Clavamox is not the same as amoxicillin. Clavamox contains amoxicillin plus a second ingredient called clavulanate potassium, which protects the antibiotic from being destroyed by resistant bacteria. Plain amoxicillin is a single-ingredient antibiotic. This distinction matters because Clavamox can treat infections that amoxicillin alone cannot.
What Clavamox Actually Contains
Clavamox is a veterinary antibiotic made of two active compounds: amoxicillin (the antibiotic that kills bacteria) and clavulanate potassium (an enzyme blocker with almost no antibacterial power on its own). Veterinary tablets always use a fixed 4:1 ratio, meaning four parts amoxicillin to one part clavulanate. A 250 mg Clavamox tablet, for example, contains 200 mg of amoxicillin and 50 mg of clavulanate.
The human equivalent is sold under the brand name Augmentin. While the active ingredients are the same, the ratios differ. Human formulations range from 2:1 to 7:1 amoxicillin to clavulanate, and the milligram number on the label refers only to the amoxicillin content. A human “250 mg” tablet actually contains 250 mg of amoxicillin plus 125 mg of clavulanate, making the total 375 mg. This labeling difference is one reason you should never substitute one for the other without veterinary guidance.
Why the Extra Ingredient Matters
Some bacteria produce an enzyme called beta-lactamase that breaks apart amoxicillin before it can do its job. When your pet has an infection caused by one of these resistant bacteria, plain amoxicillin is essentially useless. Clavulanate solves this problem by permanently binding to that enzyme and shutting it down, giving the amoxicillin a clear path to kill the bacteria.
This makes Clavamox effective against a broader range of organisms. Plain amoxicillin works well against many common gram-positive and gram-negative bacteria, but it fails against beta-lactamase producers like certain strains of E. coli, Klebsiella, Proteus, and Staphylococcus. Clavamox handles all of these. It also covers most anaerobic bacteria, including Bacteroides fragilis, which can cause serious abdominal and wound infections.
When a Vet Chooses One Over the Other
If the infection is likely caused by bacteria that don’t produce beta-lactamase, plain amoxicillin works fine and costs less. Simple urinary tract infections, some dental infections, and certain skin conditions in dogs and cats often respond well to amoxicillin alone.
Clavamox gets prescribed when the infection is more complex, involves resistant bacteria, or when the vet suspects a mixed infection with both susceptible and resistant organisms. Skin infections with Staphylococcus involvement, bite wound infections, and respiratory infections are common reasons a vet reaches for Clavamox instead of plain amoxicillin. It’s also a go-to choice when the specific bacteria hasn’t been identified yet, since it covers a wider range.
Dosing for Dogs and Cats
Dogs typically receive 6.25 mg per pound of body weight, given twice daily. So a 40-pound dog would get a 250 mg tablet twice a day. Cats have a simpler standard dose: 62.5 mg twice daily regardless of size, though your vet may adjust this. Treatment courses commonly run 7 to 14 days depending on the type and severity of infection.
Clavamox comes in chewable tablets (62.5 mg, 125 mg, 250 mg, and 375 mg) and a liquid suspension at 62.5 mg per milliliter. The liquid form is especially useful for cats and small dogs that are difficult to pill.
Side Effects to Watch For
The clavulanate component is harder on the stomach than amoxicillin alone. Vomiting, diarrhea, and reduced appetite are the most common side effects, and they tend to be more frequent with Clavamox than with plain amoxicillin. Giving the medication with food usually helps reduce nausea. If your pet has persistent vomiting or bloody diarrhea, that warrants a call to your vet.
Clavamox is contraindicated in animals with a known allergy to penicillins or cephalosporins. These drug families are chemically related, so a reaction to one often means a reaction to the other.
Storing the Liquid Form
If your vet dispenses Clavamox drops (the liquid suspension), it needs to be refrigerated after mixing and used within 10 days. After that window, the medication loses potency and should be discarded. The tablets are more shelf-stable and don’t require refrigeration, making them the more convenient option when the pet will tolerate them.