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Cyproheptadine overdose

Cyproheptadine is a type of medicine called an antihistamine. These medicines are used to relieve allergy symptoms. Cyproheptadine 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.

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Poisonous Ingredient

Cyproheptadine can be harmful in large amounts.

Where Found

Cyproheptadine is an allergy medicine.

Symptoms

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

BLADDER AND KIDNEYS

• Inability to urinate
• Difficulty urinating

EYES, EARS, NOSE, MOUTH, AND THROAT

• Blurred vision
• Dilated (wide) pupils
• Dry mouth
• Ringing in the ears (tinnitus)

HEART AND BLOOD VESSELS

• Rapid heartbeat
• Increased blood pressure

NERVOUS SYSTEM

• Agitation
• Coma (lack of responsiveness)
• Convulsions (seizures)
• Delirium (acute confusion)
• Disorientation, hallucinations
• Drowsiness
• Fever
• Irregular or rapid heartbeat
• Nervousness
• Tremor (shaking)
• Unsteadiness, weakness

SKIN

• Flushed and dry skin

STOMACH AND INTESTINES

• Constipation
• Nausea and vomiting

Before Calling Emergency

Have this information ready:

• The person's age, weight, and condition
• Name of product (ingredients and strength, if known)
• Time it was swallowed
• Amount 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 to the hospital with you, if possible.

Your health care provider will measure and monitor your vital signs, including temperature, pulse, breathing rate, and blood pressure.

Tests that may be done 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
• Fluids through a vein (by IV)
• Medicine to treat symptoms
• Laxative
• Breathing support, including oxygen, tube through the mouth into the lungs, and breathing machine (ventilator)

Outlook (Prognosis)

If the person survives the first 24 hours, survival is likely. Few people actually die from an antihistamine overdose. Very high doses of antihistamines can cause serious heart rhythm disturbances, which may result in death.

References

Aronson JK. Anticholinergic drugs. In: Aronson JK, ed. Meyler's Side Effects of Drugs. 16th ed. Waltham, MA: Elsevier; 2016:534-539.

Hoppe JA, Monte AA. Anticholinergics. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 140.

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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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