Disclosed is an antibody or a binding fragment thereof that binds to risperidone, which can be used to detect risperidone in a sample such as in a competitive immunoassay method. The antibody or fragment thereof can be used in a lateral flow assay device for point-of-care detection of risperidone, including multiplex detection of aripiprazole, quetiapine, olanzapine, and risperidone in a single lateral flow assay device.