This study aimed to evaluate the safety of reducing or withdrawing anti-seizure medications (ASMs) in a cohort comprising both adults and children with drug-resistant epilepsy (DRE) undergoing ketogenic diet therapy (KDT). We conducted a comprehensive analysis of clinical profiles in adults and children with DRE who had adhered to KDT for at least 6 months. Successful withdrawal or reduction of an ASM was defined as discontinuation or dose reduction without subsequent resumption or increase and without initiation of any new ASM throughout the entire follow-up period. Changes in the ASM load were calculated specifically for adult patients. The study enrolled 56 participants (34 children and 22 adults) with DRE, with 64.3% achieving successful withdrawal of at least one ASM. The probability of ASM withdrawal remained consistent for children (64.7%) versus adults (63.6%), as well as for responders (62.5%) versus non-responders (68.8%), and it was not associated with other clinical factors. Early ASM reduction (including withdrawal) after diet initiation occurred in 15 patients (26.8%), with treatment outcomes comparable to those of the remaining participants. Among the 22 adults, the mean values of ASM load reduced by 24.5%, with a similar magnitude observed for responders (24.2%) versus non-responders (25.1%). In addition, adults tend to have a slower elevation in serum ketone levels compared to children. This study demonstrates the safe achievability of ASM withdrawal through KDT in most patients with DRE, irrespective of age or seizure frequency reduction.