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Drug Class: Commonly Known As: Category:
Anticonvulsant Dilantin® Children, Adult

Phenytoin - What is it for

Phenytoin is used to control seizures and other problems related to the central nervous system.

Phenytoin - Side Effects, Precautions, and Contraindications

What side effects can Phenytoin cause?

Phenytoin may cause some unwanted side effects. Generally, the common side effects tend to occur at the beginning of treatment. Such side effects may include:

Short-term side effects:

  • Drowsiness, dizziness, headache, tiredness, insomnia or fatigue. Be careful when you are giving your child over-the-counter medicines. Medicines for cold and allergy may add on to the drowsiness. Be sure to supervise your child when he/she is involved in activities such as cycling or swimming.

Inform your doctor if any of the above side effects lasts for more than a few days or if they become serious or bothersome.

Long-term side effects:

  • Increase hair growth, enlarged lips, coarsening of facial features

  • Swelling and irritation of the gums. Proper dental care and hygiene may prevent this side effect.

If your child experience excessive drowsiness, nausea and vomiting, doubled vision and unstable movement, slurred speech, confusion, please consult your child’s neurologist as he/she may be too sensitive to phenytoin and may need to adjust his/her dose.

Rare but serious side effects may manifest as the following symptoms. Contact your doctor as soon as possible if you notice any of the following:

  • Severe skin rash, itchy or peeling skin

  • Sudden decrease in urination or dark urine

  • Any unusual signs of bleeding or bruising, prolonged fever, sore throat and mouth sores

  • Yellowing of skin or eyes

Inform your doctor if you notice any other unusual symptoms in your child. Always discuss with your doctor or pharmacist if your child has any problems or difficulties during or after taking phenytoin.

Before taking Phenytoin, what precautions must I follow?

What food or medicine must I avoid when I take Phenytoin?

Phenytoin - Dosage and How to Use

How should Phenytoin be used?

Phenytoin is usually taken 2 times a day. The doctor may start your child on a low dose and then slowly increase the dose. Follow the instructions on the label carefully and ask your pharmacist or doctor if you are unsure.

Do not take this medication more often than directed and do not stop unless instructed by your doctor. Stopping this medicine too rapidly can increase the risk of seizures or fits.

Do not change brands or dosage forms without informing your doctor.

Phenytoin should be taken with or after food and preferably at the same time each day. Antacids and supplements should be spaced apart from phenytoin by 2 hours.

Oral Liquid/Syrups

  • ​Shake well before using. Use a medicine spoon ​or graduated syringe to measure the medicine. Do not use household spoons, as they may not be accurate.​


  • Swallow capsules whole with a glass of water. Do not take capsules that are discoloured.

What should I do if I miss a dose?

Give your child the dose as soon as you remember and then continue to take it as you normally give. However, if it is almost time for the next dose, skip the dose you missed and give the next dose at the usual time.

Do not double or increase the dose.

If your child has missed more than one dose or you are not sure of what to do, consult your doctor or pharmacist.

If your child has less than two weeks medication supplies, please ensure that you have made an appointment with your child’s neurologist or made arrangements to collect more medication.

What should I do if I overdose?

Phenytoin - Handling and Storage

How should I handle Phenytoin safely?

How should I store Phenytoin?

Keep away from children;#Keep in a cool, dry place, away from direct sunlight;#Store at room temperature;#

How should I dispose of Phenytoin safely?

Phenytoin - Additional Information

Check with your doctor or pharmacist if you want to give any other medicines, supplements or herbal products to your child.

If your child sees another doctor, inform him that your child is taking phenytoin before he prescribes any other medications.

  • Tags: Antacid with Simethicone
  • Updated on Wednesday, October 4, 2017
  • This article is contributed by Department of Pharmacy KK Women's and Children's Hospital

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