Phenytoin
About Phenytoin
Phenytoin is a prescription medicine used to control and prevent certain types of seizures. It is primarily prescribed for people who experience generalised tonic-clonic seizures and psychomotor seizures. It is also used to prevent and treat seizures that may happen during or after brain surgery.
To get the most benefit, you must take Phenytoin consistently at the same times every day as directed by your doctor. You can take this medicine with or without food, but it is best to choose one way and stick to it with every dose to keep medicine levels steady in your body. Making healthy lifestyle choices, such as maintaining a regular sleep schedule and avoiding seizure triggers, can also support your treatment.
While taking Phenytoin, you may experience mild side effects like drowsiness, dizziness, or mild gum swelling. However, if you notice severe skin rashes, swollen glands, yellowing of your eyes or skin, or changes in your mood, you must contact your healthcare provider immediately. Regular dental checkups are also important to manage any gum changes that may occur.
Before starting Phenytoin, talk to your doctor if you have a history of liver problems, kidney disease, diabetes, or depression. Do not take this medicine if you have had a severe allergic reaction to it or similar seizure medicines in the past, or if you have a history of liver damage caused by this medication.
This medicine can interact with alcohol, which can change the amount of the drug in your body and increase drowsiness, and smoking may also affect how it works. It can also interact with many other prescription medications, potentially making them less effective or increasing your risk of side effects. If you are pregnant, planning to become pregnant, breastfeeding, or are an older adult, consult your doctor to discuss the risks and benefits before taking Phenytoin.
Uses of Phenytoin
• Management of Epilepsy/Seizures: Phenytoin is primarily used to control various types of seizures in patients with epilepsy, such as complex partial (psychomotor) seizures and tonic-clonic seizures. It helps to reduce the frequency of these seizures.
• Long-term Seizure Management: Phenytoin is often used as part of a long-term strategy for managing epilepsy, allowing individuals to maintain better seizure control over time and improve their quality of life.
• Short-term Prevention of Seizures: Phenytoin is also used to prevent seizures before/during/after brain surgery, as well as following a traumatic brain injury (head injury).
• Managing Trigeminal Neuralgia: Phenytoin may be used to reduce pain episodes in patients with trigeminal neuralgia by stabilizing nerve impulses.
Medicinal Benefits
Phenytoin helps prevent and control seizures by stabilising electrical activity in the brain. The key benefits of Phenytoin include:
- Reduces Seizure Frequency: Helps lower the frequency of seizures by maintaining stable electrical activity in the brain.
- Controls Seizure Severity: May help reduce the severity of seizure episodes, allowing for greater confidence in daily activities.
- Provides Post-Surgical Seizure Protection: Helps protect against seizures that may occur following brain surgery, supporting a safer recovery process.
- Maintains Continuous Seizure Control: When taken regularly, it helps maintain consistent levels of protection against unexpected seizures.
- Supports Daily Independence: By reducing the risk of unpredictable seizure episodes, it may help improve quality of life and support routine daily activities.
Directions for Use
Follow these steps to get the maximum benefit from treatment with Phenytoin safely and effectively:
- Swallow the tablet or capsule whole with a full glass of water. Do not crush, chew, or break it unless specifically instructed by your doctor.
- If you are taking the liquid form, shake the bottle well before each dose and use a marked medical measuring spoon or syringe to get the exact amount.
- Take your dose at the same times every day to keep a constant level of medicine in your bloodstream.
- You can take this medicine with or without food, but be consistent with your choice.
Always follow your doctor's exact instructions regarding how and when to take your medication. Do not change your dose or stop taking it suddenly without consulting your healthcare provider first.
Storage
Side Effects of Phenytoin
Common Side Effects (Usually mild)
- Dizziness or feeling unsteady
- Drowsiness or tiredness
- Nausea, vomiting, or constipation
- Mild swelling or tenderness of the gums
- Trouble sleeping or headache
Serious Side Effects (Consult your doctor right away)
- A severe skin rash, blistering, or peeling skin
- Swollen lymph glands, fever, or sore throat
- Yellowing of your skin or the whites of your eyes (signs of liver damage)
- Unusual bruising, bleeding, or constant fatigue
- New or worsening mood changes, depression, or thoughts of hurting yourself
Drug Warnings
- Do not stop taking this medicine suddenly: Stopping abruptly can trigger severe, continuous seizures. Any reduction in your dose must be done under your doctor's close supervision.
- Get regular blood tests: Your doctor will need to check your blood regularly to ensure the medicine stays within a safe and effective range.
