Phenytoin

Seizures and epilepsy

Also known as Dilantin

Phenytoin steadies electrical activity in the brain to prevent seizures, and it's been doing that job for decades. The catch: the gap between too little and too much is narrow, so your doctor uses blood tests to keep your level just right. It also interacts with a long list of other medicines, so tell your doctor and pharmacist about everything you take — including supplements.

How to take it

When

At the same times every day — steady levels are everything with this medicine.

Food

Be consistent — take it the same way each day. Keep antacids a couple of hours away; they can block absorption.

Avoid

Alcohol — it changes your phenytoin level, and heavy drinking is especially risky. Don't drive until you know how it affects you.

Good to know

Brush and floss carefully — phenytoin can make gums grow and swell. Regular dental cleanings help a lot.

Missed a dose?

Take it when you remember, unless it's nearly time for the next dose — then skip it. Missed doses can trigger seizures, so ask your doctor ahead of time what to do if you miss one. Never take a double dose.

Common side effects

Drowsiness
Gum swelling or overgrowth
Mild dizziness or clumsiness
Extra body or facial hair with long-term use

Call a doctor if

A seizure that won't stop — call emergency services
Stumbling, slurred speech, jerky eye movements, or feeling drunk — your level may be too high; call your doctor now
A spreading rash, blistering, or rash with fever or swollen glands — get help now
Thoughts of harming yourself, or new or worsening depression — get help now
Yellow skin or eyes, unusual bruising, or constant infections — call your doctor right away

Educational only. This summary is drawn from public FDA labeling and MedlinePlus and simplified for readability. Your prescription label and your pharmacist always come first — doses and instructions vary from person to person.