Keflex vs. Cephalexin

See how Keflex and Cephalexin compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Keflex and cephalexin are the same drug; Keflex was the original brand name, but it has been discontinued in the U.S., so pharmacies now dispense generic cephalexin even for a Keflex prescription.

  • Both are first-generation cephalosporin antibiotics approved for respiratory, skin, bone, and urinary tract infections, with identical dosing and side effect profiles.

  • Generic cephalexin usually costs less than what Keflex historically cost, roughly $10 to $65 per course versus $53 to $95.

Keflex vs. Cephalexin Drug Summary

Keflex

Keflex is the original brand name for cephalexin, a first-generation cephalosporin antibiotic approved in 1971. It treats bacterial infections of the respiratory tract, skin, bones, and urinary tract, and is taken by mouth as a capsule, tablet, or liquid. Brand-name Keflex tablets are no longer manufactured in the U.S., so a Keflex prescription is filled with generic cephalexin.

Cephalexin

Cephalexin is a first-generation cephalosporin antibiotic first approved in 1971, now sold only as a generic since the Keflex brand was discontinued. It treats bacterial infections of the respiratory tract, skin, bones, urinary tract, and ear, and is taken by mouth as a capsule, tablet, or liquid. It's also used off-label as an adjunct for acne and for surgical infection prevention.

Keflex vs. Cephalexin Side Effects

Keflex

Most common
Vomiting (rate not quantified in current label)
Nausea (rate not quantified in current label)
Dyspepsia (rate not quantified in current label)
Diarrhea (rate not quantified in current label)

Cephalexin

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

Keflex vs. Cephalexin Dosage

Keflex

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 25-50 mg/kg/day divided At the start
Maximum dose Up to 4 g/day divided If needed
Dose changes 3 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

Keflex vs. Cephalexin Indications

Keflex

Keflex is FDA-approved for common bacterial infections, including respiratory tract infections, ear infections, skin infections, bone infections, and urinary tract infections. Doctors sometimes prescribe it off-label to help prevent surgical site infections.

  • Respiratory tract infections

  • Otitis media (ear infections)

  • Skin and skin structure infections

  • Bone infections

  • Genitourinary tract infections

Cephalexin

Cephalexin carries the same FDA approvals as Keflex, covering infections caused by susceptible bacteria such as streptococci, staphylococci, and E. coli. It's also used off-label as an adjunct antibacterial for acne and for surgical infection prevention, though these aren't FDA-approved uses.

  • Respiratory tract infections (strep, pneumococcus)

  • Otitis media (H. influenzae, staph, strep)

  • Skin infections (staph, strep)

  • Bone infections (staph, Proteus)

  • Genitourinary infections, including prostatitis

Keflex vs. Cephalexin Pros and Cons

Keflex

Keflex refers to the original branded cephalexin, though that brand is no longer manufactured in the U.S. Clinically, it works identically to generic cephalexin, with the same effectiveness, dosing, and safety profile.

Pros

  • Widely recognized brand name that many prescribers and patients still refer to out of habit

  • Decades of clinical use and familiarity among prescribers since its 1971 approval

  • Served as the original reference product that generic cephalexin versions are measured against for bioequivalence

Cons

  • Brand-name Keflex tablets are no longer manufactured in the U.S.; a prescription is filled with generic cephalexin

  • Typically costs more, roughly $53 to $95 for a 20-capsule course, than buying cephalexin directly

  • Offers no clinical advantage over generic cephalexin since they are the same active drug

Cephalexin

Cephalexin is the generic form of the same antibiotic once sold as Keflex, and it's now the only version stocked at most U.S. pharmacies. It offers identical effectiveness and safety to brand-name Keflex, usually at a lower price.

Pros

  • Is the version actually available at pharmacies today, since Keflex brand tablets are discontinued

  • Usually costs less, roughly $10 to $65 per course, than historical Keflex pricing

  • Available from multiple manufacturers, which can help avoid single-source supply shortages

Cons

  • Pill appearance (shape, color) can vary between manufacturers, which sometimes confuses refills

  • Some patients associate the Keflex name with quality and feel uncertain switching to an unfamiliar generic

  • Occasionally runs short at individual pharmacies during high-demand periods, since it's the sole supply source for this drug

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