What are effects of haloperidol?

Depends...: Therapeautic effects are decreased paranoia, decreased voices and calming effects. Side effects are sedation, tremor, feelinig flat. So the effect depends on what you are using the Haldol (haloperidol) for and how much of it. Lower doses more often give a treatment effect but you may need higher doses which may be helpful but also cause side effects. Example you may need a high dose for maina.

Antipsychotic : Haloperidol is an antipsychotic medicine that is primarily used for the treatment of schizophrenia but is also used for treatment of tics related to Tourette's syndrome.