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Cefalexin information from DrugsUpdate  

See Available Brands of Cefalexin in India

P - Caution when used during pregnancy
L - Caution when used during lactation
FI - Food*
LI - Lab*

Cefalexin or cephalexin is a first-generation cephalosporin antibiotic, introduced in 1967 by Eli Lilly and Company. It is an orally administered agent with a similar antimicrobial spectrum to the intravenous agents cefalotin and cefazolin. It is commonly marketed under the trade name Keflex (Lilly), Sporidex (Ranbaxy) or Nufex.



Cefalexin binds to one or more of the penicillin-binding proteins (PBPs) which inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell wall, thus inhibiting biosynthesis and arresting cell wall assembly resulting in bacterial cell death.


Almost completely absorbed from the GI tract with peak plasma concentrations after 1 hour (oral); may be delayed if taken with food.

Widely distributed but does not penetrate the CSF; bile (therapeutic concentrations). Crosses the placenta and enters the breast milk (small amounts). Protein-binding: Up to 15%

Not metabolised.


Via the urine within 6 hours by glomerular filtration and renal tubular secretion (>80% as unchanged); via the bile. May be removed by haemodialysis and peritoneal dialysis; 1 hour (elimination half-life).

Cefalexin Indications / Cefalexin Uses

Information Not Available

Cefalexin Adverse Reactions / Cefalexin Side Effects

Pain at injection site; hypersensitivity; GI disturbances; eosinophilia, neutropenia, leucopenia, thrombocytopenia.

Potentially Fatal: Anaphylactic reactions; nephrotoxicity.


Monitor patient's response to therapy. Instruct patient to notify health care provider if infection does not appear to improve or worsens. Monitor prothrombin time in patients on anticoagulants. Monitor patient for adverse reactions and signs of superinfection.

Special Precautions

Hypersensitivity to penicillins; pseudomembranous colitis; renal failure; pregnancy and lactation.

Other Drug Interactions

Probenecid produces higher and prolonged serum levels.

Potentially Fatal: Increased nephrotoxicity with aminoglycosides and furosemide.

Other Interactions

Food Interaction
Rate of absorption is delayed by food.


Susceptible infections
Adult: 1-2 g daily given in divided doses at 6-, 8-, 12-hours intervals, increased to 6 g in deep-seated infections.
Child: 25-100 mg/kg daily in divided doses. Max: 4 g daily.
CrCl (ml/min)    Dosage Recommendation
40-50               Max: 3 g daily.
10-40               Max: 1.5 g daily.
<10                  Max: 750 mg daily.

Prophylaxis of recurrent urinary tract infections
Adult: 125 mg at night.
CrCl (ml/min)    Dosage Recommendation
40-50               Max: 3 g daily.
10-40               Max: 1.5 g daily.
<10                  Max: 750 mg daily.


May be taken with or without food. (May be taken with meals to reduce GI discomfort.)

List of Contraindications

Cefalexin and Pregnancy

Caution when used during pregnancy

Category B: Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).

Cefalexin and Lactation

Caution when used during lactation

Cefalexin and Children

Cephalosporins may accumulate in newborns.

Cefalexin and Geriatic

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

Cefalexin and Other Contraindications

Hypersensitivity to cephalosporins


Store at 25°C

Lab interference

Store at 25°C

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