Low‐dose (5%) CO2 reliably suppresses absence, febrile, and focal seizures, while higher concentrations (e.g., 10%) may be required in certain genetic contexts, such as Dravet syndrome with Scn1a mutations (see Table 3). This evidence concerns the gene SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.