Cautions
Contraindications
- Known hypersensitivity to cephalexin or other cephalosporins.
Warnings/Precautions
Warnings
Superinfection/Clostridium difficile-associated Diarrhea and Colitis
Possible emergence and overgrowth of nonsusceptible bacteria or fungi with prolonged use. Careful observation of the patient is essential. Institute appropriate therapy if superinfection occurs.
Treatment with anti-infectives may permit overgrowth of Clostridium difficile. C. difficile-associated diarrhea and colitis (CDAD; also known as antibiotic-associated diarrhea and colitis or pseudomembranous colitis) has been reported with nearly all anti-infectives, including cephalexin, and may range in severity from mild diarrhea to fatal colitis.
Consider CDAD if diarrhea develops during or after therapy and manage accordingly. Careful medical history is necessary since CDAD has been reported to occur as late as 2 months or longer after anti-infective therapy is discontinued.
If CDAD is suspected or confirmed, the anti-infective may need to be discontinued. Some mild cases may respond to discontinuance alone. Manage moderate to severe cases with fluid, electrolyte, and protein supplementation, anti-infective therapy active against C. difficile (e.g., oral metronidazole or vancomycin), and surgical evaluation when clinically indicated.
Sensitivity Reactions
Hypersensitivity Reactions
Possible hypersensitivity reactions (e.g., urticaria, pruritus, rash, fever and chills, eosinophilia, joint pain or inflammation, edema, erythema, genital and anal pruritus, angioedema, shock, hypotension, vasodilatation, Stevens-Johnson syndrome, erythema multiforme, toxic epidermal necrolysis, exfoliative dermatitis, anaphylaxis).
If a hypersensitivity reaction occurs, discontinue cephalexin immediately and institute appropriate therapy as indicated (e.g., epinephrine, corticosteroids, maintenance of an adequate airway and oxygen).
Cross-hypersensitivity
Partial cross-sensitivity among cephalosporins and other β-lactam antibiotics, including penicillins and cephamycins.
Prior to initiation of therapy, make careful inquiry concerning previous hypersensitivity reactions to cephalosporins, penicillins, or other drugs. Cautious use recommended in patients with a history of hypersensitivity to penicillins: avoid use in those who have had an immediate-type (anaphylactic) hypersensitivity reaction and administer with caution in those who have had a delayed-type (e.g., rash, fever, eosinophilia) reaction.
General Precautions
History of GI Disease
Cephalosporins should be used with caution in patients with a history of GI disease, particularly colitis. (See Superinfection/Clostridium difficile-associated Diarrhea and Colitis under Cautions.)
Coombs' Test Results
Positive direct Coombs’ test results reported with cephalosporins. This may interfere with certain hematologic studies or transfusion cross-matching procedures. May also cause positive Coombs’ tests in neonates whose mothers received a cephalosporin prior to delivery.
Selection and Use of Anti-infectives
To reduce development of drug-resistant bacteria and maintain effectiveness of cephalexin and other antibacterials, use only for treatment or prevention of infections proven or strongly suspected to be caused by susceptible bacteria.
When selecting or modifying anti-infective therapy, use results of culture and in vitro susceptibility testing. In the absence of such data, consider local epidemiology and susceptibility patterns when selecting anti-infectives for empiric therapy.
Specific Populations
Pregnancy
Category B.
Lactation
Distributed into milk. Use with caution.
Geriatric Use
No overall differences in safety and efficacy in adults ≥65 years of age compared with younger adults, but the possibility of increased sensitivity in some geriatric individuals cannot be ruled out.
Substantially eliminated by kidneys; risk of toxicity may be greater in those with impaired renal function. Select dosage with caution and consider monitoring renal function because of age-related decreases in renal function. (See Renal Impairment under Dosage and Administration.)
Renal Impairment
Decreased clearance and increased plasma half-life.
Use with caution in those with markedly impaired renal function; close clinical observation and appropriate laboratory tests recommended.
Reduced dosage has been recommended in those with Clcr ≤ 40 mL/minute. (See Renal Impairment under Dosage and Administration.)
Common Adverse Effects
Adverse GI effects, including diarrhea, nausea, vomiting, dyspepsia, gastritis, abdominal pain.
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