About This Page
This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Febrile seizures occur between 6 months and 5 years in children without CNS infection or prior afebrile seizures
- Simple febrile seizure: generalized, <15 minutes, and occurs once in 24 hours
- Complex febrile seizure: focal, >=15 minutes, or recurrent within 24 hours
- Well-appearing child with simple febrile seizure usually needs source-of-fever evaluation and reassurance, not EEG, CT, MRI, or chronic antiseizure medication
- Lumbar puncture is based on meningitis concern, age, immunization status, and clinical appearance — not automatically required for every simple febrile seizure
Overview
Febrile seizures are the most common seizure disorder of childhood. They are provoked by fever rather than direct CNS infection and are usually benign. The diagnostic priority is excluding meningitis, encephalitis, toxic ingestion, metabolic derangement, or epilepsy when features are atypical. Step 2 CK frequently tests the distinction between simple and complex febrile seizures and the appropriate restraint in testing.
Epidemiology
Febrile seizures affect about 2-5% of children in the United States, typically between 6 months and 5 years. Recurrence is common, especially with young age at first seizure, family history, low fever at seizure onset, and short fever duration before seizure. Simple febrile seizures only slightly increase later epilepsy risk; complex features and abnormal baseline neurodevelopment increase risk more.
Clinical Features
Symptoms
Generalized tonic-clonic seizure during febrile illness
Brief postictal sleepiness followed by return to baseline
Focal movements, prolonged seizure, or repeated seizures in 24 hours
Neck stiffness, persistent altered mental status, photophobia, or toxic appearance
Age younger than 6 months or older than 5 years
History of prior afebrile seizures or developmental abnormality
Signs
Fever with otherwise reassuring examination and normal neurologic status after recovery
Meningismus, bulging fontanelle, petechiae/purpura, or persistent irritability
Focal neurologic deficit or Todd paralysis after a focal seizure
Dehydration, otitis media, viral exanthem, pneumonia, or UTI source may be present
Failure to return to baseline mental status after expected postictal period
Investigations
First-line
Clinical classificationDetermine age, seizure duration, generalized vs focal features, recurrence within 24 hours, and return to baseline
Fever source evaluationHistory and examination guide testing for viral illness, otitis media, pneumonia, UTI, meningitis, or other infection
GlucoseCheck immediately if ongoing seizure, altered mental status, poor intake, or ill appearance
Second-line
Lumbar punctureIndicated if meningitis signs or concerning history/exam; consider in incompletely immunized infants or those pretreated with antibiotics
Urinalysis/urine cultureCommon occult source in young children when no clear source of fever is identified
Electrolytes/toxicologyIf vomiting/diarrhea, dehydration, persistent altered mental status, ingestion concern, or atypical age/features
Specialist
NeurologyComplex febrile seizure with persistent deficits, recurrent prolonged seizures, abnormal development, or concern for epilepsy
Emergency/PICUFebrile status epilepticus or airway compromise requires acute seizure management and higher-level care
1
Acute seizure management
- ABCs, protect from injury, place child in lateral position, check glucose if seizure ongoing or mental status abnormal
- Benzodiazepine if seizure lasts >5 minutes: lorazepam IV, midazolam intranasal/buccal/IM, or diazepam rectal if no IV access
- Treat febrile status epilepticus according to pediatric status epilepticus protocols
2
Simple febrile seizure
- Evaluate the cause of fever based on age, immunization status, and clinical findings
- No routine EEG, neuroimaging, CBC, electrolytes, or lumbar puncture in a well-appearing, fully immunized child without meningitis signs
- Provide caregiver education about recurrence, seizure first aid, and when to seek emergency care
3
Complex or atypical features
- Focal, prolonged, recurrent, persistent altered mental status, or abnormal neurologic examination warrants broader evaluation
- Consider CNS infection, electrolyte disturbance, trauma, toxic ingestion, epilepsy, or structural lesion depending on presentation
- Neurology follow-up is reasonable when complex features or baseline neurologic abnormalities are present
4
Prevention
- Antipyretics improve comfort but do not reliably prevent febrile seizure recurrence
- Chronic antiseizure medication is not recommended for simple febrile seizures because harms outweigh benefits
- Rescue benzodiazepine may be prescribed for children with prior prolonged seizures
Complications
- Recurrence: About one-third have another febrile seizure, especially if first seizure occurs before 18 months
- Febrile status epilepticus: Prolonged seizure requiring emergency benzodiazepine and escalation
- Parental anxiety: Education is important because events are frightening despite generally benign prognosis
- Epilepsy risk: Low after simple febrile seizure; higher with complex features, family history, and neurodevelopmental abnormality
- Missed meningitis: Persistent altered mental status or meningismus should not be attributed to a benign febrile seizure
USMLE Step 2 CK Exam Tips
- 1Simple febrile seizure = generalized, <15 minutes, single in 24 hours
- 2Well-appearing child with simple febrile seizure does NOT need EEG, CT, MRI, or chronic antiseizure therapy
- 3Lumbar puncture is for meningitis concern, not because every febrile seizure needs CSF
- 4Antipyretics do not prevent recurrence; they are for comfort
- 5Age range is 6 months to 5 years — outside this range should trigger broader thinking
- 6Febrile seizure plus persistent altered mental status, neck stiffness, or petechiae = evaluate for meningitis/sepsis
- 7Seizure lasting >5 minutes = benzodiazepine
practicetest your knowledge on febrile seizuresApply what you've learnt with USMLE Step 2 CK-style questions from the iatroX Q-Bank — pediatrics and beyond.
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