CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.
Very common (10% or more): Extrapyramidal disorder (up to 34%), hyperkinesia (up to 13%), headache (up to 12%)
Common (1% to 10%): Tardive dyskinesia, dystonia, dyskinesia, akathisia, bradykinesia, hypertonia, somnolence, masked facies, tremor, dizziness, parkinsonism/parkinsonian effects
Uncommon (% to 1%): Convulsion, akinesia, cogwheel rigidity, sedation, involuntary muscle contractions, gait disturbance, persistent tardive dyskinesia
Rare (% to %): Motor dysfunction, neuroleptic malignant syndrome, nystagmus
Frequency not reported: Drowsiness, epileptic/grand mal seizure, vertigo, lethargy
Postmarketing reports: Opisthotonos [ Ref ]
Haloperidol use may lead to the development of symptoms that resemble Parkinson's disease, but that are not caused by Parkinson's. These symptoms may include a taut or mask-like expression on the face, drooling, tremors, pill-rolling motions in the hands, cogwheel rigidity (abnormal rigidity in muscles, characterized by jerky movements when the muscle is passively stretched), and a shuffling gait. Taking the anti-Parkinson drugs benztropine mesylate or trihexyphenidyl hydrochloride along with haloperidol help to control these symptoms. Medication to control Parkinsonian-like symptoms may have to be continued after haloperidol is stopped. This is due to different rates of elimination of these drugs from the body.