acute pancreatitis due to antipsychotic treatment is rare but sometimes causes a fatal adverse effect . some atypical antipsychotic agents , including clozapine , olanzapine , quetiapine , and risperidone , are associated with acute pancreatitis.1,2 ) among them , acute pancreatitis caused by risperidone is the rarest.3,4 ) although most cases of acute pancreatitis due to atypical antipsychotic agents occur within 6 months of starting antipsychotic administration,1 ) we experienced a schizophrenic patient suffering from pancreatitis after more than 6 months of risperidone therapy . a 69-year - old japanese woman was diagnosed with schizophrenia at the age of 30 years and received outpatient care at another mental hospital . her positive symptoms were not prominent , but her cognitive level was so impaired that she could not regulate her appetite and consumed about 2,000 kcal / day in addition to three ordinary meals . she had never smoked , did not drink alcohol , and did not take any illegal drugs . blood tests ( table 1 ) , abdominal ultrasonography , and a computed tomography ( ct ) scan were performed . clinical features were accompanied by laboratory findings of hyperamylasemia ( amylase , 1,191 u / l ) , hyperlipasemia ( lipase , 1,514 u / l ) , and mild liver enzyme elevations . results of the abdominal ultrasonography were positive for gallstones in the gallbladder and distention of the common bile duct . subsequently , the amylase and lipase titers remained high ( 461 u / l and 804 u / l , respectively ) , although alanine and aspartate aminotransferases decreased gradually to normal levels . at this point , we felt that it was safe for her to start taking the risperidone again . two days after starting the risperidone , serum lipase and amylase increased again to 1,275 u / l and 745 u / l , respectively , and ck also increased ( 766 u / l ) . we decided to suspend the risperidone and introduced 10 mg intravenous haloperidol injections once per day . two days after discontinuing the risperidone , the serum amylase decreased ( 605 u / l ) , but the serum lipase level remained elevated ( 1,654 u / l ) . one week after discontinuing the risperidone , the levels of amylase and lipase decreased gradually ( 309 u / l and 542 u / l , respectively ) , and ck dropped to the normal range . as her general clinical condition and biochemical markers were stable , we changed the haloperidol injection to an oral solution of 6 mg / day aripiprazole because her mental condition worsened after stopping the risperidone treatment . her mental status improved with the aripiprazole treatment , and she was discharged without positive laboratory findings . the patient 's monthly blood tests continue to be normal , including amylase , lipase , and blood cell counts . although atypical antipsychotic - induced pancreatitis has been reported in conjunction with hyperglycemia,5 ) the pathophysiological mechanism of these adverse events remains unclear . most antipsychotic - induced pancreatitis occurs within 6 months after administration1 ) ; however , our case developed pancreatitis more than 6 months after the start of risperidone treatment . risperidone is a 5-ht2a antagonist and ameliorates diet - induced necrotic pancreatitis in mice,6 ) and reduced serum pancreatic amylase levels is observed after endoscopic retrograde cholangiopancreatography.7 ) however , there is no evidence of an association between risperidone treatment and acute pancreatitis . a thorough evaluation for pancreatitis , such as alcohol , tumor , and autoimmune causes , gallstones were present , which were due to an adverse effect of risperidone because the two separate risperidone administrations elevated serum amylase and lipase independently . aripiprazole is currently used in such cases , as aripiprazole is thought to have fewer effects on metabolism , including saccharometabolism , than other atypical antipsychotic agents . lifestyle was also a risk factor in this case . thus , it is necessary to monitor pancreatic function in addition to hyperglycemia in such cases .