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Leukoencephalopathy due to heroin inhalation (chasing the dragon)

Amy T Waldman, MD
Section Editor
Francisco González-Scarano, MD
Deputy Editor
John F Dashe, MD, PhD


Although heroin use by inhalation ("chasing the dragon") first developed in the 1950s [1], the leukoencephalopathy and neurologic symptoms associated with this method of heroin abuse were initially described in 1982 in a report from the Netherlands [2].

"Chasing the dragon" is a method of heroin vapor inhalation that is distinct from smoking or sniffing heroin [1,3]. Other names for this process include "chinesing" and "Chinese blowing." A small amount of heroin powder is placed on aluminum foil, which is heated by placing a match or lighter underneath. The white powder becomes a reddish-brown gelatinous substance that releases a thick, white smoke, which resembles a dragon's tail. The fumes are "chased" or inhaled through a straw or small tube [4].

This topic will discuss the pathogenesis, clinical features, diagnosis, and management of heroin leukoencephalopathy from chasing the dragon.


The mechanism of neurologic injury related to heroin inhalation is unknown. Since heroin leukoencephalopathy has not been observed in users who inject or snort heroin, it is possible that unknown toxins contained in the heroin pyrolysate (the product of chemical change caused by heating) are responsible for the condition [3]. However, the disease was not replicated in rats exposed to this compound [2]. Triethyl tin (TET), a component of inorganic tin, was also suspected since TET poisoning results in vacuolar white matter edema [3,5], but an etiologic role for TET is unlikely, since the TET content in aluminum foil is negligible [3].

Mitochondrial dysfunction may play a role in the development of heroin leukoencephalopathy, as suggested by mitochondrial changes on specimens from brain biopsy [2], by elevated lactate on magnetic resonance spectroscopy [3], and by the clinical improvement with antioxidant therapy that has been reported in a few patients [3]. (See 'Treatment' below.)

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Literature review current through: Nov 2017. | This topic last updated: Jul 28, 2016.
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