Hi, Thanks for placing your query here. I can appreciate your concerns. The most common side effects of phenytoin are dose-related. They include: Sedation Nystagmus (eye movement disorder) Decreased coordination Problems with sedation also may be helped by splitting the dose or giving the largest dose at bedtime. About 30% of patients can develop gum hyperplasia. This effect appears to be dose-related and is more common in children. Other appearance-related side effects of long-term use of phenytoin include excessive hair growth & coarseness of facial features . Problems with body movements & coordination may be caused by phenytoin. Rash is a common allergic reaction seen in about 5% . Hope I have answered your query. If you have any further questions I will be happy to help. Best regards.