Phenytoin is used to control some types of seizures (commonly known as fits).

What is​​ this medication used for

Phenytoin is used to control some types of seizures (commonly known as fits).


Dosage and H​ow to Use

  • Do not stop taking your medicines without checking with your doctors.
  • If you miss a dose, take the missed dose as soon as you remember. If it is almost time for your next dose, take only the usual dose. Do not double your dose or use extra medicine to make up for the missed dose.
  • Follow the dose given on your medicine label. Do not take more or less of it or take it more often than that instructed by your doctor.
  • You should continue to take your medicines regularly as instructed by your doctor even if you feel well. Stopping your medicines without informing your doctor may cause your condition to become worse quickly.
  • You can take this medicine with or after food.
  • If you need to take antacids together with phenytoin, take it 2 hours before or after you take phenytoin.
  • If you are on tube feeding, you should take phenytoin 2 hours before or after your feeds.


Side Effects, Precautions,​​​ Contraindication

What are the possibl​e side effects of the medicine?

The common side effects of phenytoin include:

  • Drowsiness
  • Dizziness, headache
  • Feeling tired, having difficulty in sleeping

These symptoms may happen but should get better over time. Check with your doctor if any of these symptoms are serious or do not go away.

If you are taking phenytoin for long term use, some of the following side effects might happen:

  • Growing of hair around the face
  • Thickening of the lips, gums that grow bigger in size and become irritated
    • You can prevent this by taking good care of your mouth and gums

If the following serious side effects happen, you should check with your doctor immediately:

  • Slurred speech, feeling confused
  • Having double vision, unstable movement
  • Red skin rash that forms blisters or peels
  • Fever, sore throat or mouth ulcers that do not go away
  • Yellowing of eyes or skin (Jaundice)
  • Bleeding or bruising that cannot be explained
  • Little urination or urine that is dark coloured

How do I k​now if I am allergic to this medicine?

The symptoms of a drug allergy include one or more of the following:

  • Swollen face/eyes/lips
  • Difficulty in breathing
  • Itchy skin rashes over your whole body

If you experience any of these symptoms, you should stop your medicine immediately and see your doctor.

What precautions shou​ld I follow when taking the medicine?

  • You should inform your doctor if you have the following medical conditions before starting on phenytoin: 

    • Heart problems or irregular heartbeats
    • Low albumin (a type of protein) in the blood 

  • Be careful when driving or operating machinery as this medicine may cause drowsiness. Do not take alcohol and other medicines that make you less alert.

  • If you are taking other medicines, phenytoin may affect how they work. Please see your doctor or pharmacist before using any other medicines, including over-the-counter medicines, vitamins and herbal products. Please make sure that the doctor who treats you knows that you are on phenytoin.
  • Phenytoin can decrease the effectiveness of medicines that prevent pregnancy. Check with your doctor about additional or other methods of birth control
  • You must tell your doctor if you are allergic to any other medicines, or if you develop an allergy while taking this medicine.
  • If you are pregnant or planning to get pregnant or are breastfeeding, you should inform your doctor.
  • See your doctor immediately if your seizures get worse or become different after you start using this medicine.​


Handling and​ Storage

  • Keep your medicines in the original container or packaging, tightly closed or sealed in a cool and dry place, away from direct sunlight.
  • Keep the medicine out of reach of children.
  • Throw away all expired medicines.

​​This medicine has been proven to be safe and effective, but it can cause serious injury if a mistake happens while taking it. This means that it is very important for you to know about this medicine and take it exactly as directed.​​

This article answers some common questions about this medicine. It does not contain all the available information. It also does not take the place of talking to your doctor or pharmacist.



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