Chlorpromazine overdose

Definition

Chlorpromazine is a prescription medicine used to treat psychotic disorders. It may also be used to prevent nausea and vomiting, and for other reasons.

This medicine may also change the metabolism and the effect of other medicines.

Chlorpromazine overdose occurs when someone takes more than the normal or recommended amount of this medicine. This can be by accident or on purpose.

This article is for information only. DO NOT use it to treat or manage an actual overdose. If you or someone you are with overdoses, call your local emergency number (such as 911), or your local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.

Poisonous Ingredient

Chlorpromazine can be poisonous in large amounts.

Where Found

Chlorpromazine is found in chlorpromazine hydrochloride.

Other medicines may also contain chlorpromazine.

Symptoms

Below are symptoms of a chlorpromazine overdose in different parts of the body.

AIRWAYS AND LUNGS

  • No breathing
  • Rapid breathing
  • Shallow breathing

BLADDER AND KIDNEYS

EYES, EARS, NOSE, MOUTH, AND THROAT

  • Blurred vision
  • Difficulty swallowing
  • Drooling
  • Dry mouth
  • Sores on the gums, tongue, or in the throat
  • Stuffy nose
  • Yellow eyes

HEART AND BLOOD

  • High or very low blood pressure
  • Pounding heartbeat
  • Rapid, irregular heartbeat

MUSCLES, BONES AND JOINTS

  • Muscle spasms
  • Rapid, involuntary movements of the face (chewing, blinking, grimaces, and tongue movements)
  • Stiff muscles in the neck or back

NERVOUS SYSTEM

  • Agitation, irritability, confusion
  • Convulsions (seizures)
  • Disorientation, coma (lack of responsiveness)
  • Drowsiness
  • Fever
  • Low body temperature
  • Restlessness linked with repeated foot shuffling, rocking, or pacing (akathisia)
  • Tremor, motor tics that the person cannot control (dystonia) 
  • Uncoordinated movement, slow movement, or shuffling (with long-term use or overuse) 
  • Weakness

REPRODUCTIVE SYSTEM

  • Change in female menstrual pattern

SKIN

STOMACH AND INTESTINES

Home Care

Seek medical help right away. DO NOT make a person throw up unless poison control or a health care provider tells you to do so.

Before Calling Emergency

Have this information ready:

  • The person's age, weight, and condition
  • The name of the medicine and strength, if known
  • When it was swallowed
  • The amount swallowed
  • If the medicine was prescribed for the person

Poison Control

Your local control poison center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This national hotline will let you talk to experts in poisoning. They will give you further instructions.

This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.

What to Expect at the Emergency Room

Take the container with you to the hospital, if possible.

Your health care provider will measure and monitor you vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated.

Tests that may be done include:

  • Blood and urine tests
  • Chest x-ray
  • CT scan (advanced brain imaging)
  • Electrocardiogram (ECG)

Treatment may include:

  • Activated charcoal
  • Breathing support, including oxygen, tube through the mouth into the lungs, and breathing machine (ventilator)
  • Fluids through a vein (IV)
  • Laxative
  • Medicine to reverse the effects of the drug and treat symptoms

Outlook (Prognosis)

Chlorpromazine is fairly safe. Most likely, an overdose will only cause drowsiness and some side effects such as uncontrolled movements of the lips, eyes, head, and neck for a short time. These movements may continue if they are not treated quickly and correctly.

In rare cases, an overdose can cause more serious symptoms. Nervous system symptoms may be permanent. The most serious side effects are usually due to damage to the heart. If heart damage can be stabilized, recovery is likely. Life threatening heart rhythm disturbances may be difficult to treat, and may result in death. Survival past 2 days is usually a good sign.

References

Aronson JK. Chlorpromazine. In: Aronson JK, ed. Meyler's Side Effects of Drugs. 16th ed. Waltham, MA: Elsevier; 2016:274-275.

Monas J, Skolnik AB. Antipsychotics. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 150.

Review Date: 7/1/2023
Reviewed By: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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