Phenytoin overdose
Definition
Phenytoin is a medicine used to treat convulsions and seizures. Phenytoin overdose occurs when someone takes too much of this medicine.
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 the local emergency number (such as 911), or the 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.
Alternative Names
Diphenylhydantoin
Poisonous Ingredient
Diphenylhydantoin
Where Found
Phenytoin is the generic name of medicines such as:
- Cerebyx
- Dilantin
- Dilantin-125
- Phenytek
This list may not be all inclusive.
Symptoms
Symptoms of a phenytoin overdose may include:
- Coma
- Confusion
- Seizures (occasionally)
- Dizziness
- Fever
- Low blood pressure
- Muscle rigidity or spasms
- Sleepiness
- Side-to-side eye movement (nystagmus)
- Slurred speech
- Swollen gums
- Tremor (unintentional trembling)
- Unsteadiness (ataxia)
Before Calling Emergency
The following information is helpful for emergency assistance:
- The person's age, weight, and condition
- The name of the product (as well as the ingredients and strength if known)
- The time it was swallowed
- The amount swallowed
- If the medicine was prescribed for the person
However, DO NOT delay calling for help if this information is not immediately available.
Poison Control
The 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.
You can also get online poison help now at Poisonhelp.org. Just enter the product, poison, or medicine to get expert help.
If you go to the emergency room, take the container for the poison with you, if possible.
What to Expect at the Emergency Room
The health care provider will measure and monitor the person's vital signs, including temperature, pulse, breathing rate, and blood pressure. Blood tests will be done to check phenytoin levels. Symptoms will be treated as appropriate. The person may receive:
- Activated charcoal
- Airway support, including oxygen, breathing tube through the mouth (intubation), and ventilator (breathing machine)
- Blood and urine tests
- Chest x-ray
- CT scan of the head
- Electrocardiogram (ECG), or heart tracing
- Fluids through the vein (intravenous or IV)
- Laxative
- Medicines to treat symptoms
Use of a kidney machine (dialysis) may be used in select cases of severe poisoning with prolonged coma or prolonged incapacitating ataxia.
Outlook (Prognosis)
How well a person does depends on the severity of the overdose and how quickly treatment is received. If there has been prolonged coma, respiratory depression, and shock (damage to multiple internal organs), a more serious outcome is possible.
References
Aronson JK. Phenytoin and fosphenytoin. In: Aronson JK, ed. Meyler's Side Effects of Drugs. 16th ed. Waltham, MA: Elsevier; 2016:709-718.
Meehan TJ. Care of the poisoned patient. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 135.
Nelson LS, Calello DP. Acute poisoning. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 96.
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Review Date:
1/8/2025 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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