Discontinue use if allergic reaction occurs. Hypersensitivity to penicillins, cephalosporins, carbapenems or other β-lactams. Overgrowth of non-susceptible organisms due to prolonged use; pseudomembranous colitis. May cause +ve Coombs' test; false +ve ferricyanide test. May affect ability to drive & use machines. Pregnancy & lactation. Childn <3 mth. Cap: Slight interference w/ Cu reduction methods eg, Benedict's/Fehlings, Clinitest. Concurrent treatment w/ potent diuretics eg, frusemide.