PHENYTOIN INFATABS- phenytoin tablet, chewable 
Greenstone LLC


This Medication Guide has been approved by the U.S. Food and Drug AdministrationRevised: 12/2018
Phenytoin Infatabs, Chewable Tablets, USP
What is the most important information I should know about phenytoin?
Do not stop taking phenytoin without first talking to your healthcare provider.
  • Stopping phenytoin suddenly can cause serious problems.
  • Stopping a seizure medicine suddenly can cause you to have seizures more often or seizures that will not stop (status epilepticus).
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 in activity and talking (mania)
  • Other unusual changes in behavior or mood
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.
How can I 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.
Phenytoin can cause a type of serious allergic reaction that may affect different parts of the body such as your liver, kidneys, blood, heart, skin or other parts of your body. These can be very serious and cause death. Call your healthcare provider right away if you have any or all of these symptoms:
  • Fever
  • Rash
  • Swollen lymph glands
  • Swelling of your face, eye, lips, or tongue
  • Trouble swallowing or breathing
  • Sore throat
  • Sores in your mouth
  • Bruise easily
  • Purple or red spots on your skin
  • Increase infections
  • Not wanting to eat (anorexia)
  • Nausea
  • Vomiting
  • Yellowing of the skin and the white part of your eyes (jaundice)
Call your healthcare provider even if the symptoms are mild or if you have been taking phenytoin for an extended period of time. These symptoms can be a sign of a serious allergic reaction.
Phenytoin can cause problems with your heart, including a slow heartbeat. Let your healthcare provider know right away if you have any of these symptoms:
  • dizziness
  • tiredness
  • feeling like your heart is beating slowly or skipping beats
  • chest pain
What is phenytoin?
Phenytoin is a prescription medicine used to treat certain types of seizures called tonic-clonic (grand mal) and psychomotor (temporal lobe) seizures.
Do not take phenytoin if you:
  • Are allergic to phenytoin or any of the ingredients in phenytoin. See the end of this leaflet for a complete list of ingredients in phenytoin.
  • Have had an allergic reaction to CEREBYX (fosphenytoin), PEGANONE (ethotoin), or MESANTOIN (mephenytoin).
  • Have had liver problems from taking phenytoin.
  • Take delavirdine.
Before taking phenytoin, tell your healthcare provider about all of your medical conditions, including if you:
  • Have or have had depression, mood problems, or suicidal thoughts or behavior
  • Have had an allergic reaction to a medicine similar to phenytoin called carboxamides, barbiturates, succinimides, and oxazolidinediones
  • Have or had liver or kidney problems
  • Have or had an enzyme problem called porphyria
  • Have or had high blood sugar (hyperglycemia)
  • Drink alcohol
  • Are pregnant or plan to become pregnant. Phenytoin may harm your unborn baby.
    • If you take phenytoin during pregnancy, your baby is at risk for serious birth defects.
    • 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.
    • 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 you are of childbearing age and are not planning on getting pregnant, you should use effective birth control (contraception) while taking phenytoin.
    • 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.
  • Are breastfeeding or plan to breastfeed. Phenytoin can pass into breast milk. You and your healthcare provider should decide if you will take phenytoin while you are breastfeeding.
Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. These medicines can change the levels of phenytoin in your blood.
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.
How should I take phenytoin?
  • Take phenytoin exactly as your healthcare provider tells you.
  • Your healthcare provider will tell you how much phenytoin to take and when to take it.
  • Your healthcare provider may change your dose if needed. Do not change your dose of phenytoin without talking to your healthcare provider.
  • If your healthcare provider has prescribed DILANTIN (phenytoin) oral suspension, ask your pharmacist for a medicine dropper or medicine cup to help you measure the correct amount of phenytoin. Do not use a household teaspoon. Ask your pharmacist for instructions on how to use the measuring device the right way.
  • Do not stop taking phenytoin without first talking to your healthcare provider. Stopping phenytoin suddenly can cause serious problems.
What should I avoid while taking phenytoin?
  • 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.
What are the possible side effects of phenytoin?
See "What is the most important information I should know about phenytoin?"
Phenytoin may cause other serious side effects including:
  • Liver problems.
  • Low blood count which could increase your chance of getting infections, bruising, bleeding and increased fatigue.
  • Softening of your bones (osteopenia, osteoporosis, and osteomalacia) can cause your bones to break (fractures).
  • High blood sugar (hyperglycemia).
  • High levels of phenytoin in your blood that could cause confusion also known as delirium, psychosis or a more serious condition that affects how your brain works (encephalopathy).
Call your healthcare provider right away, if you have any of the symptoms listed above.
The most common side effects of phenytoin include:
  • Irregular movement of the eye (nystagmus)
  • Problems with movement and balance (ataxia)
  • Slurred speech
  • Decrease in coordination
  • Drowsiness (somnolence)
  • Confusion
Phenytoin can cause overgrowth of your gums. Brushing and flossing your teeth and seeing a dentist regularly while taking phenytoin can help prevent this from happening.
These are not all of the possible side effects of phenytoin.
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
How should I store phenytoin?
  • Store Phenytoin Infatabs at room temperature between 68°F to 77°F (20°C to 25°C).
  • Protect from moisture.
Keep phenytoin and all medicines out of the reach of children.
General information about the safe and effective use of phenytoin.
Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. Do not use phenytoin for a condition for which it was not prescribed. Do not give phenytoin to other people, even if they have the same symptoms that you have. It may harm them. You can ask your pharmacist or healthcare provider for information about phenytoin that is written for health professionals.
What are the ingredients in Phenytoin Infatabs?
Active ingredient:
50 mg phenytoin, USP
Inactive ingredients: D & C yellow No. 10, Aluminum Lake, FD&C yellow No. 6, Aluminum Lake, flavor, saccharin sodium, confectioner's sugar, talc, magnesium stearate, and purified water.


LAB 0524-9.0
For more information about phenytoin, visit or call 1 800 438 1985.

Revised: 3/2022
Document Id: 1a091f70-5a1a-4c53-9930-2e1ee10c667d
Set id: 0c9321ae-cc4d-45f0-87d3-e2a5b4f60fde
Version: 30
Effective Time: 20220330
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