Haloperidol injection and haloperidol extended-release injection are used to treat schizophrenia (a mental illness that causes disturbed or unusual thinking, loss of interest in life, and strong or inappropriate emotions). Haloperidol injection is also used to control motor tics (uncontrollable need to repeat certain body movements) and verbal tics (uncontrollable need to repeat sounds or words) in people who have Tourette's disorder (condition characterized by motor or verbal tics). Haloperidol is in a class of medications called conventional antipsychotics. It works by decreasing abnormal excitement in the brain.