Seizures are due to a disturbance of the electrical activity of the brain. Epilepsy is a neurological condition in which a person has had at least two seizures not related to other known medical conditions (fever, low blood sugar, etc.), or has had one seizure in conjunction with an EEG suggestive of a seizure disorder.
Febrile seizures are convulsions caused by a fever in infants or small children (usually 6 months to 5 years.) Typically the fever is greater than 102 F and has a rapid onset (often the seizure is the first indication of the fever.) Usually the child loses consciousness and shakes, or becomes rigid with twitching of one area of the body. Most seizures last only a minute or two, but rarely can last longer. During a seizure, make sure that the child is in a safe location, on their side and DO NOT put anything in their mouths. If the seizure lasts more than a minute, or the child is turning blue/not breathing, call 911. Though frightening, simple febrile seizures are harmless, though about 30% of children who have one seizure will go on to have another. The older the age at first seizure, the less likely that the child will again experience one. The vast majority (95-98%) of children with febrile seizures DO NOT go on to develop epilepsy.
For more on febrile seizures, read here (insert)