 [ Symptoms ] can antibiotic cephalexin cause blue veins to appear in forhead i just started taking cephalexin 500mg after minor operation blue veins appeared in my forehead could this be reaction to drug if not is is serious  jmcnich196@aol com [ Disease ] assuming you did not strain or injure your arm i feel that it is related soley to your flu shot i think it important to address this issue with your doctor sometimes the needle used for the injection can cause a hematoma    a pocket of blood at the injection site this can cause an sterile abscess or even an abscess that is secondarily infected get it checked out