In obsessive - compulsive disorder. Which is not given:

Many guides are giving the answer as haloperidol but that is not the right answer here. The American psychiatric association guidelines clearly state that, if patients do not respond to SSRIs and Clomipramine, one of the treatment strategy is augmentation with antipsychotics. The best evidence is for haloperidol, Risperidone, quetiapine and olanzapine. In comparison, Carbamazepine is rarely used in OCD and has very weak evidence in comparison to haloperidol. Hence, the best answer here would be Carbamazepine.