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Medications and Drugs

Brand Names: Cerebyx

Generic Name: fosphenytoin (Pronunciation: fos FEN i toyn)

What is fosphenytoin (Cerebyx)?

Fosphenytoin is an anti-epileptic drug, also called an anticonvulsant. It works by slowing down impulses in the brain that cause seizures.

Fosphenytoin is used to prevent or control seizures. Fosphenytoin is used only for a short time, such as 5 days, when other forms of phenytoin cannot be given.

Fosphenytoin may also be used for other purposes not listed in this medication guide.

What are the possible side effects of fosphenytoin (Cerebyx)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Tell your caregivers at once if you have any of these serious side effects:

  • severe itching, burning, numbness, or tingly feeling in your groin or other body areas;
  • the first sign of any skin rash, no matter how mild;
  • severe blistering, peeling, and red skin rash;
  • feeling like you might pass out;
  • easy bruising or bleeding, unusual weakness;
  • fever, chills, swollen glands, body aches, flu symptoms;
  • stomach pain, loss of appetite, dark urine, jaundice (yellowing of the skin or eyes);
  • confusion, unusual thoughts or behavior;
  • extreme thirst or hunger, urinating more than usual;
  • tremors, or restless muscle movements in your eyes, tongue, jaw, or neck;
  • slurred speech, loss of balance or coordination; or
  • ringing in your ears.

Less serious side effects may be more likely to occur, such as:

  • dizziness, drowsiness, headache;
  • nausea, dry mouth; or
  • warmth, redness, or tingly feeling under your skin.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is the most important information I should know about fosphenytoin (Cerebyx)?

You should not use this medication if you are allergic to fosphenytoin or phenytoin (Dilantin) or if you have certain heart conditions such as slow heartbeats, heart block, AV block, or Adams-Stokes syndrome (a heart rhythm disorder).

Before receiving fosphenytoin, tell your doctor if you are allergic to any drugs, or if you have heart, kidney, or liver disease, low blood pressure, alcoholism, porphyria, or diabetes.

Fosphenytoin may cause harm to an unborn baby, but having a seizure during pregnancy could harm both the mother and the baby. Do not receive fosphenytoin without telling your doctor if you are pregnant. Seizure control is very important during pregnancy and the benefits of preventing seizures may outweigh any risks posed by using fosphenytoin.

If you have received fosphenytoin during pregnancy, be sure to tell the doctor who delivers your baby about your fosphenytoin use. Both you and the baby may need to receive medications to prevent excessive bleeding during delivery and just after birth.

Avoid drinking alcohol while you are receiving fosphenytoin.

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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