Cephalexin Uses, Side Effects & Dosage Guide

What is Cephalexin

Cephalexin is a kind of antibiotic medicine which common shape is with crystal powder. Color of Cephalexin is white or yellow. Cephalxin melts in water and doesn’t melt in ethanol, chloroform or ether. Cephalexin is semi-synthetic broad-spectrum antibiotic and belongs to first generation cephalspoins. It is fit for curing mild infection that caused by penicillinase sensitive bacteria in respiratory tract, urinary tract, and skin soft tissue. Cephalexin is ethical drug. It has allegorical stimulation reaction. Patient should buy the medicine under guidance of doctor.



Pharmacological effect is that Cephalexin binds one or more penicillin binding proteins (PBPs) of bacteria and refrain generation of bacterial cell wall synthesis in dividing cells, which in turn has an antibacterial effect. Antibacterial spectrum of Cephalexin is similar with Cefalotin, but the antibacterial activity property of Cefalotin is weaker than that of Cephalexin. Besides Enterococcus, Methicillin-resistant Staphylococcus aureus, the Gram-positive cocci is sensitive to Cephalexin. The affected bacterium is influenced differently. Neisseria is affected fairly well; Haemophilus is affected poorly; a part of the E, Coli, Proteus mirabilis, Klebsiella pneumonia, Salmonella are affected in some certain, other Enterobacter bacteria, Acinetobacter and Pseudomonas aeruginosa, and Bacteroides fragilis resistant to cephalexin.


Cephalexin liquid is well absorbed. One takes Cephalexin 500mg oral when empty stomach, the blood plasma concentration peak will occur in an hour, which is 18μg/ml. Distribution volume of the drug is 0.26L/kg and drug can be found in sputum, pus, joint cavity exudates, amniotic fluid, cord blood, lung, liver, spleen, and kidney. Among these, bile has higher plasma concentration. Cephalexin is difficult to permeate the blood-brain barrier, but can permeate breast milk. Breastfeeding women drink 0.5g Cephalexin oral and concentration of Cephalexin in breast milk is about 5μg/ml. The binding rate of Cephalexin and protein is about 10%~15%. Half-value period of Cephalexin in human body is 0.6 hour to 1 hour, while half-value period may be extended to 5~30 hours when patient has gotten renal dysfunction and half-value period is 6.3 hours in newborn. Cephalexin is not metablolized in the body and is filtered by glomerular in the prototype and discharged with tubular secretion. In addition, 5% of the oral dose is discharged by bile. 24 hours later, about 80% of administered Cephalexin is discharged via urine. Peak concentration in urine can reach 2,200μg/ml when drinking 500 mg Cephalexin oral. So Cephalexin is especially used to treat genitourinary system. Removing Cephalexin method can be hemodialysis or peritoneal dialysis.

Cephalexin Uses

Cephalexin is used to mitigate physical discomfort caused by bacterial infection. Indications that can be mitigated by Cephalexin include urinary tract infections, skin soft tissue infections and respiratory tract infections. Respiratory tract infections can be acute tonsillitis caused by sensitive bacteria, angina, otitis media, sinusitis, bronchitis and pneumonia. When drinking Ceohalexin oral, it is suggested to drink plenty of water so as to dilute urine.

Cephalexin Dosage

Dosage of Cephalexin depends on condition of individual body. It is forbidden to drink too much Cephalexin so as not to restrain function of kidney and form hematuria. Generally child dosage should be less than adult. Dosage for adult is 250~500 mg, 6 hours interval. Maximum dosage is 4g every day. Child dosage is 25~50 mg every time. Maximum dosage should not exceed 200mg every day.

Drug Interactions

It can delay discharging Cephalexin through renal exertion and elevate phasma concentrationof Cephalexin when taking probencid at the same time.
Drinking Cephalexin oral together while taking cholestyramine, average plasma peak concentration of Cephalexin can reduce to minimum.
Drinking Cephalexin oral together with taking aminoglycoside drug can make nephrotoxicity increase.
Immune response to live typhoid vaccine may get faint when taking Cephalexin. The possible cause is that Cephalexin has antimicrobial activity effect to typhoid Salmonella.

Cephalexin Side Effects

Individual who is allergic to one kind of Cephalexin may be allergic to other kinds of Cephalexin. Individual who is allergic to penicillins, penicillin derivatives or penicillamine may be allergic to cephalosporins medicines.

  • Lactating women is cautious to drinking Cephalexin ora for Cephalexin can melt in breast milk and be drunk by baby to temporarily change balance of bacteria in baby’s gut to cause diarrhea.
  • Pregnant women should be cautious to drink Ceohalexin and should be guided by doctor’s description.
  • Child under six years should be cautious to drink Cephalexin and should be careful to control dosage.
  • Server liver and renal dysfunction because existing of Cephalexin can increase load of liver and renal as well as reduce function of liver and renal.
  • Individual who has history of gastrointestinal disease, especially ulcerative colitis, enteritis or antibiotic-associated colitis.Cephalexin can have impact on diagnostic value or test result. Direct anti-human globulin (Coombs) test may be positive because of impaction of the drug left; Glucose in urine test with Copper sulfate method may appear false positive because of drug left.

Adverse Reactions (Side Effects Of Cephalexin)

  • There may be common rash, urticaria, erythema, drug fever and other allergic symptoms when individual drinks Cephalexin oral, and occasionally there is anaphylactic shock.
  • Hepatotoxicity because of drug distributed in liver: A small number of patients may have abnormal liver function after treatment with Cephalexin. And serum alanine aminotransferase aminotransferase, aspartate aminotransferase and alkaline phosphatase transient temporary rise.
  • Nervous system reactions: a few patients can be dizziness, diplopia, tinnitus, convulsions and other nervous system reactions.
  • Gastrointestinal reactions caused by drinking Cephalexin: nausea, vomiting, diarrhea, and abdominal discomfort and other gastrointestinal symptoms are most common, occasionally there is pseudomembranous colitis.
  • Nephrotoxicity because of drug distributed in kidney: a few patients may have symptom of temporary urea nitrogen, creatinine, creatinine increased, occasionally proteinuria, oliguria after treatment.
  • Blood system: occasionally there will be symptom of decreased hemoglobin, thrombocytopenia, neutropenia, eosinophilia etc. after treatment.
  • Other adverse reaction: The long-term medication of Cephalexin can cause flora, double infection and cause deficiency of vitamin K, and vitamin B.
  • Over drinking of Cephalexin may be poisonous, symptom may be sick gastrointestinal reactions, urticaria, rash, body itching, drug fever, addicted to increase neutrophil eosin etc. allergic reaction, and double infection in perineum.

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