Age of Febrile Convulsions
Febrile convulsions occur in children between 6 months and 5 years of age (6-60 months). 1
Typical Age Range
- The standard definition across all major guidelines consistently specifies that febrile seizures occur between 6 months and 5 years of age 1
- This age range is a diagnostic criterion—seizures with fever outside this age range should not be classified as febrile convulsions and warrant investigation for other etiologies 1
Age-Related Clinical Considerations
Risk of Recurrence by Age
- Children younger than 12 months at their first febrile seizure have approximately 50% probability of recurrence 1, 2
- Children older than 12 months at their first event have approximately 30% probability of a second febrile seizure 1, 2
- Of those who experience a second febrile seizure, 50% will have at least one additional recurrence 1
Age-Specific Management Differences
For infants under 12 months:
- Lumbar puncture is almost always indicated to rule out meningitis, given the difficulty in detecting meningeal signs in this age group 1, 2, 3
- The threshold for investigation is much lower due to higher risk of serious bacterial infection 2
For children 12-18 months:
- Lumbar puncture should probably be performed 1
- Clinical judgment regarding meningeal signs becomes more reliable but still warrants caution 1
For children over 18 months:
- Lumbar puncture is indicated only if there are clinical signs of meningism, complex features, excessive drowsiness/irritability, systemic illness, or incomplete recovery within one hour 1
Important Caveats
- The 2-5% prevalence rate applies specifically to this 6-month to 5-year age window 1
- Seizures occurring before 6 months of age require thorough investigation for metabolic disorders, intracranial pathology, or other serious conditions 1
- Seizures with fever occurring after 5 years of age should be evaluated as potential epilepsy or other neurological conditions rather than febrile convulsions 1