Case Based Pediatrics For Medical Students and Residents
Chapter XVIII.3. Febrile Seizures
Vince K. Yamashiroya, MD
October 2001

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An ambulance brings a 15 month old boy to the emergency department with a seizure associated with fever. He has been in good health except for a high fever that developed today to about 103-104 degrees. His mother gave him a small dose of acetaminophen. About 20 minutes ago when the mother was checking up on her child, she noticed shaking of the arms and legs and his eyes had a blank stare. This went on for what seemed like 5 minutes. She called 911 and an ambulance was dispatched. He has been ill with a high fever today and a slight cough and mild nasal congestion. Just prior to the seizure, he was playing with some toys. There is no vomiting, diarrhea, rash, or fussiness.

Past medical history is unremarkable.

Family history is significant for an uncle who has epilepsy.

Exam: VS T 39.8 degrees C (103.6 degrees F), P 165, RR 30, BP 90/60, O2 sat 100% on RA. He is clingy, alert to his surroundings, and otherwise is in no distress. His mother appears anxious and there appears to be good bonding between her and her child. Skin is without bruising or neurocutaneous stigmata. Anterior fontanelle is closed. Pupils are equal and reactive. EOMs are conjugate. The red reflex is present bilaterally. There is no sunsetting of the eyes. TMs are normal. His mouth exam shows moist mucosa without erythema. The Brudzinski and Kernig signs are difficult to assess. Respirations are regular. Neurologically, he moves both arms and legs equally. His tone appears normal. The rest of the examination is normal.

Febrile seizures are broadly defined as seizures occurring in the presence of fever, but in the absence of central nervous system (CNS) infection, in children ages 6 months to 5 years of age. It is the most common reason for convulsions in children less than 5 years of age, and they occur in 2 to 5% of all children, although it has been reported to be more frequent in Asian countries. In Japan, the rate has been reported to be 7% and in the Mariana Islands 14%. It is thought that the rates in these areas are higher because some of the common infections of childhood may occur earlier in life when children are most susceptible to febrile seizures. Also, since more families sleep in the same room, this may make recognition better than in Western countries (1). The age at which febrile seizures most frequently occur is in the second year of life, and they occur slightly more commonly in boys than in girls. Febrile seizures can be divided into two types: simple and complex. Simple febrile seizures are characterized by the following: duration less than 15 minutes, and generalized. Complex febrile seizures have the following features: duration greater than 15 minutes, multiple within 24 hours, and/or focal (2).

The risk of recurrence after the first febrile seizure is about 33%, and about 9% will have three or more recurrences. The risks for recurrence are: occurrence of the first febrile seizure at a young age; family history of febrile seizures; short duration of fever before the seizure; relatively low fever at the time of the initial seizure; and possibly a family history of an afebrile seizure. It has been observed that the time of recurrence is usually within the first year of onset. Although complex febrile seizures are not usually associated with recurrent febrile seizures, they may be a risk factor for epilepsy later in life. Febrile seizures seem to run in families, but their mode of inheritance is unknown. The risk for other siblings developing febrile seizures is about 10-20%, but may be higher if the parents also have a history of febrile seizures themselves (2).

Febrile seizures usually occur in the first 24 hours of the onset of fever. It has been suggested that it is the rapid rise in the child's temperature, which causes a febrile seizure rather than the actual height of the fever itself; however, there is no substantial proof to support this suggestion. The seizures are usually generalized and tonic-clonic, but other types may be present as well. Parents may describe stiffening, jerking, apnea, cyanosis and incontinence, usually followed by drowsiness (commonly called post-ictal for short). There may be variations to this such as staring without stiffness, jerking movements without prior stiffening, and localized stiffness or jerking. Simple, benign febrile seizures should be short, usually 1 to 2 minutes, but some may be longer (up to 15 minutes). Because of the short duration, medical attention usually occurs after the seizure has ended (2).

Although the diagnosis of febrile seizure is likely in a 6 month to 5 year old with fever and a convulsion, one should consider other causes such as meningitis, encephalitis, Shigella gastroenteritis, medications/toxins (such as diphenhydramine, tricyclic antidepressants, amphetamines, and cocaine), hypoglycemia, electrolyte abnormalities (that could be due to dehydration), shaken baby syndrome, accidental head trauma, and epilepsy (2). Many of these other diseases can be ruled out by a good history, physical examination, and clinical appearance after the seizure has ended.

