Cephalosporins with an N-methylthiotetrazole side-chain can cause bleeding alone or more severely in the presence of an anticoagulant. The
cephalosporins implicated are
cefaclor, cefaloridine, cefalotin, cefamandole, cefazaflur, cefazolin,
cefixime, cefme- noxime, cefmetazole, cefminox, cefonicid, cefoperazone, ceforanide, cefotetan, cefotiam, cefoxitin, cefpiramide, ceftriaxone, and latamoxef.
Severe bleeding events have been seen with some
cephalosporins. As this usually occurs after about 3 days it would seem prudent to monitor the INR at this point and adjust the anticoagulant dose accordingly. If dose alterations are needed further INR monitoring will be required when the cephalosporin is stopped.