Inflammation plays a critical role in severe cerebral venous thrombosis (CVT) pathogenesis, but the benefits of anti-inflammatory therapies remain unclear. This study aimed to investigate the association between steroid therapy combined with anticoagulation and the prognosis of acute/subacute severe CVT patients.A prospective cohort study enrolled patients with acute/subacute severe CVT at Xuanwu Hospital (July 2020-January 2024). Patients were allocated into steroid and non-steroid groups based on the treatment they received. Functional outcomes (modified Rankin scale [mRS]) were evaluated at admission, discharge, and 6 months after discharge. Serum high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), cerebrospinal fluid (CSF) IL-6, and intracranial pressure were measured at admission and discharge in the steroid group. Fundoscopic Frisén grades were assessed at admission and 6 months after discharge. Univariate and multivariate logistic regression were used to analyses were used to evaluated associations between steroid use and favorable outcomes (mRS ≤2) at the 6-month follow-up. Paired tests assessed changes in hs-CRP and other variables before and after treatment, and Spearman's correlations were used to analyzed relationships between these changes and functional improvements.A total of 107 and 58 patients in the steroid and non-steroid groups, respectively, were included in the analysis. Compared with the non-steroid group, the steroid group had a higher likelihood of achieving an mRS score of 0-2 (93.5% vs. 82.5%, OR = 2.98, P = 0.037) at the 6-month follow-up. After adjusting for confounding factors, the result remained consistent. Pulsed steroid therapy did not increase mortality during hospitalization or follow-up, nor did it lead to severe steroid-related complications (all P >0.05). Patients in the steroid group showed a significant reduction in serum hs-CRP, IL-6, CSF IL-6, and intracranial pressure at discharge compared to at admission, as well as a significant reduction in the fundoscopic Frisén grade at the 6-month follow-up compare to at admission (all P <0.001). A reduction in serum inflammatory marker levels during hospitalization positively correlated with improvements in functional outcomes (P <0.05).Short-term steroid use may be an effective and safe adjuvant therapy for acute/subacute severe CVT when used alongside standard anticoagulant treatments, which are likely due to suppression of the inflammatory response. However, these findings require further validation in randomized controlled trials.ClinicalTrials.gov, NCT05990894.Copyright © 2025 The Chinese Medical Association, produced by Wolters Kluwer, Inc. under the CC-BY-NC-ND license.