Phenytoin

Phenytoin treats certain types of seizures. Do not drink alcohol while you take phenytoin. Talk to your doctor about the safe use of alcohol while you are taking this medication.

Phenytoin Overview

Reviewed: September 19, 2012
Updated: 

Phenytoin is a prescription medication used to treat tonic-clonic (grand mal) seizures, complex partial (psychomotor or temporal lobe) seizures, and to prevent and treat seizures during or after brain surgery. Phenytoin belongs to a group of drugs called anticonvulsants, which lower abnormal electrical activity in the brain that causes seizures.

This medication comes in capsule, chewable tablet, and oral liquid forms. Phenytoin can be taken with or without food.

Common side effects of phenytoin include dizziness, confusion, and slurred speech. Alcohol should not be taken with phenytoin. Do not drive or operate machinery until you know how phenytoin will affect you.

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Phenytoin Cautionary Labels

precautionsprecautionsprecautionsprecautionsprecautionsprecautions

Uses of Phenytoin

Phenytoin is a prescription medicine used to treat tonic-clonic (grand mal), complex partial (psychomotor or temporal lobe) seizures, and to prevent and treat seizures that happen during or after brain surgery.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

 

Phenytoin Brand Names

Phenytoin may be found in some form under the following brand names:

Phenytoin Drug Class

Phenytoin is part of the drug class:

Side Effects of Phenytoin

See "Drug Precautions".

Phenytoin may cause other serious side effects including:

  • Softening of your bones (osteomalacia). This can cause broken bones.

Call your healthcare provider right away, if you have any of the symptoms listed above.

The most common side effects of phenytoin include:

  • problems with walking and coordination
  • slurred speech
  • confusion
  • dizziness
  • trouble sleeping
  • nervousness
  • tremor
  • headache
  • nausea
  • vomiting
  • constipation
  • rash

These are not all the possible side effects of phenytoin. For more information, ask your healthcare provider or pharmacist.

Tell your healthcare provider if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

 

Phenytoin Interactions

Tell your healthcare provider about all of the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your healthcare provider if you take:

  • amiodarone (Cordarone, Pacerone)
  • anticoagulants ('blood thinners') such as warfarin (Coumadin, Jantoven)
  • certain other antidepressants including amitriptyline (Elavil), amoxapine, clomipramine (Anafranil), desipramine (Norpramin), doxepin (Sinequan), imipramine (Tofranil), maprotiline, nortriptyline (Pamelor), protriptyline (Vivactil), and trimipramine (Surmontil)
  • chloramphenicol
  • chlordiazepoxide (Librium, in Limbitrol)
  • diazepam (Valium)
  • digoxin (Lanoxin)
  • disulfiram (Antabuse)
  • doxycycline (Doryx, Monodox,Vibramycin, others)
  • fluoxetine (Prozac, Sarafem, in Symbyax)
  • furosemide (Lasix)
  • H2 antagonists such as cimetidine (Tagamet), famotidine (Pepcid), nizatidine (Axid), and ranitidine (Zantac)
  • antacids that contain calcium (Maalox, Mylanta, Tums, others)
  • hormonal contraceptives (birth control pills, patches, rings, or injections)
  • hormone replacement therapy (HRT)
  • isoniazid (in Rifamate, in Rifater)
  • medications for mental illness and nausea
  • other medications for seizures such as carbamazepine (Carbatrol, Equetro, Tegretol), ethosuximide (Zarontin), methsuximide (Celontin), phenobarbital, and valproic acid (Depakon, Depakene, Stavzor)
  • methylphenidate (Daytrana, Concerta, Metadate, Ritalin)
  • molindone (Moban)
  • oral steroids such as dexamethasone (Decadron, Dexone), methylprednisolone (Medrol), prednisolone, and prednisone (Deltasone)
  • paroxetine (Paxil, Pexeva)
  • quinidine
  • reserpine (Serpalan)
  • rifampin (Rimactane, in Rifamate, in Rifater)
  • salicylate pain relievers such as aspirin, choline magnesium trisalicylate, choline salicylate (Arthropan), diflunisal (Dolobid), magnesium salicylate (Doan's, others), and salsalate (Argesic, Disalcid, Salgesic)
  • sucralfate (Carafate)
  • sulfa antibiotics
  • theophylline (Theo-Dur)
  • ticlopidine (Ticlid)
  • tolbutamide
  • trazodone
  • vitamin D

This is not a complete list of phenytoin drug interactions. Ask your healthcare provider or pharmacist for more information.

Phenytoin Precautions

Do not stop taking phenytoin without first talking to your healthcare provider.

Stopping phenytoin suddenly can cause serious problems.

Phenytoin can cause serious side effects including:

1.  Like other antiepileptic drugs, phenytoin may cause suicidal thoughts or actions in a very small number of people, about 1 in 500.

Call a healthcare provider right away if you have any of these symptoms, especially if they are new, worse, or worry you:

  • thoughts about suicide or dying
  • attempts to commit suicide
  • new or worse depression
  • new or worse anxiety
  • feeling agitated or restless
  • panic attacks
  • trouble sleeping (insomnia)
  • new or worse irritability
  • acting aggressive, being angry, or violent
  • acting on dangerous impulses
  • an extreme increase activity and talking (mania)
  • other unusual changes in behavior or mood

Watch for early symptoms of suicidal thoughts and actions:

  • Pay attention to any changes, especially sudden changes, in mood, behaviors, thoughts, or feelings.
  • Keep all follow-up visits with your healthcare provider as scheduled.

