Phenytoin overdose
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.
Poisonous Ingredient
Diphenylhydantoin
Where Found
Phenytoin is the generic name of drugs such as:
- Cerebyx
- Dilantin
- Dilantin-125
- Phenytek
This list may not be all inclusive.
Symptoms
Symptoms of a phenytoin overdose may include:
-
Coma
Coma
Decreased alertness is a state of reduced awareness and is often a serious condition. A coma is the most severe state of decreased alertness from whi...
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Confusion
Confusion
Confusion is the inability to think as clearly or quickly as you normally do. You may feel disoriented and have difficulty paying attention, remembe...
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Seizures (occasionally)
Seizures
A seizure is the physical changes in behavior that occurs during an episode of specific types of abnormal electrical activity in the brain. The term ...
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- Fever
- Low blood pressure
- Muscle rigidity or spasms
- Sleepiness
- Side-to-side eye movement (nystagmus)
(nystagmus)
Nystagmus is a term to describe uncontrollable movements of the eyes that may be:Side to side (horizontal nystagmus)Up and down (vertical nystagmus)R...
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- Swollen gums
- Tremor (unintentional trembling)
-
Unsteadiness
Unsteadiness
Walking abnormalities can be caused by many different types of problems. Problems with the joints, (such as arthritis), bones (such as deformities),...
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Before Calling Emergency
The following information is helpful for emergency assistance:
- The person's age, weight, and condition
- Name of 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
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.
Poison control center
For a POISON EMERGENCY call:1-800-222-1222ANYWHERE IN THE UNITED STATESThis national hotline number will let you talk to experts in poisoning. This ...
Read Article Now Book Mark ArticleThis 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 pill container with you to the hospital, 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 (computerized axial tomography) scan
- ECG (electrocardiogram, 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 (see above).
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.
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.
Aronson JK. Phenytoin and fosphenytoin. In: Aronson JK, ed. Meyler's Side Effects of Drugs. 16th ed. Waltham, MA: Elsevier; 2016:709-718.
Koch R, Sun C, Minns A, Clark RF. Overdose of cardiotoxic drugs. In: Brown DL, ed. Cardiac Intensive Care. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 34.
Maciel CB, Elie-Turenne MC. Seizures. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 88.
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