Take the missed dose as soon as you remember. If it is almost time for your next dose,
skip the missed dose and take the medicine at your next regularly scheduled time. Do
not take extra medicine to make up the missed dose.
Seek emergency medical attention if you think you have used too much of this
medicine.
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 phenytoin?
Avoid drinking alcohol. It can increase some of the side effects of phenytoin, and
can also increase your risk of seizure.
Avoid taking antacids at the same time you take phenytoin. Antacids can make it harder
for your body to absorb the medication.
Phenytoin can cause side effects that may impair your thinking or reactions. Be
careful if you drive or do anything that requires you to be awake and alert.
Brush and floss your teeth regularly to avoid gum disease that may be caused by taking
phenytoin.
What are the possible side effects of phenytoin?
Get emergency medical help if you have any of these signs of an allergic
reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have any of these serious side effects:
-
swollen glands;
-
fever, sore throat, and headache with a severe blistering,
peeling, and red skin rash;
-
confusion, hallucinations, unusual thoughts or behavior;
-
slurred speech, loss of balance or coordination;
-
restless muscle movements in your eyes, tongue, jaw, or
neck;
-
tremor (uncontrolled shaking);
-
extreme thirst or hunger, urinating more than usual;
-
nausea, stomach pain, low fever, loss of appetite, dark
urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
-
easy bruising or bleeding;
-
swollen or tender gums; or
-
changes in the shape of your face or lips.
Less serious side effects may include:
This is not a complete list of side effects and others may occur. Tell
your doctor about any unusual or bothersome side effect.
What other drugs will affect phenytoin?
Drugs that can increase phenytoin levels in your blood include:
Drugs that can make phenytoin less effective in controlling
seizures include:
Other drugs that can interact with phenytoin include:
-
steroid medicines (prednisone and others);
-
antidepressants such as amitriptyline (Elavil),
clomipramine (Anafranil), imipramine (Janimine, Tofranil), paroxetine (Paxil), and others;
-
antibiotics such as rifampin (Rimactane, Rifadin, Rifamate)
or doxycycline (Doryx, Vibramycin, Adoxa, and others);
-
digitoxin (digitalis, Lanoxin);
-
furosemide (Lasix); and
-
theophylline (Elixophyllin, Theo-Dur, Theo-Bid, Theolair,
Uniphyl).
This list is not complete and there are many other
medicines that can interact with phenytoin. Tell your doctor about all the
prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal
products, and drugs prescribed by other doctors. Do not start using a new medication without
telling your doctor. Keep a list with you of all the medicines you use and show this list to any
doctor or other healthcare provider who treats you.
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