FDA label backs this up in its own way: its formulations aren’t indicated for pneumococci with penicillin MICs of 4 mcg/mL or higher, and it notes that ear infections caused by pneumococcus alone can be treated with amoxicillin.
Is Augmentin stronger than amoxicillin?
This is the most common question people ask when comparing amoxicillin vs Augmentin, and the honest answer is: broader, not stronger.
An 875 mg tablet of amoxicillin and an 875/125 mg tablet of Augmentin deliver the same amount of amoxicillin. Against a germ that doesn’t make beta-lactamase, like the strep bacteria behind strep throat, they kill at the same rate. The clavulanate is just along for the ride.
Where Augmentin pulls ahead is coverage. It reaches enzyme-producing bacteria that plain amoxicillin can’t. So the decision isn’t about “power.” It’s about which bacteria are likely to be causing your infection.
Why “broader” isn’t automatically better: Wider coverage means more of your normal gut bacteria get hit too. That’s the main reason Augmentin causes more diarrhea. It also adds more antibiotic pressure that drives resistance. The FDA label itself says not to use Augmentin when a culture shows the germ is susceptible to amoxicillin alone.
Say you have a sore throat and test positive for strep. Getting Augmentin “to be safe” adds side-effect risk with zero extra benefit, because group A strep doesn’t make beta-lactamase. Now say your dog bit your hand. Plain amoxicillin would leave some likely bacteria uncovered, so Augmentin is the better fit.
Infection-by-infection: which one is usually chosen
In real life, amoxicillin vs Augmentin is decided infection by infection. Clinicians pick between them by asking which germs are likely in that body site, and whether any of them make beta-lactamase. The table below summarizes typical U.S. practice for otherwise healthy people. Your own prescriber may choose differently based on allergies, local resistance, recent antibiotics, or other health conditions.
| Infection | Usual first choice | When the other one is used |
|---|---|---|
| Strep throat | Amoxicillin (or penicillin) | Augmentin isn’t a standard choice |
| Ear infection (child) | High-dose amoxicillin | Augmentin if amoxicillin in past 30 days, eye discharge (conjunctivitis), or treatment failure |
| Sinus infection | Amoxicillin or Augmentin (both listed first-line) | Augmentin favored by IDSA 2012; high-dose for risk factors |
| Animal or human bite | Augmentin | Plain amoxicillin not preferred |
| Tooth infection | Amoxicillin (or penicillin VK) | Augmentin if first-line drug isn’t working |
| Bladder infection (UTI) | Neither is first-line | Augmentin sometimes, guided by urine culture |
| COPD flare-up | Augmentin is one common option | Doxycycline or a macrolide are alternatives |
| Pneumonia (outpatient) | High-dose amoxicillin if otherwise healthy | Augmentin plus a second drug if chronic illness |
Strep throat: amoxicillin
Group A strep has never developed meaningful penicillin resistance. CDC’s adult outpatient prescribing summary lists amoxicillin or penicillin as first-line, typically for 10 days. Augmentin doesn’t add anything here. Our post on treating strep throat with amoxicillin covers testing, timing, and when you stop being contagious.
Ear infections: amoxicillin first, Augmentin as the backup
The American Academy of Pediatrics’ 2013 guideline on acute otitis media still shapes U.S. practice, and CDC’s pediatric outpatient summary (reviewed 2024) mirrors it. High-dose amoxicillin is first-line when antibiotics are needed. Amoxicillin-clavulanate is preferred instead when a child:
- Took amoxicillin in the past 30 days (resistant, enzyme-producing germs are more likely)
- Has pus-like eye discharge along with the ear infection, a combination often caused by H. influenzae
- Has a history of ear infections that didn’t respond to amoxicillin
If symptoms worsen or don’t improve within 48 to 72 hours on amoxicillin, the guideline suggests reassessing, and a switch to amoxicillin-clavulanate is a common next step. For kids with repeat infections, a prescriber may use the ES-600 suspension, which the label pairs with 90 mg/kg/day of amoxicillin split every 12 hours for 10 days. Our guide to amoxicillin for children’s ear infections walks through watchful waiting and what to expect day by day.
Sinus infections: often Augmentin, but either can be right
The 2012 IDSA guideline on acute bacterial rhinosinusitis recommended amoxicillin-clavulanate over plain amoxicillin for initial treatment. It rated that advice strong for children and weak for adults. The rationale: after pneumococcal vaccines became routine, enzyme-producing H. influenzae took up a bigger share of sinus infections.
