In addition to causing mood swings, swollen glands, skin rash, slurred speech, and hallucinations, Dilantin can affect your blood sugar levels, especially, if you are diabetic. Women who use birth control pills and also take Dilantin may find their contraception less effective. The active ingredients in Dilantin may also migrate into breast milk and harm newborns. Inform your local doctor right awayif any of these rare but serious side effects occur: unusual eye movements, loss of coordination, slurred speech, confusion, muscle twitching, double or blurred vision, tingling of the hands or feet, facial changes (e.g., swollen lips, butterfly-shaped rash around the nose/cheeks), excessive hair growth, increased thirst or urination, unusual tiredness, bone or joint pain or easily broken bones.