What Is Phenytoin?

Phenytoin is a medicine used to treat conditions like epilepsy. It is often combined with other anti-epileptic medications. The medicine is only available when prescribed. It is an anticonvulsant that works by slowing down the brain impulses that lead to seizures. It also prevents the neurons in your brain from becoming overactive. The medicine comes in various forms. These include chewable tablets, extended-release capsules, and a suspension. A healthcare provider can also give the medicine as an injection.

What Are The Uses of Phenytoin?

The oral capsule is used to treat seizures in epilepsy and other tonic-clonic seizures. But, it doesn’t treat all types of seizures. You must consult your doctor before taking the medicine to treat your seizures. Phenytoin can be administered after or before brain surgery to prevent and treat seizures. It can also be used for treating trigeminal neuralgia. This is a type of nerve pain that affects the face. Sometimes, the medicine can also be given for irregular heartbeats. It is essential to discuss the use of this medicine with your doctor before using it for your condition.


What Are The Side Effects Of Phenytoin?

The common side effects of Phenytoin include slurred speech, abnormal eye movement, confusion, drowsiness, problems with coordination, balance, and muscle movement.
In case of an allergic reaction to the medicine, you may get hives, swelling in the face or throat. Under such conditions, it is advisable to get emergency medical help.
A serious reaction to the drug that affects different parts of the body also requires immediate medical treatment. Symptoms of such a reaction include fever, skin rash, muscle aches, unusual bruising, severe weakness, yellowing of eyes or skin, and swollen glands.

About Yashoda Hospitals



1. Does Phenytoin Cause Gingival Hyperplasia?

Phenytoin can cause gingival hyperplasia. The incidence rate for gingival hyperplasia is 3% to 93%. Almost 50 % of patients who have been on long-term treatment of Phenytoin are prone to developing gingival hyperplasia. This occurs because of the interaction of the drug with fibroblasts. The gingival overgrowth begins in the papillary region.

2. Is Dilantin And Phenytoin The Same?

Yes. Phenytoin is a generic or a non-brand name. But, there are other common brand names for Phenytoin. These include Dilantin, Epantuin, and Phenytek. In the UK, Epanutin is the commonly used name. But, the medicine is also sold as Phenytoin sodium or Phenytoin. It is essential not to confuse the brand name and the medication's generic name while using it, as this may exacerbate the symptoms.

3. How Does Phenytoin Prevent Seizures?

Phenytoin prevents seizures by reducing the abnormal electrical activity in the patient? brain. The drug modulates the repetitive firing of neurons observed in seizures. It inhibits the voltage-gated sodium channels directly. These channels are present in the cell membranes of neurons. Inhibition of these channels delay cellular reactivation and stop the excessive firing of neurons thereby inhibiting seizures. The drug is distributed from the blood to the tissues.

4. How To Adjust Phenytoin Dose Based On Levels?

Dose adjustment is important as a slight change in the dose of Phenytoin can lead to a significant increase in its serum concentration. This can cause acute toxicity. Therapeutic drug monitoring is required to aid in the adjustment of drug dosage. If a patient is already consuming Phenytoin, then a top-up loading dose is needed. This can be calculated by determining the current concentration of Phenytoin in the plasma by using the formula. Top-Up Phenytoin = (20 ?(measured concentration (mg/L)) x 0.7 x weight (kg) Sodium Dose

5. How Does Phenytoin Work In The Body?

Phenytoin is metabolised extensively in the body. It is transformed into an intermediate called arene oxide. This is a reactive intermediate that can cause many adverse reactions of Phenytoin. These include hepatotoxicity and other idiosyncratic reactions. The drug is excreted as inactive metabolites in the patient? bile.

6. Why Is Phenytoin Given At Night?

Phenytoin is commonly administered in the evening or at night. So that by the morning, there is sufficient concentration of the drug in the tissues and blood. This would reduce the risk or chances of a morning epileptic seizure. Phenytoin can be taken twice daily. But, there should be enough gap between the two doses. If one is taken in the morning, then the other should be consumed in the evening.

7. What Does Phenytoin Do To The Brain?

Phenytoin acts on the neurons in the brain. This is important to reduce the seizures associated with conditions like epilepsy. The excessive firing of the neurons or increased electrical activity in the brain increases the incidence of seizures. Phenytoin works by inhibiting the channels in the neurons that can cause excessive electrical activity. Thus, reducing seizures.

8. What Happens If You Take Too Much Phenytoin?

An overdose of Phenytoin can cause side effects like slurred speech, twitching eye movements, loss of balance, nausea, vomiting, muscle stiffness, slow or shallow breathing, fainting, and feeling light-headed. You should immediately consult a doctor if you experience the symptoms of an overdose. You should follow the dosing instructions from your doctor.

9. Do You Take Phenytoin On An Empty Stomach?

Phenytoin can be taken on an empty stomach or with food. But, you must ensure that the way you take the medicine remains the same every day. This is important as consuming Phenytoin with food can change the amount of time required for it to be absorbed by the body. You should not take antacids within 3 hours of consuming Phenytoin.

10. Who Should Not Take Phenytoin?

You should not take the medicine if you are allergic to it. People with liver problems caused by Phenytoin, history of an allergic reaction to ethotoin, mePhenytoin or fosPhenytoin should not take the medicine. Women who are pregnant and experience seizures should not stop taking the medicine without consulting their doctor. Consult our experts at Yashoda Hospitals to get a medical opinion on using Phenytoin.



  • Yes Same as WhatsApp number
  • By clicking on Send, you accept to receive communication from Yashoda Hospitals on email, SMS and Whatsapp.


  • Yes Same as WhatsApp number
  • By clicking on Send, you accept to receive communication from Yashoda Hospitals on email, SMS and Whatsapp.


  • Yes Same as WhatsApp number
  • By clicking on Send, you accept to receive communication from Yashoda Hospitals on email, SMS and Whatsapp.