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What is the most important information I should know about phenytoin?

If you are taking phenytoin to prevent seizures, keep taking the medication even if you feel fine. You may have an increase in seizures if you stop taking phenytoin. Follow your doctor's instructions.

Do not change your dose of phenytoin without your doctor's advice. Tell your doctor if the medication does not seem to work as well in treating your condition.

Carry an ID card or wear a medical alert bracelet stating that you are taking phenytoin, in case of emergency. Any doctor, dentist, or emergency medical care provider who treats you should know that you are taking a seizure medication.

What is phenytoin?

Phenytoin is an anti-epileptic drug, also called an anticonvulsant. It works by slowing down impulses in the brain that cause seizures.

Phenytoin is used to control seizures. Phenytoin is not made to treat all types of seizures, and your doctor will determine if it is the right medication for you.

Phenytoin may also be used for other purposes not listed in this medication guide.

What should I discuss with my healthcare provider before taking phenytoin?

Do not use this medication if you are allergic to phenytoin.

Before taking this medication, tell your doctor if you are allergic to any drugs, or if you have:

• liver disease;

• porphyria;

• diabetes; or

• a vitamin D deficiency or any other condition that causes thinning of the bones.

If you have any of these conditions, you may need a dose adjustment or special tests to safely take this medication.

Phenytoin can lower your blood sugar. If you are a diabetic, check your blood sugar regularly while you are taking this medication.

FDA pregnancy category D. This medication can cause harm to an unborn baby. Phenytoin may also not be as effective in reducing seizures if taken during pregnancy. Do not use phenytoin without your doctor's consent if you are pregnant. Tell your doctor if you become pregnant during treatment. Use an effective form of birth control while you are using this medication.

Phenytoin can make birth control pills less effective. Use a non-hormonal form of birth control (such as a condom or diaphragm with spermicide) to prevent an unintended pregnancy.

Phenytoin can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

How should I take phenytoin?

Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.

Do not crush, chew, break, or open an extended-release capsule. Swallow the pill whole. It is specially made to release medicine slowly in the body. Breaking or opening the pill would cause too much of the drug to be released at one time. Do not use any phenytoin capsule or tablet that has changed colors. Call your doctor for a new prescription.

The chewable tablet may be chewed, broken, or crushed before swallowing, or it may be swallowed whole.

Shake the oral suspension (liquid) well just before you measure a dose. To be sure you get the correct dose, measure the liquid with a marked measuring spoon or medicine cup, not with a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

To be sure this medication is helping your condition, your blood may need to be tested on a regular basis. You may also need a blood test when switching from one form of phenytoin to another. Do not miss any scheduled appointments.

If you are taking phenytoin to treat seizures, keep taking the medication even if you feel fine. You may have an increase in seizures if you stop taking phenytoin. Follow your doctor's instructions.

Do not change your dose of phenytoin without your doctor's advice. Tell your doctor if the medication does not seem to work as well in treating your condition.

Carry an ID card or wear a medical alert bracelet stating that you are taking phenytoin, in case of emergency. Any doctor, dentist, or emergency medical care provider who treats you should know that you are taking a seizure medication. Store phenytoin at room temperature away from moisture, light, and heat.