Haldol side effects and drug information

Haldol is a medication that is used to treat psychotic disorders such as schizophrenia, and it can also be used for people with Tourette’s syndrome to control their motor and speech tics.

Formula C21H23ClFNO2
CAS ID 52-86-8
Molar mass 375.9 g/mol
Metabolism Liver-mediated
Excretion Biliary (hence in feces) and in urine
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This drug is not intended to be used for those with dementia-related illnesses as it may escalate the risk of death in the elderly. It should also not be used for those with Parkinson’s disease or those with conditions in the central nervous system.

Before taking this medicine

Before starting with this treatment, inform your doctor if you have the following conditions:

  • Disease in the liver, kidney or heart
  • Thyroid issues
  • Seizure disorder
  • History of QT syndrome
  • Electrolyte imbalance

Also tell your doctor if you are taking other drugs like a blood thinner, or if you are pregnant or planning to become one. Do not take this drug if you are breastfeeding.

Side Effects

Seek medical help if you experience delusions allergic reactions such as having swollen face, throat, lip or tongue, hives, or trouble breathing.

This medicine is not to be used long- term as it can cause serious movement disorder, and the risk is higher in women and the elderly.

If you experience any of these symptoms, see your doctor:

  • Severe nervous system reaction
  • Convulsions
  • Headache with chest pain and severe dizziness
  • Shortness of breath or stabbing chest pain
  • Flu-like symptoms
  • Difficulty in breathing or swallowing
  • Uncontrollable movements of the arms, legs, tongue, face, eyes, lips
  • Sudden mood change, hallucinations, agitation

Its common side effects are:

  • Headache, drowsiness, dizziness
  • Restlessness, tremors
  • Speech problems, stiffness in the muscles
  • Insomnia
  • Overactive reflexes
  • Irregular menstrual cycles, breast enlargement

Indication and Dosage

Dosage may vary depending on the patient and is usually based on the patient’s needs as well as his or her response to the drug. Adjustments of dosages may be given to achieve the most favorable therapeutic response.

For the initial dosage of the treatment, several factors are considered, such as the patient’s age, the severity of the condition, the patient’s response to other antipsychotic drugs, etc.  

For the elderly or those who are weak, or those who have a history of having adverse reactions to other antipsychotic drugs, a lower dosage may be more effective.

For schizophrenic patients with moderately severe to highly severe symptoms, a 2 to 5mg dosage administered intramuscularly is quickly given. Subsequent dosages may be administered, ranging from every hour to every 4 to 8-hour intervals depending on the patient’s response. The maximum allowed dosage is 20mg daily.

Switchover Procedure

Oral administration for this medication is the best way to give this medicine instead of through IM, so as soon as the patient can tolerate it, the administration of this medicine should be shifted to the oral form.  

When switching, the initial dosage used through the IM method may be first used in the oral dosage, and the patient must be carefully monitored to assess any clinical signs, including symptoms, side effects, etc.

Depending on the patient’s condition, the first oral dosage may be given between 12 to 24 hours after the last IM dose.

Drug Interaction

Haldol may interact with other drugs, and they can either be pharmacokinetic or pharmacodynamics.

Pharmacodynamics Interactions

There should be caution in the use of Haldol for those who have QT prolongation, and those who are taking medications that are known to prolong QT interval or those that lead to having electrolyte imbalance.

The use of haloperidol may potentially hinder levodopa and other dopamine agents’ antiparkinson effects. And if used alongside anticholinergic drugs and those with antiparkinson agonists, there may be an increase in the fluid pressure in the eye. Therefore great caution of using them together must be highly considered.

This drug may also cause interactions when used with antipsychotic medications as it may enhance CNS depressants.

Pharmacokinetic Interactions

This medication may be metabolized in various ways, which includes the cytochrome P450 enzyme system and glucuronidation. When another medicine suppresses these routes of metabolism, haloperidol concentrations may increase and could lead to unfavorable reactions such as QT prolongation.

In this type of study, haloperidol concentrations increase from mild to moderate when used with other drugs with substrates or inhibitors of CYP3A4 or CYP2D6 isoenzymes.

If the treatment with rifampin or carbamazepine, which are enzyme-inducing drugs together with Haldol lasts for about 1 to 2 weeks, haloperidol plasma level is greatly reduced.

It is necessary that careful monitoring should be performed when this drug is used with enzyme-inducing medications, and Haldol dosage may be reduced, discontinued, or adjusted when needed.

Part of this study showed that sodium valproate did not cause any effect on the plasma concentration of haloperidol.

Information for Patients

People who are taking Haldol should know that this drug may impede physical and/ or mental abilities, so they should avoid driving or using machinery when under this treatment. This medication may also cause additive reactions and hypotension when used with alcohol.

Warnings and Precautions

Haldol should either be used with high caution or, if possible, not at all with people who have conditions such as dementia-related psychosis, QT prolongation, Torsades de Pointes, Tardive Dyskinesia, neuroleptic malignant syndrome, and pregnant women, among others.  

Discontinuation of this medication must be gradual in order to prevent serious side effects that may result in further complications. This is mostly applicable to those who are using this drug as a maintenance medicine. As for those who are only using it for short- term, withdrawal symptoms do not seem to show.

Patients under this treatment should be careful of falling that may lead to fractures or another fall-related injury as this drug, as well as antipsychotic drugs, may cause somnolence, orthostatic hypotension, and motor instability.

Combined use of Haldol and lithium

Combination therapy of Haldol and lithium are not a good match as there have been reports in some patients that encephalopathic syndrome followed by irreversible brain damage has occurred. If using this combination, the patient must be monitored closely, and when symptoms show, discontinue its use.


Bronchopneumonia has also occurred in some patients who have used antipsychotic drugs, including Haldol. If symptoms occur, an alternative treatment may be used instead.

Medication Guide

Use exactly as prescribed and read the guide before taking this drug. It may hinder mental and/ or physical abilities, that’s why activities such as driving should be avoided when under this medication. Alcohol use must also be avoided due to their additive reactions and other side effects.