About phenytoin
Hydantoin anticonvulsant
Used for
- Prevention and treatment of focal and tonic-clonic seizures
- Prevention of seizures during or after brain surgery
Usual adult dose
Often 300 mg daily in divided doses; adjusted to seizure control and blood levels.
Usual dose in children
Usually 5 mg/kg daily in two or three divided doses; adjusted to response and blood levels.
Common side effects
- Dizziness, drowsiness, and unsteadiness
- Gum overgrowth and excess hair growth
- Rash
- Long-term use may weaken bones
Important warnings
- Do not stop suddenly; seizures may worsen.
- Serious skin reactions and blood disorders can occur.
- Regular blood tests and dental care may be needed.
- Dose changes or switching products require clinical monitoring.
Pregnancy
Can cause birth defects and affect fetal growth; seizure treatment needs specialist review before or during pregnancy.
Breastfeeding
Usually compatible with breastfeeding; monitor the infant for sleepiness, poor feeding, or rash.
Interactions
- Many medicines alter phenytoin levels; levels can become dangerously high or low.
- Phenytoin can reduce effectiveness of hormonal contraceptives.
- Alcohol and sedatives may increase drowsiness and impaired coordination.
- Antacids and tube feeding can reduce absorption.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.