How should these patients be managed in terms of diagnostic work-up and treatment? Given that febrile seizures are a relatively common phenomenon, should every child with fever and seizures have a lumbar puncture done to rule out meningitis, or CT scan and EEG to look for CNS abnormalities? The American Academy of Pediatrics attempted to answer this in two practice parameters on the evaluation and treatment of children with febrile seizures that were published in 1996 and 1999 (3,4). The recommendations of these two practice parameters are listed below. It should be kept in mind that these are guidelines only and that each case should be individualized according to the particular child, and the situation. One should remember that these guidelines are written for practitioners with a wide range of experience and training; therefore, the points mentioned here are meant to be conservative. Also these guidelines are written for children from 6 months to 5 years of age who had a simple febrile seizure and are neurologically normal. The guidelines do not include children with complex febrile seizures.

1. Lumbar puncture. An LP should be strongly considered in all infants less than 12 months of age because signs and symptoms of meningitis may be minimal or absent in this age group. An LP should be considered in children between 12 months to 18 months of age, since signs of meningitis might be subtle. An LP does not need to be done in children older than 18 months unless they show signs of meningitis (neck stiffness, Brudzinski and Kernig signs) or have symptoms of a CNS infection. Infants and children who were treated with antibiotics prior to the seizure should be strongly considered to have an LP done. This is because antibiotics can mask the signs and symptoms of meningitis (partially treated meningitis). Even if an LP is performed and the results are negative, it is still prudent to be cautious and vigilant since spinal fluid may be normal in the early stages of meningitis (3). The clinical appearance of the child after the seizure has ended plays a very significant role, in that the playful, active child who appears normal, probably does not have meningitis.

2. EEG. An EEG does not need to be performed as part of the work-up for a first time simple febrile seizure. Although the EEG may be abnormal (occipital slowing) in the first month after the seizure, there has been no correlation of this to recurrence risk or the risk for developing epilepsy in the future (3,5). An EEG done 4 to 6 weeks following the seizure should be normal. If it is not, then epilepsy is more likely. In clinical practice this is not usually done after a single simple febrile seizure since an EEG is difficult to do in young children and 4 to 6 weeks have passed, presumably without any more seizures.

3. Laboratory studies. Laboratory tests, such as a CBC, serum electrolytes, calcium, magnesium, phosphorus, and glucose, need not be done routinely. It should instead be tailored to the presenting symptoms. For example, electrolytes and glucose can be checked in a patient who is vomiting.

4. Neuroimaging. CT scan of the head does not need to be done routinely. There is no data available showing that children with febrile seizures have an increased incidence of CNS abnormalities, nor any evidence that febrile seizures lead to structural brain damage.

Recommendations are not as clear-cut for children who develop complex febrile seizures; however, the threshold for performing blood tests, neuroimaging, and EEG is lower. A lumbar puncture should be strongly considered if the patient is young, if there are signs and symptoms of meningitis, if the patient is already on antibiotics, if there is no rapid improvement, or if the patient does not regain full consciousness (5).

If the child develops another seizure, then supportive measures are recommended. During the time the seizure is occurring, the patient should be placed on his/her side to prevent aspiration, and the airway should be maintained. Also nothing should be placed in their mouths. If it is prolonged, then diazepam (Valium) should be given either intravenously or rectally. If the patient has a fever, avoiding overheating by removing blankets and heavy clothes can prevent febrile seizures, in addition to administering antipyretics such as acetaminophen and giving cool baths. Diazepam can also be used to prevent future recurrences of febrile seizures for the next several hours, although its administration as a preventive measure is controversial (5).

Should a patient be hospitalized? Probably not, although it depends what the circumstances are. It is recommended that patients who had a febrile seizure be observed in the emergency department for several hours and reevaluated. After this time, most children would have improved, and if the cause of the fever is known and treated, they can then be sent home. Similarly, in a doctor's office, they can be observed if they are rapidly improving. If they are not improving, then the diagnostic studies mentioned previously should be considered. Circumstances when they should be hospitalized for overnight observation are: the clinical situation is still unstable, there is a possibility of meningitis, and/or the parents are unreliable or unable to cope with the child developing another seizure (1).

An essential component of management is parental counseling. Reassurance should consist of three components. First, parents should be reassured by informing them that although the febrile seizure is frightening, it will not cause brain damage, and the possibility of their child developing epilepsy is small. Secondly, they should also be told that there is a possibility that it could happen again, especially in the first 24 hours. Also one third of children will have at least another febrile seizure later, with most occurring within one year of the episode. Thirdly, if a seizure occurs, the child should be kept on his/her side, and they should observe their child. If the seizure does not stop in 3 minutes, then emergency medical services should be contacted (1).

