Clinical, Pharmacological and Molecular Effects of IV and Oral Acetaminophen in Adults With aSAH

Inclusion Criteria: * Diagnosis of subarachnoid hemorrhage (must be confirmed by CT, CT angiography, lumbar puncture, or MRI). * Fisher Grade between 1-3 (subarachnoid blood without signs of intraventricular hemorrhage or parenchymal extension). * Placement of an external ventricular drain. * Adults aged 18-100 years. Exclusion Criteria: * Anyone under the age of 18 or over the age of 100. * Adult patients with subarachnoid hemorrhage with interventricular hemorrhage or parenchymal extension (Fisher Grade 4). * Contraindication to acetaminophen such as a known hypersensitivity, severe hepatic impairment, or severe active liver disease. * Severe renal impairment (creatinine clearance ≤ 30 mL/min).