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Febrile seizures in children
Last reviewed: 05.07.2025
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Febrile seizures develop in children under 6 years of age with a body temperature above 38 °C, no history of afebrile seizures and other possible causes. The diagnosis is clinical, it is made after excluding other possible causes. Treatment of a seizure lasting less than 15 minutes is supportive. If the seizure lasts 15 minutes or more, treatment includes intravenous lorazepam and, if there is no effect, intravenous fosphenytoin. As a rule, long-term supportive drug treatment of febrile seizures is not indicated.
[ What causes febrile seizures in children?
Febrile seizures occur in approximately 2-5% of children under 6 years of age; in most cases, children are aged 6 to 18 months. Simple febrile seizures last less than 15 minutes and occur without focal symptoms, and if they occur in series, the total duration is less than 30 minutes. Complex febrile seizures last more than 15 minutes, with focal symptoms or postictal paresis, or seizures occur in series with a total duration of more than 30 minutes. Most (more than 90%) febrile seizures are simple.
Febrile seizures occur in the context of bacterial or viral infections. They also sometimes develop after certain vaccinations, such as DPT (pertussis and diphtheria and tetanus toxoid) or MMR (measles, rubella, mumps). Genetic and familial factors may increase susceptibility to febrile seizures. Monozygotic twins have a significantly higher concordance rate than dizygotic twins.
Symptoms of Febrile Seizures in Children
Febrile seizures often occur during the initial rise in temperature, and most occur in the first 24 hours of fever. Generalized seizures are characteristic; most seizures are clonic, but some manifest as periods of atonic or tonic posturing.
Seizures are diagnosed as febrile after other causes have been excluded. Fever may also precipitate seizures in children with a history of afebrile seizures; in such cases, the seizures are not febrile because the child has a predisposition to seizures. If the child is younger than 6 months, has meningeal signs or signs of CNS depression, or develops a seizure after several days of febrile fever, cerebrospinal fluid should be examined to exclude meningitis and encephalitis. Laboratory testing for metabolic disorders or diseases is sometimes necessary. Glucose, sodium, calcium, magnesium, phosphorus levels, and liver and kidney function should be determined if the child has recently had diarrhea, vomiting, or low fluid intake; if there is evidence of dehydration or edema; or if febrile seizures are complex. CT or MRI of the brain should be ordered if focal neurologic symptoms or signs of increased intracranial pressure are present. EEG does not usually identify a specific cause or predict recurrence of seizures and is not recommended after a first febrile seizure in children with normal neurologic examination. EEG should be considered after complex or recurrent febrile seizures.
Treatment of febrile seizures in children
Treatment is supportive if the attack lasts less than 15 minutes. Convulsions lasting more than 15 minutes require the use of drugs to stop them, with careful monitoring of the hemodynamics and respiration. Tracheal intubation may be necessary if the response to drugs is not rapid and convulsions continue.
Drugs are usually given intravenously, using short-acting benzodiazepines (eg, lorazepam 0.05-0.1 mg/kg, which can be repeated after 5 minutes for up to 3 doses). Fosphenytoin 15-20 mg PE (phenytoin equivalent)/kg can be given after 15 minutes if seizures persist. Diazepam rectal gel 0.5 mg/kg can be given once, then repeated after 20 minutes if lorazepam cannot be given intravenously.
Maintenance drug treatment to prevent recurrent febrile seizures or the development of afebrile seizures is usually not indicated unless the child has had multiple or prolonged seizures.
What is the prognosis for febrile seizures in children?
The recurrence rate of febrile seizures in children is about 35%. The likelihood of recurrence is higher if the child is younger than 1 year of age at the first seizure or if the child has first-degree relatives who have had febrile seizures. The likelihood of developing an afebrile seizure syndrome after a febrile seizure is about 2-5%.
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