Long-term pharmacotherapy is probably unnecessary, especially for simple febrile seizures. Although the AAP Practice Parameters discourage use of anticonvulsants in simple febrile seizures, it does mention that giving diazepam during the start of fever in patients with parents having high anxiety is an option. Diazepam is given orally using a dose of 1 mg/kg/day in three divided doses when the child is febrile. Disadvantages of using diazepam are lethargy, drowsiness, ataxia, and masking of a CNS infection. Other medications that have been used to prevent recurrences are phenobarbital and valproic acid. A dose of 5 mg/kg/day of phenobarbital is given once to twice a day. Although they can prevent 90% of recurrences of febrile seizures, they are not without significant side effects. Phenobarbital has been associated with behavioral problems (hyperactivity) and hypersensitivity reactions. Valproic acid has a risk of developing fatal hepatotoxicity, thrombocytopenia, weight changes, gastrointestinal problems, and pancreatitis. These medications have been considered in those patients who have focal paralysis after a seizure, multiple seizures in a young child, and high parental anxiety despite reassurance (1,4). Phenytoin and carbamazepine have no demonstrated efficacy in preventing febrile seizures.

Despite the frightening appearance of the episode, and the parental belief that their child is going to die, simple febrile seizures remain a benign condition with the majority of children having no neurological sequelae. In other words, it does not lead to brain damage or cognitive abnormalities. Although the risk of developing another febrile seizure is moderate, the possibility of epilepsy is very small. For this reason, long-term therapy anticonvulsant therapy is not usually recommended, but practitioners should provide reassurance, education of what to do when their child has another febrile seizure, and antipyretic therapy when a fever is present.

I would like to thank Dr. Yoshio Futatsugi for reviewing this chapter and Dr. Robert Bart for his helpful suggestions and input.


1. At what ages do febrile seizures occur? How common is this problem?

2. In what percentage of patients will febrile seizures occur a second time?

3. What are the differences between simple and complex febrile seizures? Why is it important to know this distinction (think of recurrence risk of febrile seizures, development of epilepsy, and work-up)?

4. A febrile seizure is a diagnosis of exclusion. What other diagnoses should be considered in a child with fever and seizures?

5. According to the guidelines put forth by the American Academy of Pediatrics' Practice Parameter, who should be strongly considered to receive a lumbar puncture?

6. Most patients with febrile seizures can be discharged home. What are three indications for a child who should be hospitalized for overnight observation?

7. Although diazepam (Valium) can be used to prevent recurrences when given at the start of a febrile illness, what are its disadvantages?

8. A key part to management is reassurance. What are three ways parents should be reassured and educated?


1. Aicardi, J. Chapter 15 - Febrile Convulsions. In: Aicardi, J. Epilepsy in Children, second edition. 1994, New York: Raven Press, pp. 253-275.

2. Hirtz, DG: Febrile Seizures. Pediatrics in Review 1997; 18(1): 5-9.

3. Provisional Committee on Quality Improvement, Subcommittee on Febrile Seizures: Practice Parameter: The Neurodiagnostic Evaluation of the Child With a First Simple Febrile Seizure. Pediatrics 1996; 97(5): 769-772.

4. Committee on Quality Improvement, Subcommittee on Febrile Seizures: Practice Parameter: Long-term Treatment of the Child With Simple Febrile Seizures. Pediatrics 1999; 103(6): 1307-1309.

5. Verity CM. Chapter 15 - Febrile Convulsions: A Pragmatic Approach. In: Porter RJ and Chadwick D (eds). The Epilepsies 2, 1997, Boston: Butterworth-Heinemann, pp. 289-311.

Answers to questions

1. 6 months to 5 years. It occurs in 2-5% of all children and is the most common reason for convulsions in children less than 5 years of age.

2. 33%.

3. Simple seizures are characterized by being less than 15 minutes duration and generalized. Complex febrile seizures are greater than 15 minutes duration, multiple within 24 hours, and focal. Simple febrile seizures have a higher risk for febrile seizures. Complex febrile seizures have a higher risk for epilepsy. One should have a lower threshold for performing tests and hospitalization in cases of complex febrile seizures.

4. Meningitis, encephalitis, Shigella gastroenteritis, medications and toxins, hypoglycemia, electrolyte abnormalities, shaken baby syndrome, accidental head trauma, and epilepsy.

5. Infants less than 12 months of age.

6. Unstable clinical situation, possibility for meningitis, and parents unreliable or unable to cope with the child developing another seizure.

7. Disadvantages include lethargy, drowsiness, ataxia, and masking of a CNS infection.

8. 1) Seizure will not cause brain damage and the risk of the child developing epilepsy is small. 2) Possibility that it can happen again, especially in the first 24 hours. One third of children will have at least another febrile seizure with most occurring within one year of the episode. 3) If seizure occurs again, child should be kept on his or her side. If seizure does not stop within 3 minutes, then emergency medical services should be contacted.

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