Chlorpromazine (Thorazine): Uses, Side Effects, Warnings, & More

What Is Chlorpromazine?

Chlorpromazine is a first-generation antipsychotic medication. This medication was available as the brand Thorazine but was discontinued in the United States. The generic version is currently available. Its precise mechanism of action is not entirely known, but it works by affecting the balance of certain chemicals in the brain. Chlorpromazine primarily works by blocking dopamine receptors in the brain to help regulate chemical imbalances associated with mood and behavior.

Chlorpromazine is FDA-approved for certain mental health conditions, including schizophrenia, bipolar disorder, and behavioral problems. It is also FDA-approved for other uses, including treating nausea and vomiting, calming anxiety before surgery, treating tetanus, and treating acute intermittent porphyria. This article will focus on the mental health conditions that chlorpromazine is used to treat.

FDA approval means that chlorpromazine has undergone an evaluation and has been determined to be safe and effective for its intended use. Chlorpromazine brand name has been discontinued in the United States, but its generic, chlorpromazine, is still available.^1,2

How Does Chlorpromazine Work?

Chlorpromazine is thought to help improve symptoms associated with bipolar disorder, major depressive disorder, and schizophrenia by primarily blocking dopamine receptors, allowing the chemical to stay active longer. This helps stabilize mood, reduce impulsive behaviors, alleviate sensory experiences, and give an overall calming effect, which can lead to a reduction in bipolar and schizophrenic symptoms.¹

What Is Chlorpromazine Used to Treat?

Chlorpromazine is an FDA-approved medication indicated for psychotic disorders and for the treatment of schizophrenia, bipolar disorder, and severe behavioral problems in children. It is also FDA-approved for other uses, including treating nausea and vomiting, calming anxiety before surgery, treating tetanus, and treating acute intermittent porphyria. This article will focus on the mental health conditions that chlorpromazine is used to treat. FDA approval is granted based on evidence in clinical trials of its benefits for the intended uses.

Chlorpromazine is generally not a first or second-line therapy due to safer and equally effective alternatives. Chlorpromazine is also not recommended in patients with known hypersensitivity to phenothiazines and for patients in comatose states or in the presence of large amounts of central nervous system depressants.¹

Chlorpromazine may also be used off-label for some conditions. “Off-label use” is when a prescriber utilizes medications to treat conditions other than those that the FDA has approved because, in their professional judgment, they believe it may offer a benefit to someone. Due to chlorpromazine’s ability to regulate chemicals in the brain, it may be used off-label for the treatment of delirium, anxiety, insomnia, and migraines.^1,3

Common Side Effects of Chlorpromazine

Chlorpromazine is an antipsychotic with common side effects of drowsiness, dry mouth, stuffy nose, and constipation. Less frequently, patients may experience jaundice, seizures, and muscle stiffness. Reactions will vary by individual, and serious reactions should be reported to a healthcare professional.¹

Common side effects of chlorpromazine include:*¹

• Drowsiness
• Dry mouth
• Stuffy nose
• Motor restlessness
• Constipation

*All medications, including chlorpromazine, can cause side effects which can be mild or serious. This is not a comprehensive list of all possible side effects. You should talk with your doctor and pharmacist about any questions you have and to understand the potential side effects and benefits of any medication.

Serious Side Effects of Chlorpromazine

In rare cases, patients may experience serious adverse effects. Patients should immediately seek urgent care or call 911 if these occur. Chlorpromazine has a black box warning for increased mortality in elderly patients with dementia-related psychosis. Patients should monitor for this and contact a provider if noticed.¹

Serious side effects of chlorpromazine include:*¹

• Seizure
• Trouble breathing
• Jaundice
• Tardive dyskinesia
• Neuroleptic malignant syndrome
• Uncontrolled muscle movements
• Motor and sensory instability, including an increased risk of falls

*All medications, including chlorpromazine, can cause side effects which can be mild or serious. This is not a comprehensive list of all possible side effects. You should talk with your doctor or pharmacist about any questions you have and to understand the potential side effects and benefits of any medication.

Chlorpromazine Warnings & Precautions

Chlorpromazine has been associated with an increased risk of death in elderly patients with dementia-related psychosis. Monitor closely for signs of fatigue, weakness, shortness of breath, cough, and fever, especially during the initial months of treatment and when dosage adjustments are made. A potentially life-threatening condition called Reye’s syndrome can be misdiagnosed due to a commonality of symptoms to that of chlorpromazine.

Providers and pharmacists play a role in monitoring and managing these potential risks to ensure well-being during the course of treatment.

Avoid taking chlorpromazine if you are/have:¹

• Allergic to chlorpromazine or other phenothiazines: Mild photosensitivities are seen along with hives, and swelling of the face, lips, and throat.
• Dementia-related psychosis: There is an increased risk of death in older adults.
• Signs and symptoms of Reye’s syndrome: Signs and symptoms of chlorpromazine may be confused with the central nervous system signs of the undiagnosed Reye’s syndrome.
• Pregnancy and breastfeeding: There is evidence that chlorpromazine is excreted in the breast milk of nursing mothers. It’s not known if chlorpromazine is safe to use in pregnancy, but infants have been shown to be born with withdrawal symptoms. It’s important to talk to your healthcare professional about the potential benefits and risks of taking chlorpromazine while pregnant.
• On medication that depresses the central nervous system: this can be sedating and increase the risk of falls and have an effect on normal functioning.

Chlorpromazine Dosages for FDA-Approved Treatment

All chlorpromazine dosage forms have been precisely established clinically, so it is important to monitor and have the prescriber adjust the dose until symptoms are controlled. Many factors affect dosages for individuals, age, type of disorder being treated, and whether a patient is hospitalized or in outpatient treatment.

