Health Guide

Phenytoin (By injection)

Phenytoin (FEN-i-toin)

Treats and prevents seizures.

Brand Name(s):

Phenytoin Sodium Novaplus

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. You should not receive this medicine if you had an allergic reaction to phenytoin or similar medicines, or if you are pregnant or have certain heart rhythm problems.

How to Use This Medicine:


  • This medicine is usually given only for a short time when you cannot take oral medicine, such as when you are in the hospital or when you have surgery.
  • A nurse or other health professional will give you this medicine. This medicine is given as a shot into a muscle or into a vein.
  • After your condition improves, your doctor might switch you to an oral medicine that works the same way. Talk to your doctor if you have any concerns about this.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Do not use this medicine together with delavirdine.
  • The list below includes some of the medicines that can interact with phenytoin. There are many other drugs not listed. Make sure your doctor knows the names of all the medicines you use.
  • Tell your doctor if you are using St John's wort, albendazole, amiodarone, aspirin, chlordiazepoxide, cyclosporine, diazepam, diazoxide, digoxin, disulfiram, folic acid, furosemide, isoniazid, methylphenidate, nisoldipine, praziquantel, quinidine, reserpine, rifampin, theophylline, tolbutamide, or vitamin D.
  • Tell your doctor if you are using cancer medicine, birth control pills, medicine to treat an infection (including a sulfa drug, medicine to treat HIV/AIDS, or medicine for a fungus infection), a steroid medicine, medicine to lower cholesterol, medicine to treat depression, a phenothiazine medicine, a blood thinner (such as ticlopidine, warfarin), or stomach medicine.
  • Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine:

  • It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Tell your doctor right away if you become pregnant.
  • Tell your doctor if you are breastfeeding, or if you have kidney disease, liver disease, diabetes, heart disease, low blood pressure, or porphyria.
  • This medicine may cause the following problems:
    • Serious skin reactions (may happen after treatment has stopped)
    • Drug reaction with eosinophilia and systemic symptoms (DRESS), which may damage organs such as the liver, kidney, or heart
    • Liver damage
    • Decreased levels of blood cells, which may cause bleeding or increase your risk for infection
    • Purple glove syndrome, which may damage skin and tissues near the injection site
    • Higher blood sugar levels
  • This medicine may make you dizzy or drowsy. Do not drive or do anything that could be dangerous until you know how this medicine affects you.
  • Tell any doctor or dentist who treats you that you are using this medicine. This medicine may affect certain medical test results.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, or red skin rash
  • Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
  • Fast, slow, or pounding heartbeat, lightheadedness or fainting
  • Fever, chills, cough, sore throat, and body aches
  • Fever, skin rash, or swollen glands in your armpits, neck, or groin
  • Pain, changes in skin color, sores, peeling, or swelling at or near the injection site
  • Severe confusion, problems with balance or walking, slurred speech, tremors
  • Unusual bleeding, bruising, or weakness

If you notice these less serious side effects, talk with your doctor:

  • Dizziness, feeling of constant movement of self or surroundings
  • Mild nausea or vomiting

If you notice other side effects that you think are caused by this medicine, tell your doctor

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

Last Updated: 7/4/2018
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