Cooling-Seeking Behavior and Hot Sensation as Hallmark Toxidromes in Chlorfenapyr Intoxication: A Case Report

Chlorfenapyr is a pyrrole-based insecticide that disrupts mitochondrial oxidative phosphorylation, leading to delayed toxicity marked by hyperthermia and multiorgan failure. While early stages are often described as asymptomatic, recognizing early subtle clinical signs is crucial to improve patient monitoring and management. This report highlights thermogenic symptoms, such as persistent hot sensations and cooling-seeking behaviors, as early warning signs of Chlorfenapyr intoxication, reconsidering existing assumptions of an asymptomatic latent phase.

A 78-year-old woman presented to the emergency department two hours after ingesting several mouthfuls of a pesticide. She was initially stable, with only mild gastrointestinal symptoms. Despite normothermia, she persistently reported feeling hot and demonstrated active cooling-seeking behaviors-kicking off blankets, removing clothing, and using fans-documented in a supplemental video. Laboratory tests showed mild lactic acidosis without early organ dysfunction. On day four, she developed agitation, respiratory distress, hyperthermia (39°C), and generalized muscle rigidity, followed by cardiac arrest unresponsive to resuscitation. Serum obtained at the initial emergency department visit demonstrated a Chlorfenapyr concentration of 0.97µg/mL, measured by gas chromatography-mass spectrometry. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case underscores the importance of recognizing hot sensations and cooling-seeking behaviors as potential early markers of Chlorfenapyr poisoning. Awareness of these subtle but distinctive symptoms can facilitate early confirmatory testing and timely clinical monitoring.