S5630 Beyond the Label: Unrecognized Chronic Acetaminophen Toxicity From Over-the-Counter Misuse

Introduction: Acute acetaminophen (APAP) toxicity is a cause of acute liver injury; however, chronic use is underrecognized, particularly in older adults who may unintentionally misuse over-the-counter (OTC) medications due to polypharmacy, mislabeling, or misunderstanding of ingredients. This case highlights the diagnostic challenges of chronic APAP toxicity and underscores the importance of thorough medication reconciliation in all clinical settings. Case Description/Methods: The patient is a 73-year-old man with a history of type 2 diabetes mellitus and chronic low back pain who presented as a direct admit for concerns of APAP toxicity. On the day prior, he visited his primary care provider (PCP) in clinic for follow-up of his low back pain. There, it was discovered he had been self-medicating his back pain with APAP 7.5 grams daily for 4 weeks, believing it was aspirin. The patient reported no symptoms other than feeling more aloof for the last few weeks. He was sent to the emergency department, where his liver enzymes were markedly elevated. Imaging revealed hepatomegaly with suspected steatosis and possible cirrhosis. However, his APAP level was undetectable, so the patient was sent home without N-acetyl cysteine (NAC) therapy. Given the significantly elevated liver enzymes and concerns for APAP toxicity, the PCP arranged for direct admission the next day for gastroenterology evaluation and NAC. On presentation, the patient had new-onset right upper quadrant abdominal pain and jaundice without nausea, vomiting, or diarrhea. Liver enzymes improved after one cycle of NAC. His course was complicated by incidentally found multifocal hepatocellular carcinoma, for which hepatology and oncology follow-ups were arranged. Discussion: This case illustrates the risks of unrecognized chronic supratherapeutic OTC medication use, particularly in elderly patients with chronic pain. The absence of elevated serum APAP levels typical of acute toxicity prompted providers to overlook the diagnosis. Additionally, the delayed presentation and nonspecific symptoms of mild confusion and abdominal discomfort reflect the subtle onset of chronic toxicity. The patient’s misunderstanding of the medication highlights the need for clinicians to review all medications, including OTCs, and even ask patients to bring them to visits for verification. Early identification and NAC treatment despite normal APAP levels are essential, but vigilance remains key in prevention.