Call your healthcare provider between visits as needed, especially if you are worried about symptoms.

Do not stop taking phenytoin without first talking to a healthcare provider.

  • Stopping phenytoin suddenly can cause serious problems. Stopping a seizure medicine suddenly in a patient who has epilepsy can cause seizures that will not stop (status epilepticus).

Suicidal thoughts or actions can be caused by things other than medicines. If you have suicidal thoughts or actions, your healthcare provider may check for other causes.

2.  Phenytoin may harm your unborn baby.
  • If you take phenytoin during pregnancy, your baby is at risk for serious birth defects.
  • Birth defects may occur even in children born to women who are not taking any medicines and do not have other risk factors.
  • If you take phenytoin during pregnancy, your baby is also at risk for bleeding problems right after birth. Your healthcare provider may give you and your baby medicine to prevent this.
  • All women of child-bearing age should talk to their healthcare provider about using other possible treatments instead of phenytoin. If the decision is made to use phenytoin, you should use effective birth control (contraception) unless you are planning to become pregnant.
  • Tell your healthcare provider right away if you become pregnant while taking phenytoin. You and your healthcare provider should decide if you will take phenytoin while you are pregnant.
  • Pregnancy Registry: If you become pregnant while taking phenytoin, talk to your healthcare provider about registering with the North American Antiepileptic Drug Pregnancy Registry. You can enroll in this registry by calling 1-888-233-2334. The purpose of this registry is to collect information about the safety of antiepileptic drugs during pregnancy.
3.  Swollen glands (lymph nodes)
4.  Allergic reactions or serious problems which may affect organs and other parts of your body like the liver or blood cells. You may or may not have a rash with these types of reactions. Symptoms include:
  • swelling of your face, eyes, lips, or tongue
  • trouble swallowing or breathing
  • a skin rash
  • hives
  • fever, swollen glands, or sore throat that do not go away or come and go
  • painful sores in the mouth or around your eyes
  • yellowing of your skin or eyes
  • unusual bruising or bleeding
  • severe fatigue or weakness
  • severe muscle pain
  • frequent infections or an infection that does not go away

Call your healthcare provider right away if you have any of the symptoms listed above.

Do not take phenytoin if you:

Do not drink alcohol while you take phenytoin without first talking to your healthcare provider. Drinking alcohol while taking phenytoin may change your blood levels of phenytoin which can cause serious problems.

Do not drive, operate heavy machinery, or do other dangerous activities until you know how phenytoin affects you. Phenytoin can slow your thinking and motor skills.

Phenytoin Food Interactions

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of phenytoin there are no specific foods that you must exclude from your diet when receiving phenytoin.

Inform MD

Before you take phenytoin, tell your healthcare provider if you:

  • Have or had liver disease
  • Have or had porphyria
  • Have or had diabetes
  • Have or have had depression, mood problems, or suicidal thoughts or behavior
  • Are pregnant or plan to become pregnant.
    • If you become pregnant while taking phenytoin, the level of phenytoin in your blood may decrease, causing your seizures to become worse. Your healthcare provider may change your dose of phenytoin.
  • Are breastfeeding or plan to breastfeed. Phenytoin can pass into breast milk. You and your healthcare provider should decide if you will take phenytoin or breastfeed. You should not do both.

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.

Taking phenytoin with certain other medicines can cause side effects or affect how well they work. Do not start or stop other medicines without talking to your healthcare provider.

Know the medicines you take. Keep a list of them and show it to your healthcare provider and pharmacist when you get a new medicine.

Phenytoin and Pregnancy

See "Drug Precautions".

Tell your doctor if you are pregnant or plan to become pregnant. Phenytoin may harm the unborn baby and could be dangerous to a pregnant woman. You and your doctor will need to decide if the benefits of phenytoin outweigh the risks. If you are taking phenytoin and you become pregnant, call your doctor right away.

 

Phenytoin and Lactation

Tell your doctor if you are breastfeeding. Phenytoin is excreted in human breast milk. 

Phenytoin Usage

  • Take phenytoin exactly as prescribed. Your healthcare provider will tell you how much phenytoin to take.
  • Your healthcare provider may change your dose. Do not change your dose of phenytoin without talking to your healthcare provider.
  • Phenytoin can cause overgrowth of your gums. Brushing and flossing your teeth and seeing a dentist regularly while taking phenytoin can help prevent this.
  • If you take too much phenytoin, call your healthcare provider or local Poison Control Center right away.
  • Do not stop taking phenytoin without first talking to your healthcare provider. Stopping phenytoin suddenly can cause serious problems.

Do not drink alcohol while you take phenytoin without first talking to your healthcare provider. Drinking alcohol while taking phenytoin may change your blood levels of phenytoin which can cause serious problems.

Do not drive, operate heavy machinery, or do other dangerous activities until you know how phenytoin affects you. Phenytoin can slow your thinking and motor skills.

Phenytoin Overdose

If you take too much phenytoin, call your healthcare provider or local Poison Control Center right away.

 

Other Requirements

  • Store phenytoin suspension at room temperature between 68°F to 77°F (20°C to 25°C). Protect from light. Do not freeze.
  • Store phenytoin INFATABS at room temperature between 68°F to 77°F (20°C to 25°C). Protect from moisture.
  • Store phenytoin capsules at room temperature between 68°F to 77°F (20°C to 25°C) in tight, light-resistant containers.
  • Protect from moisture.
  • Keep phenytoin and all medicines out of the reach of children.