Doxycycline vs. Keflex

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

Key Takeaways

  • Doxycycline covers a broader range of infections, including tick-borne and rickettsial diseases, while Keflex is used mainly for skin, respiratory, bone, and urinary infections.

  • Both drugs commonly cause stomach upset, but doxycycline also carries a photosensitivity risk that Keflex does not share.

  • Doxycycline is generally cheaper and dosed less often, while Keflex is considered safer during pregnancy and in young children.

Doxycycline vs. Keflex Drug Summary

Doxycycline

Doxycycline is a tetracycline-class antibiotic used to treat a wide range of bacterial infections, including tick-borne rickettsial diseases, respiratory infections, and sexually transmitted infections. It comes as an oral capsule or tablet, usually started at a higher dose on day one and then reduced to once or twice daily.

Keflex

Keflex (cephalexin) is a first-generation cephalosporin antibiotic used to treat common bacterial infections of the skin, respiratory tract, bones, and urinary system. It's taken as an oral capsule or tablet, usually two to four times a day depending on how severe the infection is.

Doxycycline vs. Keflex Side Effects

Doxycycline

Most common
Vomiting
Nausea
Diarrhea
Rash

Keflex

Most common
Vomiting
Nausea
Diarrhea
Dyspepsia

Doxycycline vs. Keflex Dosage

Doxycycline

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 200 mg total Day 1
Maximum dose 100 mg twice daily If needed
Dose changes 6 increases As tolerated

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

Doxycycline vs. Keflex Indications

Doxycycline

Doxycycline is FDA-approved for a wide variety of infections, including rickettsial diseases like Rocky Mountain spotted fever, sexually transmitted infections, and respiratory infections. It's also used for anthrax exposure prophylaxis and, at lower doses, for severe acne.

  • Rocky Mountain spotted fever and other rickettsial infections

  • Chlamydia and uncomplicated gonorrhea

  • Respiratory tract infections

  • Anthrax post-exposure prophylaxis

  • Adjunctive therapy for severe acne

Keflex

Keflex is FDA-approved for common bacterial infections, including respiratory tract infections, ear infections, and skin and skin structure infections. It's also approved for bone infections and infections of the genitourinary tract.

  • Respiratory tract infections

  • Otitis media (ear infections)

  • Skin and skin structure infections

  • Bone infections

  • Genitourinary tract infections

Doxycycline vs. Keflex Pros and Cons

Doxycycline

Doxycycline covers a broader spectrum of infections than Keflex, including tick-borne and rickettsial diseases, and is generally taken less often after the first day. Its main tradeoffs are boxed warnings around pregnancy and young children, plus a real risk of sun sensitivity.

Pros

  • Treats a broader range of infections, including tick-borne and rickettsial diseases

  • Once-daily maintenance dosing after the first day for many infections

  • Also approved for anthrax exposure prophylaxis and adjunctive acne treatment

  • Lower typical cost, roughly $10 to $40 a month versus $53 to $95 for a Keflex course

Cons

  • Boxed warnings for tooth discoloration and fetal harm limit use in pregnancy and young children

  • Can cause photosensitivity, requiring sun protection during treatment

  • Must be taken with adequate fluids to avoid esophageal irritation

Keflex

Keflex works well for common skin, respiratory, and urinary infections and is considered safer than doxycycline during pregnancy and in early childhood. Its main tradeoffs are more frequent daily dosing and a narrower range of approved uses.

Pros

  • Considered safe during pregnancy, unlike doxycycline

  • No photosensitivity risk

  • Specifically approved for bone and genitourinary tract infections

  • Well-tolerated across a wide age range, including young children

Cons

  • Requires more frequent dosing, up to four times daily for some infections

  • Costs more than doxycycline for a typical course, roughly $53 to $95 versus $10 to $40

  • Not effective against Pseudomonas or Acinetobacter infections

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