Concurrent use Cephalexin with nephrotoxic agents such as aminoglycosides, colistin, polymyxin B or vancomycin may increase the risk of nephrotoxicity. Hence, concomitant use of such drugs should be avoided.
Concomitant administration of Cephalexin with oral probenecid may increase Cephalexin serum concentration because probenecid inhibits tubular secretion resulting in less drug secretion and prolong drug serum concentration.