###Human: How long is Risperidone effective? ###Assistant: Hi. Since you have taken Risperidone for four years, the brain circuits and its neurotransmitters had been under control. The medicine though it might have been washed out from your body, the effect of it remains for a few weeks to months and your brain circuits may start functioning abnormally after few months and once your symptoms come up again, the dose at which you were taking may not be sufficient to control the symptoms later. So, I advise you to immediately restart medications and do regular follow up with the doctor.