Eptoin (phenytoin sodium) when taken in overdose can cause nystagmus, ataxia and dysarthria, tremors, lethargy, slurred speech, blurred vision, nausea, and vomiting. Such adverse effects may occur if the drug taken is more than 30 mg per kg of the body weight. The normal dose in children is 5 mg per kg of the body weight. If the weight is 12 kg or more, side effects are unlikely to be serious.