Generic Name: phenytoin (oral) (FEN i toyn)
Brand Names: Dilantin, Phenytek
Medically reviewed by P. Thornton, DipPharm. Last updated on Jan 21, 2019.
What is Dilantin?
Dilantin is used to control seizures. Phenytoin does not treat all types of seizures, and your doctor will determine if it is the right medicine for you.
You should not use Dilantin if you also take delavirdine (Rescriptor), or if you are allergic to phenytoin, ethotoin (Peganone), fosphenytoin (Cerebyx), or mephenytoin (Mesantoin). If you are pregnant, DO NOT START TAKING this medicine unless your doctor tells you to. Phenytoin may cause harm to an unborn baby, but having a seizure during pregnancy could harm both the mother and the baby. If you become pregnant while taking Dilantin, DO NOT STOP TAKING the medicine without your doctor's advice. Seizure control is very important during pregnancy and the benefits of preventing seizures may outweigh any risks posed by using phenytoin.
Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, depression, anxiety, or if you feel agitated, hostile, restless, hyperactive (mentally or physically), or have thoughts about suicide or hurting yourself.
Before taking this medicine
You should not use Dilantin if you are allergic to phenytoin, or if you have ever had:
liver problems caused by phenytoin;
if you currently take delavirdine (Rescriptor).
To make sure Dilantin is safe for you, tell your doctor if you have ever had:
suicidal thoughts or actions;
a vitamin D deficiency or any other condition that causes thinning of the bones;
porphyria (a genetic enzyme disorder that causes symptoms affecting the skin or nervous system); or
if you are of Asian ancestry (you may need a special blood test to determine your risk for having a skin reaction to phenytoin).
Some people have thoughts about suicide while taking Dilantin. Your doctor will need to check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.
Seizure control is very important during pregnancy. Do not start or stop taking Dilantin without your doctor's advice if you are pregnant. Phenytoin may harm an unborn baby, but having a seizure during pregnancy could harm both mother and baby. Tell your doctor right away if you become pregnant while taking this medicine.
If you are pregnant, your name may be listed on a pregnancy registry to track the effects of phenytoin on the baby.
If you have taken phenytoin during pregnancy, be sure to tell the doctor who delivers your baby about your Dilantin use. Both you and the baby may need to receive medications to prevent excessive bleeding during delivery and just after birth.
It may not be safe to breast-feed while using this medicine. Ask your doctor about any risk.
How should I take Dilantin?
Take Dilantin exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.
Swallow an extended-release capsule whole and do not crush, chew, break, or open it.
Dilantin Infatabs chewable tablets are not for once-per-day dosing. You must take them 2 or 3 times per day. Follow your doctor's dosing instructions very carefully.
Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).
You may need frequent blood tests. You may also need a blood test when switching from one form of phenytoin to another. Visit your doctor regularly.
Tell your doctor if Dilantin does not seem to work as well in controlling your seizures. Do not stop using Dilantin suddenly, even if you feel fine. Stopping suddenly may cause increased seizures. Follow your doctor's instructions about tapering your dose.
In case of emergency, wear or carry medical identification to let others know you have seizures.
Phenytoin can cause swelling in your gums. Brush and floss your teeth and visit your dentist regularly to help prevent this problem.
Store at room temperature away from moisture, light, and heat.
What happens if I miss a dose?
Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of phenytoin can be fatal. Overdose symptoms may include twitching eye movements, slurred speech, loss of balance, tremor, muscle stiffness or weakness, nausea, vomiting, feeling light-headed, fainting, and slow or shallow breathing.
What should I avoid while taking Dilantin?
Avoid drinking alcohol while you are taking Dilantin. Alcohol use can increase your blood levels of phenytoin and may increase side effects. Daily alcohol use can decrease your blood levels of phenytoin, which can increase your risk of seizures.
Avoid driving or hazardous activity until you know how Dilantin will affect you. Your reactions could be impaired.
Dilantin side effects
Get emergency medical help if you have signs of an allergic reaction to Dilantin (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).
Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.
Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.
Call your doctor at once if you have:
slow or uneven heartbeats, chest pain, fluttering in your chest, and dizziness (like you might pass out);
any skin rash, no matter how mild;
fever, chills, sore throat, swollen glands;
red or swollen gums, mouth sores;
easy bruising, unusual bleeding, purple or red spots under your skin; or
liver problems - loss of appetite, upper stomach pain, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).
Common Dilantin side effects may include:
abnormal eye movement; or
problems with balance or muscle movement.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect Dilantin?
Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.
Many drugs can interact with phenytoin. Not all possible interactions are listed here. TELL YOUR DOCTOR ABOUT ALL OTHER MEDICINES YOU USE, and any you start or stop using during treatment with Dilantin. This includes prescription and over-the-counter medicines, vitamins, and herbal products.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Dilantin only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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Other brands: Phenytek