May alter cardiac conduction. Life-threatening arrhythmias occurred with therapeutic doses of antipsychotics (avoid use in underlying QT prolongation, in patients taking medicines which prolong QT interval, or cause polymorphic ventricular tachycardia). May cause anticholinergic effects (use with caution in decreased gastrointestinal motility, paralytic ileus, urinary retention, BPH, xerostomia, or visual problems). Relative to other neuroleptics, thiothixene has low potency of cholinergic blockade. Myelosuppression (e.g. leukopenia, agranulocytosis) observed with antipsychotic use (use contraindicated in bone marrow suppression). Antipsychotic use associated with esophageal dysmotility and aspiration (use with caution in risk of pneumonia (e.g. Alzheimer’s disease)). May cause extrapyramidal symptoms, including pseudoparkinsonism, acute dystonic reactions, akathisia, and tardive dyskinesia (risk of these reactions high relative to other neuroleptics)). Risk of dystonia (and possibly other extrapyramidal symptoms) may be greater with increased doses, use of conventional antispychotics, males, and younger patients. Use may be associated with neuroleptic malignant syndrome (risk may be increased in Parkinson’s disease or Lewy body dementia). May cause orthostatic hypotension (use with caution in cerebrovascular disease, cardiovascular disease, hypovolemia, or concurrent medication use which may predispose to hypotension/bradycardia). May be associated with pigmentary retinopathy. May be sedating. Impaired core body temperature regulation may occur. Use with caution in severe cardiovascular disease. Elderly patients with dementia-related psychosis treated with antipsychotics are at increased risk of death compared to placebo. An increased incidence of cerebrovascular adverse events (including fatalities) reported in elderly patients with dementia-related psychosis. Not approved for dementia-related psychosis. Use with caution in narrow-angle glaucoma (may be exacerbated by cholinergic blockade), in hepatic or renal impairment, in myasthenia gravis (may be exacerbated by cholinergic blockade), in Parkinson’s disease (may be more sensitive to adverse effects), in breast cancer or other prolactin-dependent tumors (elevates prolactin levels), in respiratory disease, and in risk of seizures, including patients with history of seizures, head trauma, brain damage, alcoholism, or concurrent therapy with medications which may lower seizure threshold. May mask toxicity of other drugs or conditions (e.g. intestinal obstruction, Reye’s syndrome, brain tumor) due to antiemetic effects.