"Too Much of a Good Thing": Inadvertent Acetaminophen Overdose in a Low-Weight Elderly Patient.

Commonly used for its analgesic and anti-pyretic properties, acetaminophen ("Tylenol") is effective in managing generalized pain. Complications arise with supratherapeutic dosing of acetaminophen, especially in elderly and frail individuals with diminished glutathione production and reduced metabolic drug clearance potential. Limited cases outline this danger and offer alternative dosing considerations to avoid drug-induced liver injury from acetaminophen (DILI). We present a unique case of an 89-year-old woman without prior liver disease who developed acute liver failure (ALF) while taking recommended dosing of acetaminophen. Physical exam was revealing for generalized abdominal pain, lethargy, and vomiting without ascites, jaundice, or asterixis upon admission. She progressed to ALF with encephalopathy and worsening transaminitis along with evidence of synthetic liver failure. With an elevated acetaminophen level and no prior history of liver disease with Tylenol dosing of 30 mg/kg/dose, DILI due to acetaminophen toxicity was suspected. N-acetylcysteine (NAC) and albumin infusions were initiated with improvement in transaminitis and acute tubular necrosis (ATN). The patient was discharged after 12 days to a rehabilitation facility for strength recovery without long-term sequelae or transplant. While 4000 mg/day dosing regimen is generally safe, it can be dangerous for certain patients. Using the typical pediatric, weight-based regimen of 15 mg/kg as a framework, this patient represents a 66% higher dose than recommended. Considering her frailty and age, this case emphasizes the importance of patient-specific risk factors in acetaminophen dosing and prioritizing an individualized, weight-based approach to analgesic management.