Haldol (haloperidol) vs. Thorazine (chlorpromazine): What’s the difference?

  • Haloperidol and chlorpromazine are antipsychotic medications used to treat schizophrenia and acute psychosis.
  • Haloperidol is also used to treat tics and vocal utterances of Tourette’s syndrome.
  • Chlorpromazine is also used to treat the manic phase of bipolar disorder and severe behavioral problems in children. Chlorpromazine is also used to control nausea/vomiting, relieve prolonged hiccups, relieve restlessness/anxiety before surgery, and help treat tetanus.
  • A brand name for haloperidol is Haldol.
  • A brand name for chlorpromazine is Thorazine.
  • Side effects of haloperidol and chlorpromazine that are similar include extrapyramidal effects (sudden, often jerky, involuntary motions of the head, neck, arms, body, or eyes; muscle stiffness, restlessness, Parkinsonism), dizziness, tiredness, nausea, sedation/drowsiness, weight gain, trouble sleeping (insomnia), dry mouth, and constipation.
  • Side effects of haloperidol that are different from chlorpromazine include hyperactivity, erectile dysfunction, menstrual irregularities, swelling of breast tissue in males (gynecomastia), vomiting, and dizziness on standing during the first few weeks of treatment.
  • Side effects of chlorpromazine that are different from haloperidol include blurred vision.
  • Do not stop using haloperidol or chlorpromazine suddenly, or you could have unpleasant withdrawal symptoms.

What is haloperidol? What is chlorpromazine?

Haloperidol is an antipsychotic drug used for treating schizophrenia, acute psychosis, and tics and vocal utterances of Tourette’s syndrome. Haloperidol affects certain neurotransmitters in the brain. Haloperidol blocks receptors for the neurotransmitters (specifically the dopamine and serotonin type 2 receptors) on the nerves, so the nerves are not “activated” by the neurotransmitters released by other nerves.

Chlorpromazine is a phenothiazine antipsychotic used to treat schizophrenia, psychotic disorders, manic phase of bipolar disorder, and severe behavioral problems in children. Chlorpromazine helps a person to think more clearly, feel less nervous, and take part in everyday life. It can reduce aggressive behavior and the desire to hurt oneself/others. It may also help to decrease hallucinations. Chlorpromazine works by helping to restore the balance of certain natural substances in the brain. Chlorpromazine is also used to control nausea/vomiting, relieve prolonged hiccups, relieve restlessness/anxiety before surgery, and help treat tetanus.


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What are the side effects of haloperidol and chlorpromazine?


The most common side effects associated with Haldol are:

  • extrapyramidal effects (sudden, often jerky, involuntary motions of the head, neck, arms, body, or eyes, muscle stiffness, akathisia, Parkinsonism),
  • dizziness,
  • hyperactivity,
  • tiredness, and
  • nausea.

Other important side effects are:

Haldol may cause a condition called “orthostatic hypotension” during the early phase of treatment (first week or two). Orthostatic hypotension causes patients to become dizzy upon arising from a lying or sitting position because of a drop in blood pressure.

Haldol also may cause abnormal heart beats, sudden death, seizures, decreases in red and white blood cells, and withdrawal symptoms.

Elderly patients with dementia-related psychosis and treated with antipsychotic drugs such as Haldol are at an increased risk of death.


Common side effects of Thorazine (chlorpromazine) include:

Chlorpromazine may cause dependence. You should only stop taking chlorpromazine under direction from your healthcare professional to avoid withdrawal syndrome.

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What is the dosage for haloperidol vs. chlorpromazine?


  • The recommended oral dose for schizophrenia is 0.5-5 mg two or three times daily up to a maximum dose of 30 mg daily. The lactate solution dose is 2-5 mg every 4-8 hours as needed by intramuscular injection. The lactate solution may also be administered by intravenous injection at 1-2 mg every 2-4 hours and titrated to effect. The maximum single injection dose is 50 mg and the maximum daily dose is 500 mg daily. The dose for the decanoate solution is 10-20 times the daily oral dose once monthly by intramuscular injection. The decanoate solution should not be administered intravenously.
  • The recommended dose for treating Tourette’s syndrome is 0.5-5 mg orally two or three times daily.


  • Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.
  • Chlorpromazine oral is taken by mouth.
  • Chlorpromazine injection is injected into a muscle, or given as an infusion into a vein. A healthcare provider will give you this injection.
  • You may be asked to lie down for a short time after you receive a chlorpromazine injection. This medicine can lower your blood pressure and you may feel light-headed after an injection.
  • Your doctor will need to check your progress on a regular basis. Your vision may also need to be checked.
  • This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using chlorpromazine.
  • If you need to have a spinal tap (lumbar puncture) or any type of x-ray scan or MRI of your spinal cord, tell the doctor ahead of time that you are using chlorpromazine.
  • Do not stop using chlorpromazine suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to safely stop using this medicine.
  • Store at room temperature away from moisture, heat, and light.

What drugs interact with haloperidol and chlorpromazine?


Haldol causes sedation, and sedation may be greater if Haldol is taken with alcohol and other drugs that can cause sedation such as the benzodiazepine class of anti-anxiety drugs for example:

The narcotic class of pain medications and its derivatives for example:

The tricyclic class of antidepressants for example:

Some antihistamines for example:

Certain antihypertensive medications for example:

Carbamazepine (Tegretol) may increase the elimination of Haldol, rendering the Haldol less effective. Rifampin (Rifadin) may decrease the elimination of Haldol, increasing the risk of side effects from Haldol.


Chlorpromazine may interact with:

Many other medicines can interact with chlorpromazine. Tell your doctor all medications you use. During pregnancy, chlorpromazine should be used only if prescribed.

Are haloperidol and chlorpromazine safe to use while pregnant or breastfeeding?


  • Neonates exposed to antipsychotics during the 3rd trimester of pregnancy may develop withdrawal symptoms and extrapyramidal symptoms.
  • Haldol is secreted into breast milk. It should not be used while breast feeding.


  • Chlorpromazine may cause side effects in a newborn if the mother takes the medication during pregnancy.
  • Chlorpromazine can pass into breast milk and may harm a nursing baby. Consult your doctor before breastfeeding.

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Medically Reviewed on 7/31/2019



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Some content courtesy of the U.S. Food and Drug Administration