Phenytoin serum levels can be increased by fluoxetine in some patients and
toxicity may occur. There are also isolated reports of
phenytoin toxicity when
fluvoxamine was also taken.
Phenytoin and sertraline do not normally interact, but 2 patients have shown increased
serum phenytoin levels while taking sertraline. Fosphenytoin, a prodrug of
phenytoin, may interact similarly with these
SSRIs.
Monitor patients for signs of
phenytoin toxicity, such as blurred vision, nystagmus, ataxia or drowsiness. Consider monitoring
phenytoin levels and adjust the dose accordingly. Note that
SSRIs should be avoided in unstable epilepsy and used with care in other epileptics.