Phenytoin (Dilantin®)

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Phenytoin (FEN-e-toyn) is the generic name for Dilantin® (dye-LAN-tin). This medicine is used to control seizures. Your child may need to take phenytoin for a long time because it controls seizures but does not cure them.

Giving the Medicine

Phenytoin can be given in many different forms. Phenytoin comes in capsules, chewable tablets, and liquid form. Do not switch from one form of phenytoin to another. For example, if your child takes phenytoin chewable tablets, do not change to the capsules without asking your child’s doctor. Talk to your health care provider or pharmacist about what is best for your child. The following are the different forms of phenytoin:

  • Chewable tablet - Ask your pharmacist, nurse or doctor before crushing any medicine. Tablets should be chewed very well before they are swallowed. Chewable tablets may be chewed, dissolved in liquid, or swallowed whole.
  • Capsule - Capsules should be swallowed whole, never chewed.
  • Liquid - Shake this medicine before measuring the dose. Use a pediatric measuring device (available at the pharmacy) or a measuring spoon to measure the exact dose. Do not measure liquid medicines in kitchen spoons.

Important to Remember

  • Do not stop giving this medicine or change the amount given without first talking with your child's doctor. Stopping this medicine may cause sudden and severe seizures to occur.
  • For best seizure control, at the same time each day.
  • This medicine can be given with or without food.
  • Read the label each time before you give this medicine.
  • If the medicine is a liquid, use a pediatric measuring device to measure the exact dose (available at the pharmacy). Do not measure liquid medicines in kitchen spoons.
  • Give the exact amount of medicine as ordered by your doctor.
  • Stay with your child until they have swallowed the dose of medicine.

If You Forget to Give a Dose

If you miss a dose of this medicine, give it as soon as you remember. If it is almost time for the next dose, do not give the missed dose at all and do not double the next dose. Instead, go back to your regular dosing schedule. If you have any questions about this, check with your child's doctor or pharmacist.

If a Dose Is Vomited

  • If your child gags or chokes and spits out the dose before swallowing it, let the child calm down and then give the same amount once more.
  • If the medicine is thrown up (vomited) right after you give it, wait 10 to 20 minutes then give the same amount one more time. If the vomiting continues, call your doctor.

Food and Drug Interactions

  • Do not give this medicine at the same time as you give special tube feeding products such as Ensure® or Osmolite®. If your child receives tube feedings with such a product, give the phenytoin at least 1 hour before or 2 hours after feeding.
  • If your child receives continuous tube feedings, stop the tube feedings for 1 hour before giving the medicine. Wait 1 to 2 hours before starting the tube feeding again.
  • Using phenytoin for a long time may decrease the amount of vitamin D in your child’s body. Your child may need to eat more foods high in vitamin D (milk, eggs, fish) as instructed by their doctor.
  • Some cold medicines and cough syrups contain alcohol. Do not give non-prescription medicines (such as acetaminophen, aspirin, antacids or cold medicines) without checking with your child's doctor first.
  • If your child is taking any other medicine, tell your doctor and pharmacist. Certain medicines should not be given with phenytoin.

Possible Side Effects

  • Dizziness
  • Slurred speech
  • Low blood counts
  • Excess body hair
  • Headache
  • Vomiting
  • Unable to sleep
  • Nausea (upset stomach)
  • Confusion
  • Drowsiness
  • Feeling unsteady
  • Changes in the gums around the teeth (gums appear red and swollen)

What to Do About Side Effects

  • Give the medicine with meals or just after eating to reduce nausea. Do it the same way with every dose.
  • To lessen swollen gums, your child should brush and floss their teeth and gums regularly. Use a toothbrush with soft bristles. Hard bristles may hurt the gums. See the dentist regularly.


Different brands of this medicine are absorbed by the body in different ways. If your child has been taking a certain brand of phenytoin, make sure the prescriptions are always filled with the same brand.

When to Call the Doctor

Parent and child with pharmacist at pharmacy counter

If your child is having any side effects that continue or are very bothersome, call the doctor.

  • Constant dizziness, drowsiness, or blurred vision
  • Headache, sleeplessness, or slurred speech that lasts more than 2 days.
  • More seizures than before, or they get worse
  • Trouble walking
  • If pregnancy occurs.


Call for emergency help if your child has any of these signs of an allergic reaction:

  • Trouble breathing
  • Skin rash or hives
  • Fever
  • Unusual bleeding or bruising
  • Severe confusion, unsteadiness, slurred speech
  • Yellow skin or eyes

Medicine storage

  • Store this medicine at room temperature and out of the reach of children.
  • Light and moisture make this medicine less effective. Keep the container tightly capped and store in a dark, dry place (not in the bathroom or above the kitchen sink).
  • Do not use this medicine after the expiration date.
  • Always keep medicine in the labeled container it came in.

Safety Tips and Other Advice

  • Your child should wear a medical identification (ID) bracelet or necklace. If an emergency occurs, the doctor will need to know that your child is taking this medicine.
  • A patient should tell the doctor if she thinks she might be pregnant before she begins taking this medicine. This medicine may cause problems such as birth defects if taken during pregnancy.
  • If your child gets dizzy or drowsy, they should not ride a bike or motor bike, climb trees or use machinery, such as a lawn mower or tractor.
  • The doctor has prescribed this medicine only for your child. Do not give it to anyone else.
  • Tell your child's teacher, school nurse, school coach, baby sitter and others your child is taking this medicine. Tell them what side effects to watch for.
  • Bring all your child's medicines with you (in the original containers) whenever your child sees a doctor, goes to an emergency room or is admitted to the hospital. This helps doctors who may not know your child. Make sure any doctor who treats your child knows they are taking phenytoin.
  • If your child takes too much of this medicine, or if someone else takes this medicine, first call the Central Ohio Poison Center at 1-800-222-1222 (TTY 614-228-2272). They will tell you what to do.
  • When the medicine is no longer needed, dissolve the leftover medicine in water or rubbing alcohol. Mix the dissolved medicine with an unwanted material, like coffee grounds, and place the mixture back in the pill container or in another container that will not leak. Throw the container away in the trash where children and pets cannot reach it.

Follow-up Appointments

  • Your child should be checked by their doctor on a regular schedule to make sure the medicine is working. Blood may need to be drawn at each visit.
  • Make an appointment with your child's dentist. The dentist may want to give your child special dental care. Your child should see the dentist regularly to avoid problems with the gums.
  • Write down all of your questions as you think of them. Bring this list with you when you see the doctor.

Important Phone Numbers

If you have any questions, please call:

Your child's doctor____________________________ phone_____________________

Your pharmacist______________________________ phone_____________________

The Nationwide Children’s Hospital Neurology Clinic at (614) 722-4625.

Phenytoin (Dilantin®) (PDF)

HH-V-13 12/80, Revised 7/19 | Copyright 1980, Nationwide Children’s Hospital