Overview
Febrile Seizure
Quick Reference
Critical Alerts
- Most are simple and benign: Reassurance is key
- Rule out meningitis in atypical presentations: LP if indicated
- Complex febrile seizures need more workup: >15 min, focal, recurrent within 24h
- Benzos for prolonged seizure >5 min: Treat as per status epilepticus
- No routine EEG or imaging for simple FS: Not indicated
- Parent education is essential: Reduce anxiety, teach seizure management
Key Diagnostics
| Criteria | Simple FS | Complex FS |
|---|---|---|
| Duration | <15 minutes | >5 minutes |
| Type | Generalized | Focal features |
| Recurrence | None within 24h | Multiple within 24h |
| Post-ictal | Brief, complete recovery | Prolonged or focal deficit |
Emergency Treatments
| Situation | Treatment | Dose |
|---|---|---|
| Active seizure > min | Benzodiazepine | Lorazepam 0.1 mg/kg IV or Midazolam 0.2 mg/kg IM/IN |
| Fever control | Antipyretics | Acetaminophen 15 mg/kg or Ibuprofen 10 mg/kg |
| Post-ictal | Observation | Monitor for recovery |
| Meningitis concern | LP, Empiric antibiotics | If indicated |
Definition
Overview
A febrile seizure is a seizure associated with fever (≥38°C/100.4°F) occurring in children 6 months to 5 years of age, in the absence of central nervous system infection, metabolic derangement, or history of afebrile seizures. They are the most common type of seizure in childhood and are typically benign with an excellent prognosis.
Classification
Simple Febrile Seizure (70-80%):
| Criterion | Definition |
|---|---|
| Duration | <15 minutes |
| Type | Generalized (no focal features) |
| Recurrence | Does not recur within 24 hours |
| Recovery | Complete, no post-ictal focal deficit |
| Age | 6 months to 5 years |
| No CNS infection | Negative lumbar puncture or low clinical suspicion |
Complex Febrile Seizure (20-30%): Any of the following:
- Duration >15 minutes
- Focal features (one side of body, eye deviation)
- Recurrence within 24 hours
- Post-ictal focal deficit (Todd's paralysis)
Febrile Status Epilepticus:
- Febrile seizure lasting >30 minutes
- Or multiple seizures without return to baseline
Epidemiology
- Incidence: 2-5% of children (6 months to 5 years)
- Peak age: 12-18 months
- Recurrence rate: 30-35% (higher if first seizure <18 months)
- Gender: Slightly more common in males
- Genetics: Strong family history component
Etiology
Associated Conditions (Fever source):
| Category | Common Causes |
|---|---|
| Viral infections | Roseola (HHV-6), influenza, URI, gastroenteritis |
| Bacterial infections | AOM, UTI, pneumonia |
| Post-vaccination | Especially MMR, DTP (rare, benign) |
Risk Factors for Febrile Seizures:
- First-degree relative with febrile seizures
- Daycare attendance (more infections)
- Developmental delay
- Neonatal unit stay >30 days
Pathophysiology
Mechanism
The exact mechanism is not fully understood, but likely involves:
- Temperature sensitivity: Immature brain has lower seizure threshold with fever
- Cytokine effects: Pro-inflammatory cytokines (IL-1β) lower seizure threshold
- Ion channel effects: Temperature affects neuronal excitability
- Genetic predisposition: Multiple susceptibility loci identified
Why Children 6 Months to 5 Years?
- Maturing but vulnerable nervous system
- Before 6 months: Maternal antibodies, lower infection rates
- After 5 years: Brain more resistant to seizure with fever
Relationship to Epilepsy
- Simple FS: Minimal increased risk of epilepsy (1-2% vs 1% general)
- Complex FS: Slightly higher risk (~4-6%)
- Most children with FS do NOT develop epilepsy
Clinical Presentation
Seizure Description
Simple Febrile Seizure:
Complex Febrile Seizure:
History
Key Questions:
Physical Examination
General:
Infectious Source Evaluation:
| System | Findings |
|---|---|
| ENT | AOM (bulging TM), pharyngitis |
| Respiratory | Crackles, wheezing (LRTI) |
| Abdominal | Diarrhea, vomiting history |
| Skin | Rash (roseola, viral exanthem) |
| GU | Suprapubic tenderness (UTI) |
Neurological:
Generalized tonic-clonic activity
Common presentation.
Duration typically 1-3 minutes
Common presentation.
Brief post-ictal phase (minutes)
Common presentation.
Full recovery to baseline
Common presentation.
