What Is The Difference Between Amoxicillin And Augmentin?

In our latest question and answer, our pharmacist discusses the difference between amoxicillin and Augmentin.

5 min read Updated Jun 2026 2,314 views
What Is The Difference Between Amoxicillin And Augmentin?
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Harriet asked

I was prescribed amoxicillin a few months ago for strep throat. I have another infection now, and my doctor said they gave me something 'stronger'. I'm looking at the bottle and it says amoxicillin/clavulanic acid. How is this any different than what I had before?

Mar 06, 2023
The quick answer
  • Amoxicillin is an antibiotic that works against many bacterial infections but some bacteria produce an enzyme called beta-lactamase that destroys it.
  • Augmentin contains amoxicillin plus clavulanic acid, which blocks the beta-lactamase enzyme and prevents it from destroying the amoxicillin.
  • Because of clavulanic acid, Augmentin is effective against a wider range of bacteria than amoxicillin alone.
A quick summary of Dr. Brian Staiger, PharmD's full answer below, condensed by AI from that answer only (not from any outside source). The pharmacist's answer is the source of record.
Medications in this answer — tap to explore

Quick Answer

Amoxicillin is a broad-spectrum 'beta-lactam' antibiotic used to treat a variety of common bacterial infections. Some bacteria produce an enzyme known as 'beta-lactamase', which destroys amoxicillin and makes them resistant to the antibiotic.

Augmentin contains two compounds, amoxicillin, and clavulanic acid. Clavulanic acid is a beta-lactamase inhibitor and prevents the beta-lactamase enzyme from breaking down amoxicillin.

Therefore, by combining amoxicillin with clavulanic acid, Augmentin provides a broader spectrum of antibacterial activity, and is effective against a wider range of bacteria than amoxicillin alone.

Detailed Answer

Thanks so much for reaching out to us!

As mentioned in the quick answer section above, Augmentin contains two compounds, the antibiotic amoxicillin, and the beta-lactamase inhibitor clavulanic acid. Let's talk about both of these in detail.

What Is Amoxicillin?

Amoxicillin is a derivative of penicillin and is oftentimes referred to as an 'amino-penicillin'.

Penicillin is known for its activity against a certain type of bacteria known as 'gram-positive' bacteria. Amoxicillin has a broader spectrum of activity and is also effective against many 'Gram-negative' bacteria that aren't affected by penicillin.

As a quick aside, when we talk about bacteria, we often divide them into two groups: Gram-positive and Gram-negative. There are certainly more that don't fall into these two distinct categories, but this is a good entry-level distinction.

This 'Gram-positive', 'Gram-negative' classification is based on a test that scientists use to study bacteria called the 'Gram stain'. Gram-positive bacteria have a thick outer layer called a peptidoglycan layer, which is stained purple by the Gram stain. Gram-negative bacteria, on the other hand, have a thinner peptidoglycan layer and an outer membrane that is not stained by the Gram stain.

How Does It Differ From Penicillin?

Antibiotics, penicillins, in particular, have major differences among the range of bacteria against which they are active.

Penicillin, as stated, generally works only on gram-positive bacteria (although there are exceptions) while amoxicillin has a broader coverage and is distinguished by its activity against different types of gram-negative bacteria.

Both amoxicillin and penicillin work by interrupting bacterial cell wall synthesis. They do this by binding to one or more of what are known as 'penicillin-binding proteins (PBPs)' which in turn inhibits the final step of bacterial cell wall synthesis, which results in the bacteria starting to break down and eventually burst or 'lyse'.

Penicillin is an antibiotic that can bind to certain proteins on the cell wall of many types of gram-positive bacteria. However, gram-negative bacteria have an extra layer of protection in their cell walls that makes it harder for penicillin to work. This extra layer includes things such as 'lipopolysaccharides' and 'porins', which create a barrier that reduces the ability of penicillin to penetrate and disrupt the synthesis of the cell wall. As a result, penicillin is not as effective against gram-negative bacteria as it is against gram-positive bacteria.

Amoxicillin is better able to penetrate the outer membrane of gram-negative bacteria when compared to penicillin, which makes it more effective against these types of bacteria.

