Inclusion Criteria- Diagnosis of subarachnoid hemorrhage (must be confirmed by CT, CTA, 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).