Augmentin vs. Cephalexin
See how Augmentin and Cephalexin compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Augmentin combines amoxicillin with clavulanate, letting it fight bacteria that produce beta-lactamase enzymes, while Cephalexin is a cephalosporin without that added protection.
Both antibiotics commonly cause diarrhea, nausea, and vomiting, but Augmentin's stomach-related side effect rates are more clearly documented on its FDA label.
Cephalexin generally costs less and has been used safely since the early 1970s, while Augmentin covers a broader range of resistant bacteria.
Augmentin vs. Cephalexin Drug Summary
Augmentin
Augmentin is a penicillin-class antibiotic that combines amoxicillin with clavulanate, a beta-lactamase inhibitor that extends its reach to resistant bacteria. It treats respiratory, ear, sinus, skin, and urinary tract infections. It comes as a tablet, chewable tablet, or oral suspension, taken every 8 to 12 hours depending on the dose.
Cephalexin
Cephalexin is a first-generation cephalosporin antibiotic used for respiratory, ear, skin, bone, and urinary tract infections caused by susceptible bacteria. It has been prescribed since the early 1970s and is only available as a generic. It comes as a capsule, tablet, or oral suspension, typically taken every 6 to 12 hours.
Augmentin vs. Cephalexin Side Effects
Augmentin
Cephalexin
Augmentin vs. Cephalexin Dosage
Augmentin
Cephalexin
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg/125 mg every 8 hrs | At the start |
| Maximum dose | 2000 mg/125 mg every 12 hrs | If needed |
| Dose changes | 4 increases | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 25-50 mg/kg/day divided | At the start |
| Maximum dose | 1 to 4 g/day divided | If needed |
| Dose changes | 4 increases | As tolerated |
Augmentin
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg/125 mg every 8 hrs | At the start |
| Maximum dose | 2000 mg/125 mg every 12 hrs | If needed |
| Dose changes | 4 increases | As tolerated |
Cephalexin
| STAGE | DOSE | WHEN |
| Starting dose | 25-50 mg/kg/day divided | At the start |
| Maximum dose | 1 to 4 g/day divided | If needed |
| Dose changes | 4 increases | As tolerated |
Augmentin vs. Cephalexin Indications
Augmentin
Augmentin is FDA-approved for common bacterial infections including sinusitis, ear infections, and pneumonia, including strains that produce beta-lactamase enzymes. It is not effective against viral infections and should not be used in patients with a history of penicillin anaphylaxis.
Lower respiratory tract infections
Acute bacterial otitis media
Acute bacterial sinusitis
Skin and skin structure infections
Urinary tract infections
Cephalexin
Cephalexin is FDA-approved for respiratory, ear, skin, bone, and urinary tract infections caused by susceptible bacteria such as streptococci and staphylococci. It is sometimes used off-label for acne treatment and surgical infection prevention, though these are not FDA-approved indications.
Respiratory tract infections
Otitis media
Skin and skin structure infections
Bone infections
Genitourinary tract infections including prostatitis
Augmentin vs. Cephalexin Pros and Cons
Augmentin
Augmentin's added clavulanate lets it work against bacteria that would otherwise resist amoxicillin alone, giving it a broader reach for infections like sinusitis and skin infections. That broader coverage comes with a higher rate of stomach-related side effects and a monthly cost that runs higher than many generic alternatives.
Pros
Covers beta-lactamase-producing resistant bacteria
Available in chewable tablets and pediatric suspension
FDA-approved for community-acquired pneumonia (XR)
Effective when amoxicillin alone would fail
Cons
Higher diarrhea rate than many oral antibiotics (up to 9%)
Contraindicated with any penicillin allergy history
Carries a hepatotoxicity warning
Typically $80 to $150 a month, more than Cephalexin
Cephalexin
Cephalexin is a first-generation cephalosporin with a long track record for common skin, respiratory, and urinary infections. It costs less than Augmentin and can sometimes be used in penicillin-sensitive patients, but it does not cover bacteria that produce beta-lactamase enzymes.
Pros
Typically $10 to $65 per course, less than Augmentin
Long-standing safety record since the early 1970s
May be an option for some penicillin-sensitive patients
Flexible dosing from every 6 to 12 hours
Cons
No activity against beta-lactamase-producing bacteria
Requires dose adjustment in kidney impairment
Cross-reactivity risk in true penicillin allergy
Not available as a branded or extended-release product
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