The same guideline suggested high-dose amoxicillin-clavulanate (2 g twice daily for adults, or 90 mg/kg/day for children) when risks for resistant pneumococcus are present. Those risks include age under 2 or over 65, daycare attendance, recent hospitalization, antibiotics in the past month, a weakened immune system, or severe infection. It also shortened adult courses to 5 to 7 days.
More recent CDC summaries (reviewed 2024) list either amoxicillin or amoxicillin-clavulanate as first-line for adults and children. We found no newer IDSA sinusitis guideline replacing the 2012 version as of October 2026. Either way, most sinus infections are viral and clear without antibiotics, so many people shouldn’t get either drug.
Animal and human bites: Augmentin
Bite wounds are where Augmentin clearly wins. Dog and cat mouths carry Pasteurella; human mouths carry Eikenella. Both mix with staph, strep, and mouth anaerobes, several of which make beta-lactamase. Amoxicillin-clavulanate covers that whole mix in one pill, which is why it’s the standard oral choice for treating or preventing bite infections.
Cat bites, deep punctures, and bites on the hand, face, or genitals carry the highest infection risk. See a clinician the same day for any of those, and ask about tetanus and rabies too.
Tooth infections: amoxicillin first
The American Dental Association’s 2019 guideline, summarized in a CDC-hosted ADA chairside guide, starts with amoxicillin 500 mg three times daily (or penicillin VK) for 3 to 7 days, only when there are signs of spreading infection. If that doesn’t work, the ADA’s second step is either adding metronidazole or switching to amoxicillin-clavulanate 500/125 mg three times daily for 7 days.
The guideline’s bigger point: antibiotics don’t fix most toothaches. Draining the abscess, a root canal, or an extraction does. Read more in our post on using amoxicillin for a tooth infection.
Urinary tract infections: usually neither
For a simple bladder infection in a healthy, non-pregnant woman, CDC lists nitrofurantoin, trimethoprim-sulfamethoxazole (where local resistance is low), or fosfomycin as first-line. Plain amoxicillin is rarely a good guess because so many E. coli strains resist it. Augmentin is approved for UTIs caused by enzyme-producing E. coli, Klebsiella, and Enterobacter, and it’s sometimes used in pregnancy or once a urine culture shows the germ is susceptible.
COPD flare-ups: Augmentin is a common pick
When a COPD flare-up comes with thicker, discolored sputum, antibiotics can help. H. influenzae and M. catarrhalis are frequent culprits, and both often make beta-lactamase. That makes amoxicillin-clavulanate a sensible option alongside doxycycline or a macrolide, usually for about 5 days. Plain amoxicillin is a weaker fit here.
Community-acquired pneumonia: depends on your health
The 2019 ATS/IDSA pneumonia guideline splits outpatients into two groups. Healthy adults without major illnesses can take high-dose amoxicillin (1 g three times daily), since the main target is pneumococcus. Adults with conditions like chronic heart, lung, liver, or kidney disease, diabetes, alcohol use disorder, or no spleen get a broader start: amoxicillin-clavulanate (or a cephalosporin) plus a macrolide or doxycycline.
Macrolides come up a lot in these comparisons. If you’re weighing that path, our amoxicillin vs azithromycin comparison explains why azithromycin has lost ground for several respiratory infections.
Amoxicillin vs Augmentin side effects compared
Both drugs share the usual penicillin-family risks: rash, allergic reactions, yeast infections, and C. difficile diarrhea. Two differences stand out, though, and both trace back to clavulanate.
Augmentin side effects: diarrhea is the big one
Clavulanate irritates the gut more than amoxicillin does. A 2015 CMAJ systematic review of placebo-controlled trials by Gillies and colleagues found:
- Amoxicillin alone did not significantly raise diarrhea rates compared with placebo.
- Amoxicillin-clavulanate roughly tripled the odds of diarrhea. For about every 10 people treated, one extra person got diarrhea who otherwise wouldn’t have.
The Augmentin label reports diarrhea or loose stools in 9% of trial patients, nausea in 3%, and vomiting in 1%. Dosing schedule matters too. In the label’s pediatric ear infection trial, diarrhea hit 34% of children taking the older three-times-daily schedule versus 14% on twice-daily dosing. That’s why twice-daily dosing is now standard for kids. In adults, 875 mg twice daily and 500 mg three times daily caused similar overall diarrhea (15% vs 14%), but severe diarrhea or stopping because of it was less common on the twice-daily schedule (1% vs 2%).
