Phenytoin is a prescription medication which is available both as a generic drug and under the brand name Dilantin. Despite the availability of a generic formulation, some doctors and pharmacists prefer the brand name due to subtle differences. No one is exactly sure how this anticonvulsant works, but it is believed to calm excitable, overactive neurons in the brain that can lead to a seizure. Phenytoin is used to treat partial seizures and tonic-clonic seizures in people who have epilepsy. Dilantin is available in 30 and 100 milligram capsules and in 50 milligram chewable tablets. An orange-vanilla flavored liquid suspension is also available. Phenytoin is extremely patient specific and should be taken exactly as prescribed. Take the tablet form with water and use a medicine spoon to measure the liquid suspension. The most commonly reported side effects of phenytoin include decreased coordination and memory problems, but please ask your doctor for a complete list. Also, tell your doctor IMMEDIATELY if you experience a rash, swollen lymph nodes, or any other significant changes. Phenytoin can reduce the effectiveness of birth control pills and should be used cautiously in people with liver disease. Ask your doctor for a full list of medications and conditions that should not be combined with phenytoin. Dilantin is the oldest and most frequently prescribed medication for seizures in the United States. However, this medication must always be used under the direct care of a physician. Please ask for and review all of the patient information provided by your doctor before taking phenytoin.