UMEM Educational Pearls

Category: Toxicology

Title: Leukoencephalopathy from levamisole adulterant in cocaine (and heroin)

Keywords: cocaine, levamisole, leukoencephalopathy (PubMed Search)

Posted: 7/10/2012 by Bryan Hayes, PharmD (Emailed: 7/12/2012) (Updated: 7/12/2012)
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Levamisole is a pharmaceutical with anthelminthic and immunomodulatory properties that was previously used in both animals and humans to treat inflammatory conditions and cancer.

It has been identified as a cocaine adulterant in the U.S. since 2003, with the DEA estimating that by 2009 up to 70% of cocaine seized contained levamisole.

Leukopenia, agranulocytosis, and vasculitis are well known complications of levamisole use.

One important complication to keep in mind is the possibility of multifocal inflammatory leukoencephalopathy (MIL). Although no formal case of leukoencephalopathy in the setting of cocaine use has yet been reported, various neurological side effects were described with levamisole therapy, the most concerning complication being MIL.


Larocque A, Hoffman RS. Levamisole in cocaine: Unexpected news from an old acquaintance. Clin Toxicol. 2012;50:231-41.

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