Background: Age-specific reporting patterns of potentially life-threatening antiseizure medication (ASM)-associated Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) remain unclear. We examined drug- and age-specific signals in pediatrics and adults. Methods: We analyzed data from the US Food and Drug Administration Adverse Event Reporting System (2013-2025). SJS/TEN and DRESS were identified using Preferred Terms from the Medical Dictionary for Regulatory Activities. We assessed disproportionality in pediatrics and adults, and by age group, using adjusted reporting odds ratios (aRORs) with 95% confidence intervals (CIs) and evaluated report counts and fatal-outcome proportions. Results: Pediatrics accounted for 24.2% of SJS/TEN and 21.3% of DRESS. The five most frequently reported ASMs were lamotrigine, carbamazepine, levetiracetam, phenytoin, and valproic acid, with lamotrigine generally showing the largest aRORs across age groups. In pediatrics aged 0–2 years, phenytoin showed strong signals for SJS/TEN (aROR, 37.09 [95% CI, 20.67-66.57]) and DRESS (aROR, 32.91 [18.15-59.70]). Fatality proportions were highest for valproic acid for both events in pediatrics and for phenytoin in SJS/TEN and levetiracetam in DRESS among adults. Conclusions: These findings highlight the need for age-specific pharmacovigilance strategies to improve the prevention and management of ASM-associated SJS/TEN and DRESS.