A runny nose is caused by colds, allergies or other viral infections. Cephalosporin is an antibiotic, which is mainly used to treat bacterial infections. Because runny nose is caused by virus, not bacterial infection, cephalosporin is not effective in treating runny nose. Nose running with salt water gargle or nasal spray, warm salt water gargle or nasal spray can clean the nasal cavity and reduce the occurrence of runny nose.