Febrile seizures

Nancy McNamara MD (Dr. McNamara of the University of Michigan has no relevant financial relationships to disclose.)
Rachel Gottlieb-Smith MD (

Dr. Gottlieb-Smith of the University of Michigan has no relevant financial relationships to disclose.

Jerome Engel Jr MD PhD, editor. (

Dr. Engel of the David Geffen School of Medicine at the University of California, Los Angeles, received honorariums from Cerebel for advisory committee membership.

Originally released October 18, 1993; last updated January 14, 2020; expires January 14, 2023

This article includes discussion of febrile seizures (also known as febrile convulsions), including simple febrile seizures and complex febrile seizures. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


Febrile seizures are common and have a benign outcome. The genetic basis and pathogenesis of this syndrome are under intense investigation. Evidence-based guidelines suggest minimal investigations are needed for diagnosis, and most children require neither intermittent nor long-term treatment. This clinical article includes summaries from the results of the multicenter study on the consequences of febrile status epilepticus (FEBSTAT).

Key points


• Febrile seizures are the most common seizure type, affecting 3% to 4% of all children.


• Although many affected children have recurrent febrile seizures, the risk of subsequent epilepsy is very small.


• The American Academy of Pediatrics offers guidelines for the evaluation and management of children with febrile seizures.

Historical note and terminology

Febrile seizures (febrile convulsions) are the most common convulsive events in human experience. They were recognized as distinct from other seizures in the mid-19th century, and at that time treatment was redirected to the underlying causes of fever rather than the symptom of a seizure. With the introduction of the thermometer at the end of the 1800s, fever was understood to be the primary factor producing the convulsion. Until the early 20th century, infantile convulsions were thought to be severe and often fatal, and few effective treatments were available. Sentinel studies in the 1940s by Lennox and Livingston investigated risk factors for recurrence and later epilepsy (Livingston et al 1947; Lennox 1949).

In the 1970s two population-based studies formed the foundation of the current view of febrile seizures (van der Berg and Yerushalmy 1969; Nelson and Ellenberg 1978): they are common, many recur, developmental outcome is not altered, and few children later develop epilepsy. In 2008 and 2011, updated evidence-based practice parameters were published by the American Academy of Pediatrics Committee on Quality Improvement, Subcommittee on Febrile Seizures. This, along with the original 1996 publication, and a consensus statement by the International League Against Epilepsy (Capovilla 2009), reflects the current evidence for diagnosis, and treatment recommendations for febrile seizures (American Academy of Pediatrics 2008; American Academy of Pediatrics 2011).

Studies conducted in the United States and Denmark reported that about 3% to 4% of all children will have at least 1 febrile seizure (Nelson and Ellenberg 1976; Vestergaard and Christensen 2009). However, febrile seizures may be more common in other countries. For example a longitudinal study of 54,233 children in Korea reported a prevalence of 11.19% (Choi et al 2019). Although the seizures are associated with fever (greater than 38.5°C by rectal or tympanic membrane measurement), those provoked by central nervous system (CNS) infection are excluded. The peak age for febrile seizures is about 2 years of age with a range between about 6 months and 5 years (American Academy of Pediatrics 1996; Choi et al 2019).

Febrile seizures can be subdivided into “simple” (generalized tonic-clonic semiology, duration less than 15 minutes, and without recurrence within the following 24 hours) or “complex” (focal, duration more than 15 minutes, or occurring in a cluster of 2 or more convulsions within 24 hours). Febrile seizures are generally thought to be benign, and only 2% to 6% of affected children will later develop epilepsy (Nelson and Ellenberg 1976; Dreier et al 2019). The risk of epilepsy following a simple febrile seizure is about 2%, and following a complex febrile seizure, it is still only 5% to 10%. Therefore, febrile seizures can be viewed as a syndrome of acute symptomatic seizures rather than as a true epilepsy syndrome (Engel 2001).

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