Objective To assess the clinical efficacy of butylphthalide sequential therapy(BST)as an adjuvant therapy for delayed onset encephalopathy caused by acute carbon monoxide poisoning(DEACMP).Methods DEACMP patients who visited the department of neurology at Yan'an People's Hospital from January 2018 to June 2023 were selected as the research subjects.Using a random number table method,DEACMP patients were randomly divided into hyperbaric oxygen therapy(HBOT)group,glucocorticoid(GC)group(GC combined with,HBOT),and BST group(HBOT,GC combined with BST),all of which were treated continuously for 30 days.The incidence of adverse reactions and clinical efficacy during the treatment among three groups of DEACMP were observed and compared.Inflammation indicators,neurological damage indicators,cognitive function,neurological function,and daily living ability before and after treatment among three groups were compared.Results A total of 120 patients were included in the study,with 40 patients in each group.During the treatment period,no serious adverse reactions were observed in any of the three groups of patients,and no patient terminated treatment due to adverse reactions.The total effective rate of BST group was significantly higher than those of GC group and HBOT group,while the total effective rate of GC group was higher than that of HBOT group(P<0.05).Before treatment,there was no statistically significant difference(P>0.05)in the scores of inflammation indicators,neurological damage indicators,cognitive function,neurological function,and daily living function among the three groups.After treatment,the serum LP-PLA2,SIRI,TNF-α,S100-β,and the NSE levels decreased compared to before treatment(P<0.05),and the indicators of the BST group was lower than those of the HBOT group and GC group,while the indicators of the GC group was lower than those of the HBOT group(P<0.05).After treatment,the MMSE,MoCA,and BI scores of the three groups increased compared to before treatment(P<0.05),but the NIHSS score decreased(P<0.05).In addition,the MMSE,MoCA,and BI scores of the BST group were higher than those of the HBOT and GC groups(P<0.05),while the NIHSS scores were lower than those of the HBOT and GC groups(P<0.05).The MMSE,MoCA,and BI scores in the GC group were higher than those in the HBOT group,while the NIHSS scores were lower than those in the HBOT group(P<0.05).Conclusion Compared with HBOT treatment and HBOT combined with GC treatment,BST adjuvant therapy can improve the clinical efficacy,inflammatory status,cognitive function,and daily living ability of DECAMP patients.