At low daily doses (an average of 3-5 mg) haloperidol, usually, well tolerated, side effects are not expressed. At higher doses, side effects develop more often. The most frequent reactions are from the nervous system: From the side of the central nervous system: extrapyramidal disorders of varying severity. Most patients have transient akineto-rigid syndrome, oculogic crises, akathisia, dystonic phenomena.
Perhaps the development of neuroleptic malignant syndrome (NZS), one of the first signs of which is an increase in body temperature.
The state of anxiety, anxiety, agitation, depression, seizures of epilepsy, the development of a paradoxical reaction - exacerbation of psychotic disorders.
With long-term administration of haloperidol, it is possible to develop late dyskinesias, especially in elderly patients and patients with organic deficiency of the central nervous system, so doses for this category of patients should be reduced.
At the beginning of therapy, there may be lethargy, drowsiness or insomnia, headache that occurs after the appointment of correctors (anti-Parkinsonian drugs).
From the cardiovascular system: arrhythmia, tachycardia, when using high doses - lowering blood pressure; orthostatic hypotension, lability of blood pressure, very rarely ECG changes (prolongation of QT interval, signs of flutter and ventricular fibrillation at high doses and in case of predisposition).
From the organs of blood and blood: Transient leukopenia or leukocytosis. erythropenia, lymphomonocytosis, rarely - agranulocytosis.
From the side of the liver: increased activity of "liver" transaminases, jaundice.
From the skin: allergic reactions, rash, toxicodermia, dry skin. photosensitization. hyperfunction of the sebaceous glands.
From the digestive tract: anorexia, dyspepsia, dry mouth, sometimes hypersalivation, nausea. vomiting. constipation. diarrhea.
From the endocrine system: dysmenorrhea, frigidity, gynecomastia, pain in the mammary glands, galactorrhea, impotence, increased libido, priapism, weight gain.
From the genitourinary system: retention of urine (for example, with hyperplasia of the prostate gland), peripheral edema.
Other: increased fatigue, decreased thirst, heat stroke, alopecia, hyponatremia, hyper- or hypoglycemia.