Phenytoin is an anti-epileptic drug, also called an anticonvulsant. Phenytoin works by slowing down impulses in the brain that cause seizures. Phenytoin is used to control seizures. It does not treat all types of seizures, and your doctor will determine if it is the right medicine for you. Phenytoin (FEN-ih-toe-in) is the generic name (non–brand name) of a widely used seizure medicine. Common brand names for this type of medicine include Dilantin, Phenytek, and Epanutin (in the UK), but it is also sold using the name phenytoin or phenytoin sodium. Using generic medicines rather than brand-name ones is often suggested as a way to save money. Sometimes the savings are large, but with other medicines the price differences are pretty small. Investigate and shop around before deciding whether the savings are worth any possible problems. People who switch from brand-name Dilantin to generic phenytoin possibly risk having more seizures or side effects during the changeover, because the body does not absorb the different types in the same way. Switching from one company's generic phenytoin to another company's may have similar risks. So can switching from generic phenytoin to Dilantin. The dosing of phenytoin is patient specific. It may be given once, twice, 3, or 4 times daily. Doses are often adjusted to find the optimal dose based on measurement of blood levels. Taking phenytoin with food may reduce some of the side effects. Elderly patients, debilitated persons, and patients with certain kidney or liver diseases may need lower doses.