Common adverse reactions
The most common adverse reactions of cephalexin (KEFLEX) include diarrhea, nausea, vomiting, dyspepsia, and abdominal pain. [1]
Hypersensitivity reactions (serious)
Cephalexin can cause allergic reactions including rash, urticaria, angioedema, anaphylaxis, erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis. [1]
Clostridioides difficile–associated diarrhea
Cephalexin can be associated with Clostridioides difficile–associated diarrhea. [1]
Hematologic adverse effects
Cephalexin can be associated with Direct Coombs’ test seroconversion. [1] Cephalexin can induce hemolytic anemia in association with treatment; anemia developing during or after cephalexin therapy requires evaluation for drug-induced hemolytic anemia. [1]
Neurologic and other serious adverse effects
Cephalexin can have seizure potential, with increased risk in patients with renal impairment when dose reductions are not performed. [1] Cephalosporins, including cephalexin, can be associated with prolonged prothrombin time. [1]
Key GI and liver-associated adverse effects
In clinical trials, the most frequent adverse reaction was diarrhea. [1] Nausea and vomiting, dyspepsia, gastritis, and abdominal pain have also occurred. [1] Transient hepatitis and cholestatic jaundice have been reported with penicillins and other cephalosporins, including cephalexin. [1]
Drug-associated risks related to treatment duration
Prolonged use of cephalexin can result in drug-resistant bacteria development and overgrowth of nonsusceptible organisms. [1]