Call your doctor if diarrhea is watery and frequent, bloody, or comes with cramps or fever. That can signal C. difficile infection, which can show up during treatment or even two months or more after you finish.
Liver injury: rare, but more linked to Augmentin
This is the difference most people haven’t heard about. NIH’s LiverTox entry on amoxicillin-clavulanate (updated January 2026) calls it the most common cause of clinically apparent drug-induced liver injury in both the U.S. and Europe. That sounds alarming, but it reflects how often the drug is prescribed. LiverTox estimates roughly 1 case per 2,000 prescriptions.
Key points from LiverTox and the FDA label:
- Clavulanate is the likely trigger. People who’ve had this reaction usually tolerate plain amoxicillin later.
- Who’s at higher risk: older adults, men, and people on longer or repeated courses.
- The usual pattern is cholestatic, meaning bile flow slows. That causes jaundice and itching more than pain.
- Timing can be delayed. Onset averages about 3 weeks after starting and can appear several weeks after the last dose.
- Most cases resolve once the drug stops, though the label notes rare deaths, usually in people with serious underlying illness.
Watch for yellow skin or eyes, dark urine, pale stools, or itching during or in the weeks after a course, and report them promptly. If you drink, our article on mixing amoxicillin with alcohol covers why going easy makes sense, especially with Augmentin’s liver warning.
Take Augmentin at the start of a meal
Plain amoxicillin can be taken with or without food. Augmentin’s label advises taking it at the start of a meal. Food helps your body absorb clavulanate and reduces stomach upset. The extended-release XR tablets should be taken at the start of a meal but not with a high-fat one, and swallowed whole.
For a fuller list of reactions, including rashes and when they matter, see amoxicillin side effects and when to call a doctor.
Allergy: same family, same risk
Augmentin is amoxicillin. If you’re allergic to amoxicillin or penicillin, you’re allergic to Augmentin. Switching between them is never a workaround. Our guide to amoxicillin allergy signs explains how to tell a true allergy from a harmless rash, and how allergy testing can clear an old label.
Why you can’t swap Augmentin tablets
With plain amoxicillin, two 250 mg capsules equal one 500 mg capsule. With Augmentin, that math breaks. Every tablet and liquid has its own ratio of amoxicillin to clavulanate, and the clavulanate dose doesn’t scale with the amoxicillin.
| Product | Amoxicillin | Clavulanate | Ratio |
|---|---|---|---|
| 250/125 tablet | 250 mg | 125 mg | 2:1 |
| 500/125 tablet | 500 mg | 125 mg | 4:1 |
| 875/125 tablet | 875 mg | 125 mg | 7:1 |
| XR tablet (dose is two tablets) | 1,000 mg each | 62.5 mg each | 16:1 |
| 250/62.5 chewable or per 5 mL | 250 mg | 62.5 mg | 4:1 |
| 400/57 chewable or per 5 mL | 400 mg | 57 mg | 7:1 |
| ES-600 per 5 mL | 600 mg | 42.9 mg | 14:1 |
The label spells out the consequences:
- Two 250/125 tablets are not the same as one 500/125 tablet. You’d get the same amoxicillin but double the clavulanate (250 mg instead of 125 mg), which means more diarrhea risk with no added benefit.
- The 250/125 tablet and the 250/62.5 chewable are not interchangeable, because the tablet has twice the clavulanate.
- Two 500 mg tablets don’t equal one XR 1,000 mg tablet. XR uses a special release design.
- The 200/28.5 and 400/57 suspensions can’t stand in for ES-600. They carry different clavulanate amounts per dose of amoxicillin.
For children, this is where errors creep in. Liquid amoxicillin-clavulanate is dosed by weight and by the amoxicillin part, and the right milliliter amount depends entirely on which concentration is in the bottle. If the pharmacy hands you a different strength than last time, the volume may change. Always use the dosing syringe from the pharmacy, never a kitchen spoon, and double-check with the pharmacist. Our amoxicillin dosage guide for adults and children explains how weight-based dosing works.
Typical dose ranges on the label
These are figures prescribers commonly work from, shared for context only. Your prescription is based on your infection, kidney function, and other factors, so follow it rather than these numbers.
- Adults, milder infections: 500/125 mg every 12 hours or 250/125 mg every 8 hours.
