risperidone has been reported to be effective in management of disruptive behaviors , including hyperactivity , irritability , aggression , and temper tantrums . increased appetite , weight gain , headache , and sedation literature search revealed only four published reports of risperidone - related bleeding , including hemorrhagic cystitis,1 ) nasal bleeding,2,3 ) and gastrointestinal bleeding.4 ) we hereby describe the first pediatric case of gingival bleeding during risperidone treatment . an 11-year - old - girl was referred to our out - patient clinic for her hyperactivity , temper tantrums , sleep problems , and self - injurious behaviors . according to her psychiatric assessment and psychometric evaluation , she was started on risperidone 0.25 mg / day treatment for her disruptive behaviors and two weeks later the dose was increased to 0.5 mg / day . one - week after the dose increase , she experienced gingival bleeding when she brushed her teeth . risperidone was considered to be the reason for bleeding , therefore we decided to reduce the dose to 0.25 mg / day . gingival bleeding ceased within a week . because worsening of her behavioral problems , her mother increased the dose to 0.33 mg / day . she experienced gingival bleeding rarely ( twice a month ) and mildly during this dose regime , therefore we stopped the medication . we decided to change risperidone to methylphenidate ; however , her parents refused to continue to the treatment because of their worries about the potential side effects . she had no history of any bleeding disorder or any other medical condition including current allergies . she was not taking any other medication other than risperidone at the time of the development of bleeding . there are several case reports about risperidone - related bleeding ; however , to our knowledge , there is no report of gingival bleeding associated with risperidone in the literature . we presented a case who experienced gingival bleeding when risperidone dose was increased to 0.5 mg / day , and subsided after decreasing the dose to 0.25 mg / day , suggesting a dose - dependent side - effect . however , the chronological relationship between the time of risperidone 0.5 mg / day administration and emergence of bleeding in the absence of an identifiable medical condition suggests risperidone to be the causative agent . there was no other agent likely to be the cause of bleeding , except risperidone , and bleeding ceased when the dose was decreased . although an etiological relationship between risperidone use and gingival bleeding can not be drawn from a single case , the naranjo probability scale score ( 8) reveals a probable relationship.5 ) the bleeding side effect of risperidone might be caused by several mechanisms , including thrombocytopenia and 5-hydroxytryptamine 2a ( 5-ht2a ) receptor antagonism.3 ) thrombocytopenia is a known adverse effect of atypical antipsychotics and has also been reported during risperidone.6 ) in our reported case platelet count was normal , therefore , gingival bleeding could not be a consequence of thrombocytopenia . antagonism of 5-ht2a receptor was suggested to cause bleeding by inhibiting the release of vasoconstrictors from platelets and reducing the platelet aggregation.4 ) therefore , we may speculate that risperidone s high affinity to 5-ht2a receptors might have probably resulted gingival bleeding . this case suggests that bleeding associated with risperidone may be a dose - dependent side effect . however , these potential explanations may not describe the entire mechanism of this adverse reaction . it is also possible that she might have some undetermined predisposing factors for bleeding that is triggered by risperidone . there are several reports on gingival bleeding during anti - depressants;7 ) however , this is the first case on gingival bleeding associated with risperidone . although bleeding is a rare side effect , clinicians should be aware that risperidone may cause bleeding . risperidone may also increase the risk of bleeding in susceptible patients with a history of coagulation disorders , and with concomitant use of other drugs , including non - steroidal anti - inflammatory drugs , aspirin , or other medications that affect coagulation .
there are several case reports on risperidone - related bleeding ; however , to our knowledge , there is no report about gingival bleeding associated with risperidone in the literature . 
 we presented a case who experienced gingival bleeding when risperidone dose was increased to 0.5 mg / day , and subsided after decreasing the dose to 0.25 mg / day , suggesting a dose - dependent side - effect . 
 the bleeding side effect of risperidone might be caused by several mechanisms , including 5-hydroxytryptamine 2a receptor antagonism . 
 although bleeding associated with risperidone is rarely reported , clinicians should be aware of this side effect .