What are the side effects of haloperidol (antipsychotic medication)?

From the Guidelines

Haloperidol can cause several side effects, including extrapyramidal symptoms (EPS), tardive dyskinesia, neuroleptic malignant syndrome, and QT prolongation, which can be life-threatening, as reported in a study published in 2018 1.

Common Side Effects

• Drowsiness
• Dry mouth
• Blurred vision
• Constipation
• Dizziness

Serious Side Effects

• Extrapyramidal symptoms (EPS), including muscle stiffness, tremors, restlessness (akathisia), and abnormal involuntary movements, as noted in a study published in 2016 1
• Tardive dyskinesia, characterized by uncontrollable movements of the face and body that can be permanent
• Neuroleptic malignant syndrome, a rare but serious condition with symptoms of high fever, muscle rigidity, and altered mental status requiring immediate medical attention
• QT prolongation, potentially leading to dangerous heart rhythm problems, especially in those with heart conditions or taking other medications that affect heart rhythm, as reported in a study published in 2006 1

Management of Side Effects

• Patients should report any concerning side effects to their healthcare provider, who may adjust the dose or prescribe medications to manage these effects
• Anticholinergics may be used to manage EPS, but their use should be limited to patients with significant EPS, as recommended in a guideline published in 2011 1
• Patients on long-term haloperidol treatment should be monitored for signs of tardive dyskinesia and other side effects, and the medication should be discontinued if possible, as suggested in a study published in 2018 1

From the FDA Drug Label

Tardive Dyskinesia As with all antipsychotic agents, haloperidol has been associated with persistent dyskinesias Tardive dyskinesia, a syndrome consisting of potentially irreversible, involuntary, dyskinetic movements, may appear in some patients on long-term therapy or may occur after drug therapy has been discontinued. Other CNS Effects Insomnia, restlessness, anxiety, euphoria, agitation, drowsiness, depression, lethargy, headache, confusion, vertigo, grand mal seizures, exacerbation of psychotic symptoms including hallucinations and catatonic-like behavioral states which may be responsive to drug withdrawal and/or treatment with anticholinergic drugs Body as a Whole:Neuroleptic malignant syndrome (NMS), hyperpyrexia and heat stroke have been reported with haloperidol. Hematologic Effects:Reports have appeared citing the occurrence of mild and usually transient leukopenia and leukocytosis, minimal decreases in red blood cell counts, anemia, or a tendency toward lymphomonocytosis. Liver Effects:Impaired liver function and/or jaundice have been reported. Dermatologic Reactions:Maculopapular and acneiform skin reactions and isolated cases of photosensitivity and loss of hair. Endocrine Disorders:Lactation, breast engorgement, mastalgia, menstrual irregularities, gynecomastia, impotence, increased libido, hyperglycemia, hypoglycemia and hyponatremia Gastrointestinal Effects:Anorexia, constipation, diarrhea, hypersalivation, dyspepsia, nausea and vomiting. Autonomic Reactions:Dry mouth, blurred vision, urinary retention, diaphoresis and priapism. Respiratory Effects:Laryngospasm, bronchospasm and increased depth of respiration. Special Senses:Cataracts, retinopathy and visual disturbances Post-marketing Events Hyperammonemia has been reported in a 51⁄2 year old child with citrullinemia, an inherited disorder of ammonia excretion, following treatment with haloperidol.

The side effects of haloperidol include:

• CNS effects: insomnia, restlessness, anxiety, euphoria, agitation, drowsiness, depression, lethargy, headache, confusion, vertigo, grand mal seizures
• Tardive dyskinesia: potentially irreversible, involuntary, dyskinetic movements
• Neuroleptic malignant syndrome (NMS): hyperpyrexia, muscle rigidity, altered mental status, and evidence of autonomic instability
• Hematologic effects: leukopenia, leukocytosis, anemia, lymphomonocytosis
• Liver effects: impaired liver function, jaundice
• Dermatologic reactions: maculopapular and acneiform skin reactions, photosensitivity, loss of hair
• Endocrine disorders: lactation, breast engorgement, mastalgia, menstrual irregularities, gynecomastia, impotence, increased libido, hyperglycemia, hypoglycemia, hyponatremia
• Gastrointestinal effects: anorexia, constipation, diarrhea, hypersalivation, dyspepsia, nausea, vomiting
• Autonomic reactions: dry mouth, blurred vision, urinary retention, diaphoresis, priapism
• Respiratory effects: laryngospasm, bronchospasm, increased depth of respiration
• Special senses: cataracts, retinopathy, visual disturbances
• Post-marketing events: hyperammonemia 2

From the Research

Side Effects of Haloperidol

The side effects of haloperidol include:

• Extrapyramidal symptoms (EPS), such as parkinsonism, akathisia, and dystonia 3, 4, 5
• Tardive dyskinesia, a chronic motor problem that can occur with long-term use of haloperidol 3
• Rhabdomyolysis, a rare but serious side effect that can occur without neuroleptic malignant syndrome 6
• Acute movement disorders, which can cause subjective discomfort and distress, and may lead to poor compliance with medication 3

Patient Characteristics and Side Effects

Certain patient characteristics may increase the risk of developing side effects from haloperidol, including:

• Younger age, which may increase the risk of parkinsonism 4
• Higher doses of haloperidol, which may increase the risk of EPS 4
• Combination with other substances, such as marijuana, which may increase the risk of acute dystonia and other side effects 5

Management of Side Effects

Side effects of haloperidol can be managed with various treatments, including:

• Prophylactic antiparkinsonian medication, which can be effective in preventing EPS 4
• Benzodiazepines, such as lorazepam, which can be effective in controlling akathisia 4
• Intramuscular diphenhydramine, which can be effective in resolving acute dystonia 5