Red Flags
Concerning for Meningitis or Serious Cause
| Finding | Concern | Action |
|---|---|---|
| Prolonged altered consciousness | Meningitis, encephalitis, status | LP, cultures, empiric antibiotics |
| Meningeal signs | Meningitis | LP, empiric antibiotics |
| Bulging fontanelle | Increased ICP, meningitis | LP (if safe), imaging |
| Petechial/purpuric rash | Meningococcemia | Emergent antibiotics |
| Focal seizure or focal deficit | Complex FS, structural lesion | Consider imaging, EEG |
| Multiple seizures in 24h | Complex FS | More workup |
| Age <6 months or > years | Outside typical FS age | More workup |
| Immunocompromised | Higher infection risk | Lower threshold for LP |
| Partially treated with antibiotics | Masking meningitis | Consider LP |
Complex FS Features (Need More Evaluation)
- Duration >15 minutes
- Focal features
- Recurrence within 24 hours
- Prolonged post-ictal >30 minutes
- Post-ictal focal deficit
Differential Diagnosis
Other Causes of Seizure with Fever
| Diagnosis | Key Features |
|---|---|
| CNS infection (meningitis/encephalitis) | Altered mental status, meningeal signs, CSF abnormal |
| Epilepsy (triggered by fever) | Prior afebrile seizures, known epilepsy |
| Electrolyte abnormality | Hyponatremia, hypoglycemia |
| Complex febrile seizure | Prolonged, focal, recurrent |
| Febrile status epilepticus | >0 minutes, requires aggressive treatment |
| Shivering/rigors | Not a seizure; responsive, no post-ictal |
| Breath-holding spell | Triggered by crying/upset, younger age |
Diagnostic Approach
Simple Febrile Seizure
Routine Testing NOT Indicated:
- No EEG
- No neuroimaging (CT or MRI)
- No routine LP
- No routine labs
Identify Fever Source:
- Focus clinical exam on source
- Consider UA/culture if no source (UTI common in young children)
Indications for Lumbar Puncture
AAP Guidelines:
| Age | LP Recommendation |
|---|---|
| <6 months | Consider LP (low threshold) |
| 6-12 months | LP if unimmunized for Hib/pneumococcus or if antibiotics given |
| >2 months | LP only if meningeal signs or clinical concern |
| Any age with complex FS | Consider LP |
| Pretreated with antibiotics | Consider LP (may mask meningitis) |
| Prolonged altered consciousness | LP indicated |
Indications for Neuroimaging
- Focal seizure
- Focal neurological deficit
- Signs of increased ICP
- Not a typical simple FS
- Suspicion of abuse or trauma
Indications for EEG
- NOT indicated for simple FS
- Consider for:
- Recurrent complex FS
- Concern for epilepsy
- Abnormal neurological exam
Laboratory Studies
- Not routinely required
- Consider BMP if concerned about electrolyte abnormality
- UA/culture if no fever source identified
Treatment
Principles of Management
- Manage active seizure: If ongoing >5 minutes
- Identify fever source: Treat underlying infection
- Supportive care: Fever control, observation
- Reassurance: Most are benign
- Parent education: Essential
Active Seizure Management (If Ongoing)
Duration <5 minutes:
- Position safely (recovery position)
- Protect from injury
- Monitor airway
- Time the seizure
- Most will stop spontaneously
Duration >5 minutes (Treat as status epilepticus):
| Step | Medication | Dose |
|---|---|---|
| 1st line | Lorazepam IV | 0.1 mg/kg (max 4 mg) |
| Alternative | Midazolam IM/IN | 0.2 mg/kg (max 10 mg) |
| Alternative | Diazepam rectal | 0.5 mg/kg (max 20 mg) |
| 2nd line (if ongoing) | Repeat benzo OR levetiracetam/fosphenytoin | Per status protocol |
Fever Control
Antipyretics:
| Agent | Dose |
|---|---|
| Acetaminophen | 15 mg/kg PO/PR q4h |
| Ibuprofen | 10 mg/kg PO q6h (> months) |
Note: Antipyretics do NOT prevent febrile seizure recurrence, but treat fever and improve comfort.
Treat Underlying Infection
- Antibiotics if bacterial source (AOM, UTI, pneumonia)
- Supportive care for viral illness
Observation
- Simple FS: Brief observation until return to baseline
- Complex FS: Longer observation, may need admission
Prophylactic Anticonvulsants
NOT Recommended for Simple FS:
- AAP does not recommend continuous or intermittent anticonvulsant prophylaxis
- Risks outweigh benefits
When Considered (Rare, discuss with neurology):
- Recurrent prolonged FS
- Febrile status epilepticus
- Significant parental anxiety with high recurrence risk
Disposition
Discharge Criteria (Simple Febrile Seizure)
- Brief, self-limited generalized seizure
- Returned to baseline alertness
- Fever source identified or low-risk evaluation
- No meningeal signs
- Well-appearing child
- Reliable caregivers with education
- Follow-up arranged
Admission Criteria
- Complex febrile seizure requiring ongoing observation
- Febrile status epilepticus
- Concern for meningitis/encephalitis
- Unable to identify fever source in young infant
- Prolonged post-ictal state
- First seizure in child <6 months or >5 years
- Social concerns, unable to return
Neurology Referral
- Recurrent complex febrile seizures
- Febrile status epilepticus
- Abnormal neurological exam
- Concern for epilepsy
Follow-Up
| Situation | Follow-Up |
|---|---|
| Simple FS, discharged | PCP in 24-48 hours |
| Recurrent FS | Pediatric neurology |
Patient Education
Condition Explanation (For Parents)
- "A febrile seizure is a convulsion caused by a rapid rise in body temperature, usually from a viral infection."
