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Phenothiazine overdose

Phenothiazines are medicines used to treat serious mental and emotional disorders, and to reduce nausea. This article discusses an overdose of phenothiazines. Overdose occurs when someone takes more than the normal or recommended amount of a certain substance. 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.

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Poisonous Ingredient

The poisonous ingredient is phenothiazine, which may be found in many medicines.

Where Found

These medicines contain phenothiazine or a medicine that has a similar action:

• Chlorpromazine
• Clozapine
• Fluphenazine
• Haloperidol
• Loxapine
• Molindone
• Perphenazine
• Pimozide
• Prochlorperazine
• Thioridazine
• Thiothixene
• Trifluoperazine
• Promethazine

Other medicines may also contain phenothiazine.

Symptoms

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

AIRWAYS AND LUNGS

• No breathing
• Rapid breathing
• Shallow breathing

BLADDER AND KIDNEYS

• Difficult or slow urination
• Inability to completely empty the bladder (urinary retention)

EYES, EARS, NOSE, MOUTH, AND THROAT

• Blurred vision
• Difficulty swallowing
• Drooling
• Dry mouth
• Nasal congestion
• Small or large pupils
• Sores in the mouth, on the tongue or in the throat
• Yellow eyes (icterus)

HEART AND BLOOD

• Low blood pressure (severe)
• Pounding heartbeat
• Rapid heartbeat

MUSCLES AND JOINTS

• Muscle spasms
• Muscle stiffness
• Rapid, involuntary movements of the face (chewing, blinking, grimaces, and tongue movements)

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

• Changes in menstrual patterns

SKIN

• Rash
• Sun sensitivity, rapid sunburn
• Skin color changes

STOMACH AND INTESTINES

• Constipation
• Loss of appetite
• Nausea

Some of these symptoms may occur, even when the medicine is taken properly.

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.

Before Calling Emergency

Have this information ready:

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

Poison Control

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. 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 provider will measure and monitor your vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated.

Tests may include:

• Blood and urine tests
• Chest x-ray
• CT scan (advanced imaging) of the brain for neurologic symptoms
• 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
• Medicines to treat symptoms

Outlook (Prognosis)

Recovery depends on the amount of damage. Survival past 2 days is usually a good sign. 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.

References

Aronson JK. Neuroleptic drugs. In: Aronson JK, ed. Meyler's Side Effects of Drugs. 16th ed. Waltham, MA: Elsevier; 2016:53-119.

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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