It usually takes around 4 weeks for phenytoin to work properly. This is because the dose of phenytoin needs to be increased slowly to prevent side effects. You may still have seizures or pain during this time.

How effective is Dilantin?

Status epilepticus and other acute seizures are often treated with a solution of phenytoin given intravenously. Within 20 minutes, 60% to 80% of patients will respond. A related medication, fosphenytoin (Cerebyx), is also effective for this purpose and can also be given by an intramuscular injection.

How does Dilantin make you feel?

Headache, nausea, vomiting, constipation, dizziness, feeling of spinning, drowsiness, trouble sleeping, or nervousness may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.