A 5 mg tablet of hapdol is used to treat schizophrenia, a mental illness in which a person exhibits irrational thoughts and actions. A mental illness called schizophrenia causes abnormal thinking, feelings, and behavior in its victims. The 5 mg Hapdol tablet aids in correcting the chemical imbalances in the brain that cause these alterations. It raises the standard of living and improves attitudes and actions. To be effective, it must be taken on a regular basis. Unless instructed to do so by your physician, do not discontinue taking it.