Keflex Special Precautions

General: Patients should follow carefully so that any side effects or unusual manifestations of drug idiosyncrasy may be detected. If an allergic reaction to cephalexin occurs, the drug should be discontinued and the patient treated with the usual agents (eg, epinephrine or other pressor amines, antihistamines or corticosteroids).
Prolonged use of cephalexin may result in the overgrowth of nonsusceptible organisms. Careful observation of the patient is essential. If superinfection occurs during therapy, appropriate measures should be taken.
Positive direct Coombs' tests have been reported during treatment with the cephalosporin antibiotics. In hematologic studies or in transfusion cross-matching procedure when antiglobulin tests are performed on the minor side or in Coombs' testing of newborns whose mothers have received cephalosporin antibiotics before parturition, it should be recognized that a positive Coombs' test may be due to the drug.
Cephalexin should be administered with caution in the presence of markedly impaired renal function. Under such condition, careful clinical and laboratory studies should be made because safe dosage may be lower than that usually recommended.
Indicated surgical procedures should be performed in conjunction with antibiotic therapy.
As a result of administration of cephalexin, a false-positive reaction for glucose in the urine may occur. This has been observed with Benedict's and Fehling's solutions and also with Clinitest tablets but not with Tes-Tape (Glucose Enzymatic Test Strip, USP, Lilly).
Broad-spectrum antibiotics should be prescribed with caution in individuals with a history of gastrointestinal disease, particularly colitis.
Use in pregnancy: The daily oral administration of cephalexin to rats in doses of 250 or 500 mg/kg prior to and during pregnancy, or to rats and mice during the period of organogenesis only, had no adverse effects on fertility, fetal viability, fetal weight or litter size. Note that the safety of cephalexin during pregnancy in humans has not been established.
Cephalexin showed no enhanced toxicity in weaning and newborn rats as compared with adult animals. Nevertheless, because the studies in humans cannot rule out the possibility of harm, cephalexin should be used during pregnancy only if clearly needed.
Use in lactation: The excretion of cephalexin in the milk increased up to 4 hrs after a 500-mg dose: The drug reached a maximum level of 4 mg/L, then decreased gradually, and had disappeared 8 hrs after administration. Caution should be exercised when cephalexin is administered to a nursing woman.