Anti-seizurePrescription only

Phenytoin

Tablet, capsule or injection

Quick Summary

Phenytoin stabilises nerve cells in the brain.

Epilepsy
Status epilepticus

Medical Uses

Epilepsy: Some seizure types.
Status epilepticus: As an injection in hospital.

How it's taken

Take at the same times daily; blood tests check levels.

Your doctor decides the right dose for you and how long to take it.

Your doctor decides the right dose for you. Follow their instructions and the label.

Common Side Effects

Gum overgrowth

Good dental care helps.

Unsteadiness

If levels are high.

Hair growth

Sometimes.

Interactions

Many medicines

Including warfarin and birth control pills.

Critical Warnings

Severe skin reactions

Black Box Warning: Stop for blistering rash.

Don't stop suddenly

Can cause seizures.

Thoughts of self-harm

Black Box Warning: Get help immediately: call 112 or Tele-MANAS (14416).

Drowsiness

Don't drive or use machines if it makes you sleepy, and avoid alcohol.

Sources and further reading

Last updated 21 October 2026. For more detail, see these trusted health organisations.

Related Topics

Epilepsy