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

Most common
Diarrhea (up to 9%)
Nausea (up to 3%)
Vomiting (up to 1%)
Skin rash/urticaria (up to 3%)

Cephalexin

Most common
Diarrhea (rate not specified in FDA label)
Nausea (rate not specified in FDA label)
Vomiting (rate not specified in FDA label)
Dyspepsia (rate not specified in FDA label)

Augmentin vs. Cephalexin Dosage

Augmentin

Dosage
Dosage Table
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

Dosage
Dosage Table
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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