Health Encyclopedia

Methapyrilene hydrochloride overdose

Definition

Methapyrilene hydrochloride is an uncommon antihistamine found in cold or flu medicines. Methapyrilene hydrochloride overdose occurs when someone accidentally or intentionally takes more than the normal or recommended amount of this medication.

This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an exposure, you should call your local emergency number (such as 911) or the National Poison Control Center at 1-800-222-1222.

Poisonous Ingredient

Methapyrilene hydrochloride

Where Found

Methapyrilene hydrochloride is found in older antihistamine medications. It was removed from the market in 1979 because it was found to contribute to cancer after long-term use.

Symptoms

Bladder and kidneys
- Difficulty urinating
Eyes, ears, nose, and throat
- Dilated pupils
- Dry mouth
- Vision abnormalities (blurry vision)
Nervous system
- Agitation
- Coma
- Delirium
- Disorientation
- Drowsiness
- Excitation
- Hallucinations
- Nervousness
- Tremor
- Unsteadiness
Skin
- Dry skin
- Flushed skin (red)
Heart and blood
- Convulsions
- Low blood pressure
- Rapid heartbeat

Home Treatment

Seek immediate medical help. Do NOT make a person throw up unless told to do so by Poison Control or a health care professional.

Before Calling Emergency

Determine the following information:

Patient's age, weight, and condition
Name of the product (ingredients and strengths, if known)
Time it was swallowed
Amount swallowed

Poison Control, or a local emergency number

The National Poison Control Center (1-800-222-1222) can be called from anywhere in the United States. This national hotline number 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.

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

See: Poison control center - emergency number

What to expect at the emergency room

The health care provider will measure and monitor your vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated as appropriate. You may receive:

Activated charcoal
Fluids by IV
Blood test for the presence of salicylates or acetaminophen in the blood (Note: Cold and flu medications often contain these ingredients. Anyone who has taken an overdose is at risk from poisoning from these ingredients, too.)
Medicine (antidote) to reverse the effect of the poison
Tube through the mouth into the stomach to wash out the stomach (gastric lavage)

Expectations (prognosis)

How well you do depends on the amount of poison swallowed and how quickly treatment is received. The faster you get medical help, the better the chance for recovery.

Few patients actually die from an antihistamine overdose.

Review Date:2/6/2009
Reviewed By:A.D.A.M. Editorial Team: David Zieve, MD, MHA, Greg Juhn, MTPW, David R. Eltz. Previously reviewed by Stephen C. Acosta, MD, Department of Emergency Medicine, Portland VA Medical Center, Portland, OR. Review provided by VeriMed Healthcare Network (2/27/2008).

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