- Be careful when driving: This medicine can cause drowsiness and dizziness. Avoid driving or operating machinery until you know exactly how it affects you.
- Check for skin changes: Watch closely for any new skin rashes, especially during the first few weeks of treatment, and report them to your doctor immediately.
- Alert other healthcare providers: Always tell your dentist, surgeon, and any other doctors you see that you are taking Phenytoin, as it can affect other treatments and surgeries.
Drug Interactions
Drug-Drug Interactions
Inform your doctor if you are taking any of the following medicines, as they may interact with Phenytoin:
- Antacids and calcium supplements: Can reduce the absorption of Phenytoin if taken at the same time. Space them at least 2 hours apart.
- Blood thinners (like warfarin): Phenytoin can change how these medicines work, increasing the risk of bleeding or blood clots.
- Birth control pills: This medicine can make hormonal contraceptives less effective, increasing the risk of unplanned pregnancy.
- Other seizure medicines: Can unpredictably raise or lower the level of Phenytoin in your body.
Drug-Food Interactions
- Enteral feeds (tube feeding): Can significantly lower the absorption of Phenytoin. Feedings should be paused for a period before and after taking this medicine as directed by your healthcare team.
Drug-Disease Interactions
Inform your doctor if you have a history of the following conditions before taking Phenytoin, as it may worsen your condition or require closer monitoring:
- Liver disease: Your body breaks down this medicine through the liver. If you have liver damage, the drug can build up to dangerous levels.
- Diabetes: This medicine may raise your blood sugar levels, requiring adjustments to your diabetes medications.
- Porphyria: Do not take this medicine if you have this rare metabolic disorder, as it can worsen the condition.
Drug-Drug Interactions Checker List:
Safety Advice
Alcohol
unsafeAvoid alcohol consumption while taking Phenytoin, as it may increase/decrease your blood levels of this medication and cause unpleasant side effects.
Pregnancy
cautionDo not take Phenytoin if you are pregnant unless prescribed by the doctor. Your doctor will prescribe Phenytoin only if the benefits outweigh the risks. If you become pregnant while taking Phenytoin, then do not stop taking Phenytoin without consulting your doctor.
Breast Feeding
cautionPlease consult your doctor before taking Phenytoin if you are breastfeeding. Your doctor will decide whether Phenytoin can be given to breastfeeding mothers or not.
Driving
unsafePhenytoin may cause dizziness and drowsiness. Therefore, avoid driving and operating machinery until you are mentally alert.
Liver
cautionDose adjustment may be needed. Phenytoin should be used with caution in patients with liver impairment/liver disease. Please consult your doctor if you have liver impairment or any concerns regarding this.
Kidney
cautionDose adjustment may be needed. Phenytoin should be used with caution in patients with kidney impairment/kidney disease. Please consult your doctor if you have kidney impairment or any concerns regarding this.
Children
safe if prescribedPhenytoin should be given to children only if prescribed by a doctor.
Habit Forming
Diet & Lifestyle Advise
- Practice excellent oral hygiene: Because this medicine can cause gum swelling, brush your teeth at least twice a day, floss daily, and visit your dentist regularly to keep your gums healthy.
- Get adequate sleep: Lack of sleep is a well-known seizure trigger. Aim for 7 to 9 hours of quality sleep every night to support your treatment plan.
- Monitor your vitamin levels: This medication can sometimes lower your body's levels of calcium and vitamin D. Ask your doctor if you should eat more calcium-rich foods like yoghurt and leafy greens, or if you need a supplement.
- Limit or avoid alcohol: Drinking alcohol can unpredictably change the levels of this medicine in your blood, increasing your risk of seizures or severe side effects like extreme drowsiness.
Special Advise
- Your doctor may advise you to get regular blood tests to check for any abnormalities in your blood and test the amount of Phenytoin in your blood.
Patients Concern
Disease/Condition Glossary
Epilepsy/Seizures: Seizures, also known as fits or convulsions, are a single occurrence of abnormal electrical activity in the brain, whereas epilepsy is a chronic neurological disorder characterised by recurrent seizures. The possible causes of epilepsy include traumatic brain injury, scarring on the brain after a brain injury, high fever, stroke, vascular diseases, lack of oxygen to the brain, brain tumours, and genetic disorders. Symptoms include mood changes, anxiousness, nausea, dizziness, weakness, headache, muscle jerking, spasms, loss of balance, teeth clenching, rapid blinking or eye movements, biting the tongue, confusion, and loss of consciousness.
