ObjectiveThis study aimed to examine the association between post-Intravenous thrombolysis delirium and 90-day functional outcomes in patients with acute ischemic stroke (AIS).MethodsPatients admitted to the Second Hospital of Jiaxing within 24 hours of symptom onset who underwent intravenous thrombolysis for AIS between January 1, 2023, and December 31, 2024, were retrospectively analyzed. Clinical data were collected to evaluate factors associated with the occurrence of post-reperfusion delirium. Functional outcomes at 90 days were assessed using the modified Rankin Scale, with scores of 0–2 classified as favorable and scores of 3–6 classified as poor. Multivariate logistic regression analyses were performed to identify independent risk factors for the development of post-reperfusion delirium and unfavorable 90-day functional outcomes.ResultsA total of 272 patients were included, comprising 173 males and 99 females, with a mean age of 67.27 ± 11.74 years. Delirium developed in 42 patients, corresponding to an incidence rate of 15.4%. Dysphagia (OR 22.695, 95% CI 9.853 to 52.135, P < 0.001), secondary infection (OR 18.039, 95% CI 8.713 to 37.351, P < 0.001), and hypoproteinemia (OR 9.168, 95% CI 4.514 to 18.618, P < 0.001) were strong independent risk factors for delirium in acute cerebral infarction. Age, illiteracy, increased baseline NIHSS score, the use of sedative drugs, and TOAST classification as large artery atherosclerosis type/cardiogenic embolism type would significantly increase the risk of delirium, and delirium was highly correlated with short-term mortality risk. Delirium was a strong independent risk factor for poor functional prognosis 90 days after cerebral infarction (OR = 12.356, 95% CI 5.892 to 26.008, P < 0.001). At the same time, increasing age, hypertension, multiple comorbidities after admission (electrolyte imbalance, anemia, hypoproteinemia, dysphagia, secondary infection, etc.), increased baseline NIHSS score, and TOAST classification as large artery atherosclerosis type/cardiogenic embolism type would also significantly increase the risk of poor functional prognosis 90 days after cerebral infarction in patients.ConclusionDelirium is significantly associated with poor functional outcomes at 90 days in patients with AIS treated with intravenous thrombolysis, highlighting the clinical importance of early delirium detection. Dysphagia, secondary infections, hypoproteinemia, high baseline NIHSS scores, and large-artery atherosclerotic and cardioembolic stroke subtypes are independently associated with both delirium occurrence and adverse 90-day outcomes.