Fosphenytoin treats certain types of seizures. Your blood pressure and heart rhythm will need to be monitored during treatment. Can cause uncontrollable eye movements.

Fosphenytoin Overview


Fosphenytoin is a prescription medication used to control certain types of seizures. It is also used to treat and prevent seizures that may occur during surgery on the brain or nervous system. Fosphenytoin belongs to a group of drugs called anticonvulsants. These work by lowering abnormal electrical activity in the brain that cause seizures. 

This medication comes in an injectable form to be given directly into a vein (IV) or muscle (IM).

Common side effects of fosphenytoin include uncontrollable eye movements and itching. Fosphenytoin can also cause drowsiness and dizziness. Do not drive or operate heavy machinery until you know how fosphenytoin affects you.

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  • Other
  • Epilepsy
  • Seizures
  • Status Epilepticus

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Fosphenytoin Cautionary Labels


Uses of Fosphenytoin

Fosphenytoin is a prescription medication used to control certain types of seizures, known as generalized tonic-clonic seizures. It is also used to treat and prevent seizures that can occur during brain surgery or nervous system. Fosphenytoin can be substituted for another medication, phenytoin, but should only be used short-term and when oral (by mouth) phenytoin is not possible. 

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

Fosphenytoin Brand Names

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

Fosphenytoin Drug Class

Fosphenytoin is part of the drug class:

Fosphenytoin FDA Warning


The rate of intravenous fosphenytoin administration should not exceed 150 mg phenytoin sodium equivalents (PE) per minute because of the risk of severe hypotension and cardiac arrhythmias. Careful cardiac monitoring is needed during and after administering intravenous fosphenytoin. Although the risk of cardiovascular toxicity increases with infusion rates above the recommended infusion rate, these events have also been reported at or below the recommended infusion rate. Reduction in rate of administration or discontinuation of dosing may be needed