Acetaminophen Poisoning (N-acetyl-para-aminophenol; APAP) By Gerald F O'Malley, DO, Grand Strand Regional Medical Center; Rika O'Malley, MD, Grand Strand Medical Center Reviewed / Revised Jun 2022 | Modified Sep 2022 View Patient Education Pathophysiology Acute Acetaminophen Poisoning Symptoms and Signs Diagnosis Prognosis Treatment Key Points Chronic Acetaminophen Poisoning Diagnosis Treatment Topic Resources Acetaminophen (Paracetamol)... Rumack-Matthew nomogram for... Stages of Acute Acetaminophen... Acetaminophen poisoning can cause gastroenteritis within hours and hepatotoxicity 1 to 3 days after ingestion.