Phenytoin
Phenytoin controls selected seizure types by stabilising electrical activity in the brain. Small changes in exposure can have a large effect, so formulations, interactions and blood levels may need careful review.
Key takeaways
- Phenytoin formulations are not always interchangeable, and blood-level monitoring may be needed after a change.
- It interacts with many medicines and hormonal contraceptives and has important pregnancy considerations.
- A painful or blistering rash, marked unsteadiness, confusion or a prolonged seizure needs urgent assessment.
Listings are for comparison only. Suitability and supply depend on clinician and pharmacy checks, stock, destination rules and prescription requirements.
What Phenytoin is used for
Phenytoin may be used for selected focal seizures and tonic-clonic seizures. It does not treat every seizure type and can worsen some seizure disorders.
How it works
Phenytoin limits repetitive firing of nerve cells by stabilising sodium channels. Its processing by the body is nonlinear, which contributes to the need for cautious adjustment.
Important safety checks
Liver function, pregnancy, bone health, oral health and interacting medicines require review. Maintain consistent product use unless the treating team directs a switch. Do not stop phenytoin suddenly, as seizures can worsen. New rash should not be dismissed as a routine adjustment effect.
When to seek urgent care
Seek urgent help for a painful or spreading rash, blisters, peeling skin, mouth or eye sores, fever with swollen glands, severe unsteadiness, slurred speech, confusion, yellow skin or eyes, unusual bleeding or a prolonged or repeated seizure.