Keflex vs. Clindamycin
See how Keflex and Clindamycin compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Keflex is a first-generation cephalosporin best suited for common infections like skin, urinary tract, and respiratory infections, while clindamycin covers anaerobic infections and penicillin-allergic cases.
Clindamycin carries a boxed warning for C. difficile-associated diarrhea and colitis, a risk that is not called out with a boxed warning on Keflex's label.
Keflex needs a lower dose in people with reduced kidney function, while clindamycin is cleared mainly by the liver and does not require renal dose changes.
Keflex vs. Clindamycin Drug Summary
Keflex
Keflex (cephalexin) is a first-generation cephalosporin antibiotic used to treat infections such as skin, respiratory tract, ear, bone, and urinary tract infections. It comes as an oral capsule, tablet, or liquid, usually taken every 6 to 12 hours depending on the infection.
Clindamycin
Clindamycin is a lincosamide antibiotic used for serious anaerobic, skin, bone, and abdominal infections, and often chosen for people who cannot take penicillin-based drugs. It is available as an oral capsule, IV or IM injection, and topical or vaginal formulation, with oral doses typically taken every 6 hours.
Keflex vs. Clindamycin Side Effects
Keflex
Clindamycin
Keflex vs. Clindamycin Dosage
Keflex
Clindamycin
| 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 |
| STAGE | DOSE | WHEN |
| Starting dose | 150 mg every 6 hours | At the start |
| Maximum dose | up to 4800 mg/day IV | 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 |
Clindamycin
| STAGE | DOSE | WHEN |
| Starting dose | 150 mg every 6 hours | At the start |
| Maximum dose | up to 4800 mg/day IV | If needed |
| Dose changes | 6 increases | As tolerated |
Keflex vs. Clindamycin Indications
Keflex
Keflex is FDA-approved for a range of common bacterial infections caused by susceptible organisms, including respiratory, ear, skin, bone, and urinary tract infections. It is sometimes used off-label to help prevent infection after certain surgical procedures.
Respiratory tract infections
Otitis media
Skin and skin structure infections
Bone infections
Genitourinary tract infections
Clindamycin
Clindamycin is FDA-approved for serious infections caused by anaerobic bacteria as well as certain streptococcal, staphylococcal, and pneumococcal infections, including skin, bone, and abdominal infections. Off-label, it is used for toxoplasmosis, malaria, and as a dental or surgical antibiotic in penicillin-allergic patients.
Serious anaerobic bacterial infections
Skin and skin structure infections
Bone and joint infections
Intra-abdominal infections
Gynecological infections
Keflex vs. Clindamycin Pros and Cons
Keflex
Keflex has decades of use as a first-line option for common infections and does not carry a boxed warning for C. difficile colitis, though the risk still exists. Its clearance depends on the kidneys, so people with reduced kidney function need a lower dose to avoid seizure risk.
Pros
Not associated with a boxed C. diff warning
Long-standing safety record after decades of use
Simple dosing schedule (every 6 to 12 hours)
Effective for common outpatient infections like UTIs and skin infections
Cons
Not effective against anaerobic bacteria
Requires dose adjustment in kidney impairment (seizure risk)
Cross-reactivity risk in penicillin-allergic patients
Clindamycin
Clindamycin reaches anaerobic bacteria that Keflex does not cover and offers oral, IV, topical, and vaginal formulations for different types of infections. It carries a boxed warning for C. difficile-associated diarrhea and colitis, a risk described more seriously than on Keflex's label.
Pros
Covers anaerobic bacteria Keflex does not treat
Available in oral, IV, topical, and vaginal forms
Preferred option for penicillin-allergic patients
No renal dose adjustment needed (hepatic clearance)
Cons
Boxed warning for C. difficile-associated colitis
Oral capsules can cause esophagitis if not taken with fluids
Should not be combined with erythromycin (antagonism)
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