Chlorpromazine dosage forms and their strengths include tablets ranging from 10-200 mg, oral concentrate in 30 mg/ml and 100 mg/ml strengths, and injection solution in 25 mg/ml and 50 mg/2ml strengths. Patients with acute schizophrenia or manic states take between 500 mg to 2,000 mg a day, while patients who have less severe cases take anywhere from 75 mg to 150 mg a day. Chlorpromazine should not be used in patients younger than 6 months and should be given in lower doses for most elderly patients.¹

Chlorpromazine Forms & Strengths

Chlorpromazine is available as a tablet, oral concentrate, and injection solution, and therapeutic effects last for about 4 to 6 hours. Prescribers may choose one dosage over the other due to the individual needs of the patient. Patients will likely notice the first signs of effectiveness and side effects of chlorpromazine within 1 to 2 weeks and may take up to 4 to 6 weeks to achieve a full therapeutic effect.¹

Chlorpromazine is available in the following forms and strengths:¹

• 10 milligram (mg) tablet
• 25 mg tablet
• 50 mg tablet
• 100 mg tablet
• 200 mg tablet
• 30 milligrams milliliter (mg/ml) oral concentrate
• 100 mg/ml oral concentrate
• 25 mg/ml injection solution

How Should I Take Chlorpromazine?

Chlorpromazine can be taken orally as a tablet or a solution or injected into the muscle or veins. If injected, the site of injection should be clean and dry. If administered into the vein, the solution should be diluted and injected slowly while the patient is lying down. To decrease stomach upset, the oral dose can be administered with water, food, or milk.¹

What Happens If I Miss a Dose of Chlorpromazine?

If you miss a dose of chlorpromazine, use the medication as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time. Do not stop taking chlorpromazine without consulting your prescriber or pharmacist. Withdrawal symptoms are common if therapy is discontinued abruptly, so chlorpromazine should be tapered (decreased slowly) properly.¹

If you have missed a dose and aren’t sure if you should take it, contact your pharmacist or healthcare professional.

Can You Overdose on Chlorpromazine?

Yes, you can overdose on chlorpromazine. Signs and symptoms of an overdose include central nervous system depression (e.g. as severe as coma), low blood pressure symptoms (e.g. dizziness, difficulty breathing, feeling restless), fever, and convulsions. It is crucial to adhere to the prescribed dosage and promptly seek medical attention if any signs of overdose are suspected.

What Should You Do If You Take Too Much Chlorpromazine?

If someone takes too much chlorpromazine or suspects an overdose, seek immediate medical attention. Contacting your healthcare provider, poison control center (800-222-1222), or emergency services (such as 911) is recommended. It’s important to provide information about the dosage and medication taken, the time of ingestion, and other medications taken by the patient.

While waiting for professional assistance, maintain an open airway. Do not attempt to induce vomiting because it may produce involuntary muscle contractions in the head and neck area. Fast and appropriate action is necessary to ensure the patient receives the necessary medical care.¹

What to Avoid When Taking Chlorpromazine

Chlorpromazine can have several dangerous interactions with other medications, substances, and herbs. In combination with other drugs that also make you drowsy, it can worsen the effect and overall sedation. Contact your doctor before using any muscle relaxers, sleeping pills, opioid medications, or medications for anxiety or seizures.

Chlorpromazine may also interact with herbs and supplements such as azo-cranberry and 5-hydroxytryptophan (5-HTP). This is not a comprehensive list. A pharmacist or your healthcare professional will be most helpful in identifying potential drug interactions with chlorpromazine.¹

7 substances you should avoid while taking chlorpromazine include:

• Opioids: Lead to drowsiness and sedation
• Sleeping aids: Lead to drowsiness and sedation
• Antidepressants: Can increase the risk of an irregular heart rhythm
• Anticoagulants: Bleeding risk 
• Antihistamines (e.g Benadryl, Zyrtec): Increased anticholinergic effects (e.g. dryness, dilated pupils, increased heart rate)
• Azo-Cranberry: Increased risk for confusion and drowsiness
• 5-hydroxytryptophan: Worsening schizophrenia symptoms

How to Get a Prescription for Chlorpromazine

Getting a prescription for chlorpromazine requires a doctor’s visit. The doctor writes a prescription and sends it to a patient’s preferred pharmacy. A patient will be evaluated before being prescribed chlorpromazine as a treatment. Finding a psychiatrist may be part of the process if you are looking for a new prescriber.

Questions to Ask Your Healthcare Provider About Chlorpromazine

Individuals may have questions about chlorpromazine when seeing treatment for schizophrenia, bipolar, or behavioral problems, especially when other treatments have been ineffective. Patients should seek to learn about the potential benefits, risks, and side effects of the medication when consulting a doctor, psychiatrist, pharmacist, or therapist.

Discuss your medical history and current medication use with your prescriber if you are considering chlorpromazine as a potential treatment. Concerns about interactions with food and dietary restrictions should also be discussed. Online psychiatry services may be a good option if you need to change prescribers.

Questions to ask your care team about chlorpromazine include:

• How safe is chlorpromazine?
• How long will it take for me to adjust to taking chlorpromazine?
• Am I at risk for more serious side effects with chlorpromazine if I am already taking other medications?
• What is the best dosage of chlorpromazine to ensure fewer side effects?
• What should I do if I am unsure whether antipsychotic medications are right for me?
• How often should I see you for checkups while taking chlorpromazine?
• Does my medical history increase my risk of side effects from chlorpromazine?
• Which medication has the best results as a treatment for bipolar, schizophrenia, or behavior problems?