It should not be used concomitantly with medications known to prolong the QTc interval (. 5-HT3 antagonists , tricyclic antidepressants , citalopram , etc.) as this may lead to an increased risk of QTc interval prolongation.   Neither should it be given concurrently with lithium (medication) as it may increase the risk of lithium toxicity and neuroleptic malignant syndrome .    It should not be given concurrently with other antipsychotics due to the potential for this to increase the risk of side effects, especially neurological side effects such as neuroleptic malignant syndrome .    It should be avoided in patients on CNS depressants such as opioids, alcohol and barbiturates. 
The influence of renal impairment on the pharmacokinetics of haloperidol has not been evaluated. About one-third of a haloperidol dose is excreted in urine, mostly as metabolites. Less than 3% of administered haloperidol is eliminated unchanged in the urine. Haloperidol metabolites are not considered to make a significant contribution to its activity, although for the reduced metabolite of haloperidol, back-conversion to haloperidol cannot be fully ruled out. Even though impairment of renal function is not expected to affect haloperidol elimination to a clinically relevant extent, caution is advised in patients with renal impairment, and especially those with severe impairment, due to the long half-life of haloperidol and its reduced metabolite, and the possibility of accumulation (see section ).