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Phenytoin
Pronounced FEN-i-toin
Brand names: Dilantin
Type: Antiseizure medicine · All Neurology Medicines
What Phenytoin is used for
- Seizure disorders
- Prolonged seizures in hospital (related form, fosphenytoin)
◆ Kidney note
In kidney failure and low albumin states, standard blood levels mislead — free (unbound) levels are measured instead, a classic kidney-medicine nuance.
Common side effects
- Gum overgrowth
- Drowsiness
- Unsteadiness
- Coarse facial features with long use
- Slurred speech
Important cautions
- The safe range is narrow and blood levels are checked; small dose changes can cause large level changes, especially in older adults
- Long-term use can weaken bones and lower vitamin D and folate
- Interacts with very many medicines, including warfarin and contraceptives
How it comes
Capsules, tablets, liquid, injection (hospital). This guide lists forms only — it never lists strengths or doses.
Toxicity lists: Phenytoin also appears on Medicines That Can Harm the Liver.
Related medicines — Neurology Medicines
Please note: This page is a patient-education summary, not medical advice, and it deliberately contains no doses. Medicines affect everyone differently — always follow your own prescription and talk to your doctor or pharmacist before starting, stopping or changing any medicine.