- "These are common—about 2-5% of children have one."
- "Simple febrile seizures are benign and do NOT cause brain damage."
- "Most children outgrow them by age 5."
- "There is a slightly higher chance of epilepsy, but most children do NOT develop epilepsy."
What to Do If Another Seizure Happens
- Stay calm
- Place child on side (recovery position)
- Protect from injury (move objects away)
- Do NOT put anything in mouth
- Time the seizure
- Call 911 if >5 minutes or abnormal breathing/color in between
Prevention
- Antipyretics do NOT prevent febrile seizures
- Keep child comfortable during febrile illness
- Treat infection appropriately
When to Return
- Seizure lasting >5 minutes
- More than one seizure within 24 hours
- Not waking up or acting normal after seizure
- Stiff neck, severe headache
- Rash that doesn't blanch
- Difficulty breathing
- Concern for dehydration
Special Populations
Age <6 Months
- Febrile seizures rare at this age
- Higher concern for serious bacterial infection
- Lower threshold for sepsis workup and LP
- Consider alternative diagnoses
Recurrent Febrile Seizures
- 30-35% recurrence rate after first FS
- Higher risk if:
- Age <18 months at first FS
- Lower temperature at first FS
- Family history of FS
- Shorter duration of fever before seizure
- Still benign prognosis overall
Febrile Status Epilepticus
- Seizure >30 minutes OR multiple seizures without return to baseline
- Higher risk of hippocampal injury (rare)
- Higher recurrence of prolonged seizures
- Consider rescue benzodiazepine prescription for home
- Neurology referral
Vaccinations
- Some vaccines (DTP, MMR) associated with FS
- Risk is very low (~1 in 3,000 for MMR)
- Does NOT contraindicate future vaccination
- Reassure parents
Quality Metrics
Performance Indicators
| Metric | Target | Rationale |
|---|---|---|
| Avoid routine labs for simple FS | >0% | Guideline adherence |
| Avoid routine EEG for simple FS | >5% | Not indicated |
| Avoid routine imaging for simple FS | >5% | Not indicated |
| LP for meningeal signs | 100% | Rule out meningitis |
| Parent education documented | 100% | Reduce anxiety, improve safety |
Documentation Requirements
- Seizure description (duration, type, focal features)
- Time to return to baseline
- Fever source evaluation
- Neurological exam
- Meningeal signs assessment
- Disposition rationale
- Parent education
Key Clinical Pearls
Diagnostic Pearls
- Simple FS = benign: Reassurance is treatment
- Complex features require more evaluation: Duration >15 min, focal, recurrent
- LP if any doubt about meningitis: Especially <12 months or pretreated
- No routine EEG or imaging for simple FS: Saves cost and anxiety
- Identify fever source: Treat underlying infection
- Return to baseline is key: Prolonged confusion is concerning
Treatment Pearls
- Most seizures stop spontaneously: Within 2-3 minutes
- Benzos for >5 minutes: Don't wait
- Antipyretics do NOT prevent FS: But improve comfort
- Prophylactic anticonvulsants NOT recommended: Risks > benefits
- Rectal diazepam for home: Consider for recurrent prolonged FS
- Reassurance is therapeutic: Parental anxiety is high
Disposition Pearls
- Simple FS can go home: With education
- Complex FS may need admission: For observation
- Neurology for recurrent complex FS: Or status
- Good prognosis overall: Most outgrow by age 5
References
- Subcommittee on Febrile Seizures. Febrile Seizures: Guideline for the Neurodiagnostic Evaluation of the Child With a Simple Febrile Seizure. Pediatrics. 2011;127(2):389-394.
- Steering Committee on Quality Improvement and Management. Febrile Seizures: Clinical Practice Guideline for the Long-term Management of the Child With Simple Febrile Seizures. Pediatrics. 2008;121(6):1281-1286.
- Patel N, et al. Febrile Seizures. BMJ. 2015;351:h4240.
- Kimia A, et al. Utility of lumbar puncture for first simple febrile seizure among children 6 to 18 months of age. Pediatrics. 2009;123(1):6-12.
- Shinnar S, et al. Febrile seizures and mesial temporal sclerosis: No association in a long-term follow-up study. Neurology. 2012;79(12):1215-1224.
- Offringa M, et al. Prophylactic drug management for febrile seizures in children. Cochrane Database Syst Rev. 2017;2:CD003031.
- Leung AK, et al. Febrile seizures: an overview. Drugs Context. 2018;7:212536.
- UpToDate. Clinical features and evaluation of febrile seizures. 2024.