What Is Clavulanic Acid?

One of the mechanisms some bacteria use to resist penicillin-type antibiotics is to produce an enzyme known as beta-lactamase.

This enzyme destroys a key component contained in the chemical structure of penicillin-type antibiotics, including amoxicillin, known as the beta-lactam ring. This structure is essential to the antibiotic's ability to kill bacteria by disrupting the formation of their cell walls. If beta-lactam is destroyed, the antibiotic will no longer be effective.

Clavulanic Acid is a beta-lactamase inhibitor.

Clavulanic Acid inhibits the beta-lactamase enzyme, preventing it (beta-lactamase) from destroying the antibiotic before it can start working.

Analogy

Think of it like this.

Pretend that the bacteria causing your infection acts as a lock and that amoxicillin acts as a key to destroy the bacteria. Some bacteria have evolved to produce a chemical called beta-lactamase that destroys the key before it can reach the lock. In this scenario, amoxicillin becomes ineffective in eradicating the infection.

To overcome this problem, clavulanic acid can be added to amoxicillin, which works to neutralize the beta-lactamase chemical produced by bacteria. With clavulanic acid, the amoxicillin key can reach the lock (bacteria) without being destroyed first by the beta-lactamase chemical. This makes the combination of amoxicillin and clavulanic acid an effective treatment against bacteria that produce beta-lactamase.

What Extra Coverage Does Augmentin Provide Over Amoxicillin?

To reiterate, Augmentin is a brand-name antibiotic that contains amoxicillin and clavulanic acid.

It is used in certain scenarios to effectively combat bacteria that produce beta-lactamase, which can render amoxicillin ineffective. Therefore, it would be accurate to say it has broader antibacterial coverage when compared to both penicillin and amoxicillin alone.

Compared to amoxicillin alone, Augmentin is effective against more strains of bacteria, such as Staphylococcus aureus and beta-lactamase-producing Haemophilus influenzae. In addition, at higher dosages, Augmentin can also target certain beta-lactamase-producing Enterobacteriaceae, which are known to cause urinary and respiratory tract infections.

Final Words

I hope this answer provided what you were looking for!

I always hesitate to say a certain antibiotic is 'stronger' when it really comes down to whether or not particular bacteria are susceptible to the effects of the antibiotic in question.

Regardless, since Augmentin does work against more types of bacteria than amoxicillin, I suppose you could say it is stronger in that sense.

Reach back out anytime!

References & sources
  1. Augmentin (amoxicillin/clavulanate) in the treatment of community-acquired respiratory tract infection: a review of the continuing development of an innovative antimicrobial agent — PubMed
  2. Amoxicillin Clavulanate — NIH
  3. Further experience with augmentin in the treatment of skin infections — PubMed
  4. Amoxicillin — PubMed
Glossary — Terms in This Answer
Beta-lactam
A key chemical structure found in penicillin-type antibiotics that is essential for killing bacteria by disrupting their cell walls.
Beta-lactamase
An enzyme produced by some bacteria that destroys the beta-lactam ring and makes antibiotics like amoxicillin ineffective.
Beta-lactamase inhibitor
A substance that blocks the beta-lactamase enzyme from destroying antibiotics, allowing them to work effectively.
Gram-positive bacteria
Bacteria with a thick outer peptidoglycan layer that are typically susceptible to penicillin-type antibiotics.
Gram-negative bacteria
Bacteria with a thinner peptidoglycan layer and an outer membrane that makes them harder for some antibiotics to penetrate.
Penicillin-binding proteins (PBPs)
Proteins on bacterial cell walls that antibiotics attach to in order to stop the bacteria from building their protective walls.
Lyse
To burst or break apart, as bacteria do when their cell walls are disrupted by antibiotics.
Lipopolysaccharides
Complex molecules in the outer membrane of gram-negative bacteria that help protect them from antibiotics like penicillin.
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Dr. Brian Staiger, PharmD
About the pharmacist

Dr. Brian Staiger, PharmD

Clinical Pharmacy

Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified

Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...

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