Trigeminal neuralgia: It is a condition affecting the trigeminal nerve in the face that causes painful sensations similar to electric shock on one side of the face. Symptoms include mild to severe facial pain often triggered by speaking, chewing, or brushing the teeth.
FAQs
Phenytoin is used to treat epilepsy/seizures and prevent seizures during/after brain surgery or after traumatic brain injury. Besides this, Phenytoin may also be used to treat trigeminal neuralgia (facial nerve pain).
Phenytoin contains Phenytoin (an anticonvulsant), which helps prevent neurons from working at a very fast speed, thereby preventing the brain cells from firing together rapidly in an uncontrolled way. As a result, Phenytoin controls the overactivity of the brain cells that cause seizures. Phenytoin slows down the electrical impulses in the nerves and reduces their ability to transmit pain, thereby treating trigeminal neuralgia.
Phenytoin can make birth control pills less effective. Talk to your doctor about using non-hormonal contraceptives like condoms and a diaphragm with spermicide to prevent pregnancy.
Please do not stop taking Phenytoin without consulting your doctor, as it may cause increased seizures. Continue taking Phenytoin for as long as your doctor has prescribed it to you. Do not hesitate to consult your doctor if you experience any difficulties while taking Phenytoin.
Yes, Phenytoin may cause swelling in the gums. Brush and floss your teeth daily; visit your dentist if you experience this problem regularly.
Phenytoin may affect the breakdown of the blood sugar/glucose and may prevent the release of insulin, thereby leading to high blood sugar. So, contact a doctor before using Phenytoin if you have diabetes.
A seizure generally lasts from a few seconds to a few minutes, depending on the type of seizure.
Take Phenytoin with or without food, as advised by your doctor.
You are recommended to avoid alcohol consumption while taking Phenytoin as it may cause increased side effects.
Phenytoin may stay in our system (body) for 5 to 6 days on average. This duration is different for each person. In some cases, it may remain for about 9 to 10 days.
Phenytoin overdose can be fatal and may cause symptoms such as slurred speech, twitching eye movements, muscle stiffness or weakness, tremors, loss of balance, lightheadedness, fainting, vomiting, nausea, and slow or shallow breathing. Also, it may cause very low blood pressure and even coma. Therefore, do not exceed the recommended daily dose.
Patients with liver disease, particularly if they have a history of developing a liver problem due to Phenytoin should avoid taking Phenytoin. Additionally, anyone taking Delavirdine (a medicine used in the treatment of HIV infection) should not take Phenytoin as it may reduce the effectiveness of Delavirdine against HIV and the virus may also develop resistance to Delavirdine. It is advised to inform your doctor before taking Phenytoin if you have any existing heart problem.
You are recommended to consult your doctor before taking Phenytoin with ibuprofen or other medicines to avoid drug interactions.
The most common side effects of Phenytoin in children are overgrowth of the gums and jerky movements of the eyes (nystagmus). In some children, it causes problems with behaviour or thinking, mood change, loss of energy and slow or clumsy movements. High doses may cause side effects such as vomiting, sleepiness and unsteadiness in the feet and hands. To avoid these, the dose is increased gradually. As soon as the dose is reduced, these side effects disappear.
Phenytoin does not cause weight gain. However, on longer term use of a higher dose of Phenytoin, weight loss can occur. If you experience weight gain after taking Phenytoin, please consult your doctor.
Phenytoin can make you feel sleepy as a side effect. However, if you feel extremely sleepy after taking Phenytoin, especially in the first few weeks of treatment or after a dose increase, please consult your doctor.
The common side effects of Phenytoin include weakness, drowsiness, dizziness, confusion, restlessness, slurred speech, constipation, loss of coordination, and abnormal eye movement. Most of these side effects do not require medical attention and will resolve gradually over time. However, you are advised to talk to your doctor if you experience these side effects persistently.
Taking Phenytoin during pregnancy carries risks to the unborn baby, but uncontrolled seizures also pose serious risks. If you are pregnant or planning to become pregnant, do not stop taking your medicine suddenly, but discuss your options with your healthcare provider. Talk to your doctor.
Blood tests are necessary to measure the exact amount of the medicine in your body. This helps your doctor ensure the dose is high enough to prevent seizures but low enough to avoid toxicity. Talk to your doctor.
Take the missed dose as soon as you remember. If your next dose is less than 4 hours away, skip the missed dose and resume your regular schedule; never double your dose. Talk to your doctor.
It may take several days to a few weeks of consistent use for the medicine to reach steady, therapeutic levels in your blood and provide full seizure control. Talk to your doctor.
