CDKL5 and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: Fenfluramine (FFA), as designated by International Union of Pharmacology (IUPHAR),1 or (RS)‐ethyl(α‐methyl‐3‐trifluoromethylphenethyl)amine, has shown efficacy in clinical trials as an adjunctive antiseizure medication (ASM) for treatment of patients with Dravet syndrome (DS), Lennox‐Gastaut syndrome (LGS), and CDKL5 deficiency disorder (CDD).