What are the side effects of Dilantin?

Many adverse effects can occur during phenytoin therapy including:

• dizziness,
• drowsiness,
• difficulty focusing (vision),
• unsteady gate,
• tiredness,
• abnormal involuntary movements,
• nausea,
• vomiting,
• constipation,
• abdominal pain, and
• loss of appetite.

Children and young adults can develop overgrowth of the gums during long-term therapy which requires regular treatment by a dentist. Good oral hygiene and gum massage may reduce the risk. R

ashes can occur in between 1 in 20 and 1 in 10 persons; some may be severe. Additionally, darkening coloration of the skin may develop (more commonly in women). Phenytoin can produce unusual growth of hair in some patients. This reaction most commonly affects the arms and legs but can also affect the trunk and face; it may be irreversible.

Various lymph node reactions have been reported with phenytoin therapy. Lymph nodes may swell, sometimes painfully.

Phenytoin causes serum glucose (sugar) to rise. Thus, blood sugar should be monitored closely when phenytoin is administered to patients with diabetes.

Phenytoin can potentially injure the liver although this is an uncommon occurrence.

Phenytoin can cause the platelet or white blood cell counts to drop, increasing the risk of bleeding or infection, respectively. Phenytoin also can cause anemia.

Because it interferes with vitamin D metabolism, phenytoin can cause weakening of the bones (osteomalacia).

Other important side effects caused by phenytoin include sexual dysfunction, such as:

• decreased libido,
• impotence, and
• priapism (painful, prolonged erections).

Antiepileptic medications have been associated with an increased risk of suicidal thinking and behavior. Anyone considering the use of antiepileptic drugs must balance this risk of suicide with the clinical need for the antiepileptic drug. Patients who begin antiepileptic therapy should be closely observed for clinical worsening, suicidal thoughts or unusual changes in behavior.

What is the dosage for Dilantin?

The dosing of phenytoin is patient specific. It may be given once, twice, 3, or 4 times daily. Doses are often adjusted to find the optimal dose based on measurement of blood levels. Taking phenytoin with food may reduce some of the side effects. Elderly patients, debilitated persons, and patients with certain kidney or liver diseases may need lower doses. The suspension should not be given at the same time as tube feedings since tube feedings bind to phenytoin and reduce its absorption. The recommended adult dose is 100 mg two to four times daily. Some patients may require 200 mg three times daily. Patients stabilized on 100 mg three times daily may receive 300 mg once daily of the extended release capsules.

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.