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
Keflex
Doxycycline vs. Keflex Dosage
Doxycycline
Keflex
| STAGE | DOSE | WHEN |
| Starting dose | 200 mg total | Day 1 |
| Maximum dose | 100 mg twice daily | If needed |
| Dose changes | 6 increases | As tolerated |
| 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
| 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
| 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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