Haloperidol is a Dopamine family 2 receptor antagonist and blocks negative signalling from dopamine.
It is in the Anti-psychotics family and is used for severe psychosis and behaviour problems.
Haloperidol is used when 2nd generation antipsychotics are uneffective and have a large side effect profile including: extrapyramidal side effects, parkinsons like symptoms, and anhedonia.
Additionally inhibitions of dopamine receptors in the PFC can lead to negative symptoms of schizophrenia. Weight gain and anticholinergic side effects can be seen, as haloperidol is also a mAChR antagonist. (reduced parasympathetic activity)