The most common are hypersensitivity reactions, including skin rashes, urticaria, eosinophilia, fever, reactions resembling serum sickness, and anaphylaxis. There may be a positive response to the Coombs' test although haemolytic anaemia rarely occurs. Neutropenia and thrombocytopenia have occasionally been reported. Agranulocytosis has been associated rarely with some cephalosporins. Bleeding complications related to hypothrombinemia and/or platelet dysfunction have occurred especially with cephalosporins and cephamycins having a n-methylthiotetriazine side chain, including cefamandole, cefbuperazone, cefmenoxime, cefmetazole, cefonicid, cefoperazone, ceforanide, cefotetan, cefpiramide, and latamoxef. The presence of a methylthiadiazolethiol side-chain, as in cefazolin, or a n-methylthiotetriazine ring, as ceftriaxone, might also be associated with such bleeding disorders.