Generic name: Phenytoin sodium.

Other brand names: Diphenylan Sodium, Phenytoin Sodium Extended.

Dilantin is an anticonvulsant. It reduces excessive stimulation in the brain. 

Quick Facts About Dilantin


Used to treat grand mal seizures and temporal lobe seizures. Also used to prevent and treat seizures during and after neurosurgery.

Dilantin Dosage

Strictly follow therapy regimen. If using Suspension form, shake well before using; swallow Kapseals whole. Infatabs can be chewed thoroughly and swallowed, or swallowed whole. Infatabs are not for once-a-day dosing. Do not switch brands without advice from your doctor.

  • Usual adult dose: standard daily dose — one 100-milligram capsule 3 times per day. On an ongoing basis, one capsule 3 to 4 times per day is standard. For 1 dose a day — one 300-milligram capsule per day, if your seizures are controlled by three 100-milligram capsules.
  • Usual child dose: 5 milligrams per 2.2 pounds of body weight per day, divided into 2 or 3 equal doses, up to 300 milligrams per day to start. Ongoing dose — 4 to 8 milligrams per 2.2 pounds of body weight.
  • Missed dose: 1 dose per day — take as soon as possible, unless you remember the next day. In that case, do not take missed dose; go back to regular schedule. Alore than 1 dose per day — take as soon as possible, unless within 4 hours of the next dose. In that case, do not take missed dose; go back to regular schedule. If you forget to take this medication for more than 2 days in a row, call your doctor. Do not double doses.

Dilantin Side Effects

Overdose symptoms:

coma, difficulty pronouncing words correctly, involuntary eye. movement, lack of muscle coordination, low blood pressure, nausea, sluggishness, slurred speech, tremors, vomiting. If you suspect an overdose, immediately seek medical attention.

More common side effects: decreased coordination, involuntary eye movement, mental confusion, slurred speech.

Less common Dilantin side effects: abnormal hair growth, abnormal muscle tone, blood disorders, coarsening of facial features, constipation, dizziness, enlargement of lips, fever, headache, inability to fall asleep or stay asleep, joint pain, nausea, nervousness, overgrowth of gum tissue, Peyronie’s disease, rapid and spastic involuntary movement, skin peeling or scaling, skin rash, tremors, twitching, vomiting, yellowing of skin and eyes.


Inform your doctor before combining Dilantin with:

amiodarone anti-arrhythmics such as Cordarone; antacids containing calcium; blood thinners such as Coumadin; carbamazepine (Tegretol); chloramphenicol (Chloromycetin); chlordiazepoxide (Librium); diazepam (Valium); Dicumarol; digitoxin (Crystodigin); disulfiram (Antabuse); doxycydine (Vibramycin); estrogens such as Premarin; ethosuximide (Zarontin); felbamate (Felbatol); furosemide (Lasix); isoniazid (Nydrazid); major tranquilizers such as Mellaril and Thorazine; methylphenidate (Ritalin); molindone hydrochloride (Moban); oral contraceptives; phenobarbital; phenylbutazone (Butazolidin); quinidine (Quinidex); reserpine (Diupres); rifampin (Rifadin); salicylates such as aspirin; steroid drugs such as prednisone; succinimides (anticonvulsant medications); sucralfate (Carafate); sulfonamides; theophylline (Theo-Dur); tolbutamide (Orinase); trazodone (Desyrel); ulcer medications such as Tagamet and Zantac; valproic acid (Depakene). Tricyclic antidepressants (Elavil or Norpramin) may cause seizures.

Avoid alcohol while taking Dilantin. 

Special Cautions

Anti-epileptic medications such as Dilantin can cause birth defects. If pregnant or planning to become pregnant, inform your doctor immediately. Appears in breast milk; could affect a nursing infant.

Seniors should use cautiously, may show signs of drug poisoning.

Follow doctor’s instructions carefully for children.

  • Do not stop Dilantin therapy abruptly, may cause status epilepticus, a possibly fatal condition.
  • If allergic to or sensitive to phenytoin or similar epilepsy medications, do not take Dilantin.
  • Monitor for hyperglycemia (high blood sugar).
  • Should not be used for seizures due to hypoglycemia (low blood sugar) or petit mal seizures.
  • Notify doctor if a skin rash appears (measles-like or scale-like).
  • May be a link between Dilantin therapy and the development of certain lymph system diseases, including Hodgkin’s disease.
  • Use cautiously if you have porphyria (skin disorder).
  • Maintain good dental hygiene during Dilantin therapy.
  • May cause abnormal bone softening due to interference with vitamin D metabolism.


HealthSurvey.org provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Dilantin side effects, please contact your healthcare provider.