- Adults, more severe or respiratory infections: 875/125 mg every 12 hours or 500/125 mg every 8 hours.
- Children 3 months and older under 40 kg: 25 to 45 mg/kg/day of amoxicillin split every 12 hours, depending on the infection.
- Kidney disease: people with significantly reduced kidney function shouldn’t get the 875 mg tablet, and XR and ES-600 aren’t used in severe kidney impairment.
Cost and access
On price, the amoxicillin vs Augmentin gap is small. Both drugs are prescription-only in the U.S., and both come as low-cost generics. Generic amoxicillin is typically one of the cheapest prescriptions at any pharmacy. Generic amoxicillin-clavulanate usually costs a bit more, though with discount cards, a typical course of either often runs in the low double digits without insurance. Brand-name Augmentin costs considerably more than the generic and offers no clinical advantage.
A few practical tips:
- Prices vary widely between pharmacies. Calling two or three, or checking a discount app, can save real money.
- Specialty forms may need ordering. XR tablets and the ES-600 suspension are stocked less often than standard tablets. If a pharmacy is out, ask whether the prescriber is fine with an equivalent regimen. Never improvise a substitute yourself.
- Mixed suspensions have a short shelf life. Once the pharmacy adds water, follow the storage and discard date printed on the bottle label. It isn’t meant to be saved for later.
- Don’t use leftovers. A half bottle from last winter may be the wrong drug, the wrong strength, or expired, and taking it can mask an infection that needs a different treatment.
Questions to ask your prescriber
- Is this infection likely bacterial, and does it need an antibiotic at all?
- Would plain amoxicillin cover the likely germ, or do I need the clavulanate?
- I took an antibiotic recently (or have liver problems, or kidney disease). Does that change the choice?
- What should I do if diarrhea starts?
- When should I expect to feel better, and when should I call back?
Quick answers
Does Augmentin work faster than amoxicillin?
Not against the same germ. If the bacteria don’t make beta-lactamase, both work at the same speed. Augmentin only looks “faster” when the infection was caused by an enzyme-producing germ that plain amoxicillin couldn’t touch. Many people start feeling better within 2 to 3 days on the right drug. Finish the full course unless your prescriber says otherwise.
Can I take Augmentin if amoxicillin gave me hives?
No, not without talking to your doctor first. Augmentin contains amoxicillin, so a true amoxicillin allergy applies to both. Tell every prescriber and pharmacist about any past reaction so they can choose a safe alternative or arrange allergy testing.
Why was I switched from amoxicillin to Augmentin?
Usually because the infection didn’t improve after 2 to 3 days, which suggests an enzyme-producing germ. A recent course of amoxicillin, or certain infections like bites or eye discharge with an ear infection, can also prompt the switch. Ask your prescriber if the reason isn’t clear.
Can probiotics or yogurt prevent Augmentin diarrhea?
Evidence is mixed, and products vary widely. Taking each dose at the start of a meal is the step the label actually recommends. If you want to try a probiotic, ask your pharmacist which one and how to space it from your antibiotic doses.
Medical disclaimer: This article is for general education and doesn’t replace advice from your doctor, dentist, or pharmacist. Antibiotic choice depends on your diagnosis, allergies, other medicines, and health history. Take antibiotics only as prescribed for you, and contact a healthcare professional promptly if symptoms worsen or new ones appear.
References
- U.S. Food and Drug Administration. Augmentin (amoxicillin/clavulanate potassium) prescribing information, revised July 2026.
- Gillies M, et al. Common harms from amoxicillin: a systematic review and meta-analysis of randomized placebo-controlled trials. CMAJ, 2015.
- NIH LiverTox. Amoxicillin-Clavulanate, updated January 2026.
- Chow AW, et al. IDSA Clinical Practice Guideline for Acute Bacterial Rhinosinusitis in Children and Adults. Clinical Infectious Diseases, 2012.
- CDC. Adult Outpatient Treatment Recommendations, 2024.
- CDC. Pediatric Outpatient Treatment Recommendations, 2024 (reflecting AAP 2013 otitis media guidance).
- American Dental Association. Antibiotics for Dental Pain and Swelling chairside guide, based on the 2019 guideline.
- MedlinePlus. Amoxicillin and Clavulanic Acid, revised April 2026.
- Metlay JP, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia: ATS/IDSA guideline. American Journal of Respiratory and Critical Care Medicine, 2019.
