Lithium toxicity has been seen in patients concurrently treated with 
phenytoin. Note that 
symptoms of 
toxicity have developed even with 
lithium levels within the normal range. 
 The interaction is not well established. Patients taking 
lithium should be aware of the 
symptoms of 
lithium toxicity and told to immediately report them should they occur. This should be reinforced when they are given 
phenytoin.