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Phenytoin Injection

Generic Name: Phenytoin Injection (FEN i toyn)

Medically reviewed on May 2, 2018.

Warning

  • This medicine may cause an abnormal heartbeat or low blood pressure if given too fast. Sometimes, this has been deadly. Your doctor will watch your heart closely when you get phenytoin injection. Tell your doctor right away if you have a fast, slow, or abnormal heartbeat during or after a dose.

Uses of Phenytoin Injection:

  • It is used to help control certain kinds of seizures.
  • It may be given to you for other reasons. Talk with the doctor.

What do I need to tell my doctor BEFORE I take Phenytoin Injection?

  • If you have an allergy to phenytoin or any other part of phenytoin injection.
  • If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
  • If you are taking delavirdine.
  • If you have had liver problems in the past while taking phenytoin injection.
  • If you have a slow heartbeat, heart block, or other heartbeat that is not normal.

This is not a list of all drugs or health problems that interact with phenytoin injection.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take phenytoin injection with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Phenytoin Injection?

  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how phenytoin injection affects you.
  • Very bad and sometimes deadly skin reactions (Stevens-Johnson syndrome/toxic epidermal necrolysis) have happened with phenytoin injection. People of Asian descent are most likely to get these. Get medical help right away if you have signs like red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in your mouth, throat, nose, or eyes.
  • Patients who take phenytoin injection may be at a greater risk of having thoughts or actions of suicide. The risk may be greater in people who have had these thoughts or actions in the past. Call the doctor right away if signs like low mood (depression), nervousness, restlessness, grouchiness, panic attacks, or changes in mood or actions are new or worse. Call the doctor right away if any thoughts or actions of suicide occur.
  • Lymph node problems like cancer have happened in people taking phenytoin injection. It is not known if phenytoin injection may be the cause. Talk with your doctor if you have swollen glands.
  • Have the level of phenytoin in your blood checked as you have been told by your doctor. If the level is too high, some side effects may happen. This includes a type of brain problem that may not go back to normal. Talk with your doctor.
  • This medicine may cause weak bones. This may happen more often if used for a long time. This may raise the chance of broken bones. Call your doctor right away if you have bone pain.
  • If you have high blood sugar (diabetes), you will need to watch your blood sugar closely. Tell your doctor if you get signs of high blood sugar like confusion, feeling sleepy, more thirst, more hungry, passing urine more often, flushing, fast breathing, or breath that smells like fruit.
  • This medicine may cause tissue damage if the drug leaks from the vein. Tell your nurse if you have any redness, burning, pain, swelling, blisters, skin sores, or leaking of fluid where the drug is going into your body.
  • If you are 65 or older, use phenytoin injection with care. You could have more side effects.
  • Birth control pills and other hormone-based birth control may not work as well to prevent pregnancy. Use some other kind of birth control also like a condom when taking phenytoin injection.
  • This medicine may cause harm to the unborn baby if you take it while you are pregnant. If you are pregnant or you get pregnant while taking phenytoin injection, call your doctor right away.
  • A bleeding problem that can be life-threatening may happen in newborns if you took phenytoin injection during pregnancy. Talk with your doctor.
  • Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

How is this medicine (Phenytoin Injection) best taken?

Use phenytoin injection as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • It is given into a vein for a period of time.
  • Tell all of your health care providers that you take phenytoin injection. This includes your doctors, nurses, pharmacists, and dentists.
  • This medicine interacts with many other drugs. The chance of phenytoin injection's side effects may be raised or how well phenytoin injection works may be lowered. The chance of the other drugs' side effects may also be raised. This may include very bad, life-threatening, or deadly side effects. Check with your doctor and pharmacist to make sure that it is safe for you to take phenytoin injection with all of your other drugs (prescription or OTC, natural products, vitamins).
  • Talk with your doctor before you drink alcohol or use other drugs and natural products that slow your actions.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • This medicine may affect certain lab tests. Tell all of your health care providers and lab workers that you take phenytoin injection.
  • Wear disease medical alert ID (identification).
  • Follow laws about driving with a seizure problem.
  • Do not switch brands or types of phenytoin injection (like tablets, liquid) unless you talk with the doctor. They may not work the same.
  • Take good care of your teeth. See a dentist often.
  • Do not stop taking phenytoin injection all of a sudden without calling your doctor. You may have a greater risk of seizures. If you need to stop this drug, you will want to slowly stop it as ordered by your doctor.

What do I do if I miss a dose?

  • Call your doctor to find out what to do.

See also: Dosage Information (in more detail)

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Trouble walking.
  • Feeling confused.
  • Slurred speech.
  • Swollen or sore gums.
  • Very bad muscle pain.
  • Trouble controlling body movements, twitching, change in balance, trouble swallowing or speaking.
  • If seizures are worse or not the same after starting phenytoin injection.
  • A burning, numbness, or tingling feeling that is not normal.
  • Not able to control eye movements.
  • Shakiness.
  • Fast or slow heartbeat.
  • Very bad dizziness or passing out.
  • Change in skin color to black or purple.
  • A very bad and sometimes deadly effect has happened in people taking drugs for seizures like phenytoin injection. Call your doctor right away if you have swollen glands; fever; rash; chest pain; unable to pass urine or change in the amount of urine passed; or signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • Rarely, certain blood problems have happened with phenytoin injection. This can lead to bleeding problems or infections. Sometimes, these have been deadly. Tell your doctor right away if you have signs of infection like fever, chills, very bad sore throat, ear or sinus pain, cough, more sputum or change in color of sputum, pain with passing urine, mouth sores, or a wound that will not heal. Tell your doctor right away if you have any unexplained bruising or bleeding, or if you feel very tired or weak.
  • This medicine may cause very bad and sometimes deadly heartbeats that are not normal. Call your doctor right away if you have a heartbeat that does not feel normal.

What are some other side effects of Phenytoin Injection?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Dizziness.
  • Feeling sleepy.
  • Headache.
  • Feeling nervous and excitable.
  • Not able to sleep.
  • Hard stools (constipation).
  • Upset stomach or throwing up.
  • Change in taste.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at http://www.fda.gov/medwatch.

See also: Side effects (in more detail)

If OVERDOSE is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out Phenytoin Injection?

  • If you need to store phenytoin injection at home, talk with your doctor, nurse, or pharmacist about how to store it.

Consumer information use

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.
  • Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about phenytoin injection, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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