Levamisole, sold under the brand name Ergamisol among others, is a medication used to treat parasitic worm infections, specifically ascariasis and hookworm infections.
Levamisole was discovered in 1966. It is on the World Health Organization’s List of Essential Medicines. It is not commercially available in the United States. Levamisole is also used as a dewormer for livestock.
Levamisole has increasingly been used as a cutting agent in cocaine sold around the globe with the highest incidence being in the United States. In 2008–2009, levamisole was found in 69% of cocaine samples seized by the Drug Enforcement Administration (DEA). By April 2011, the DEA reported the adulterant was found in 82% of seizures.
Levamisole adds bulk and weight to powdered cocaine (whereas other adulterants produce smaller “rocks” of cocaine) and makes the drug appear purer. In a series of investigative articles for The Stranger, Brendan Kiley details other rationales for levamisole’s rise as an adulterant: possible stimulant effects, a similar appearance to cocaine, and an ability to pass street purity tests.
With the increasing use of levamisole as an adulterant, a number of complications have been reported among cocaine users. Levamisole has also been linked to a risk of vasculitis, and two cases of vasculitic skin necrosis have been reported in users of cocaine adulterated with levamisole.
Levamisole-tainted cocaine has caused three deaths and sickened over 100 in US and Canada, as of 2009. It is still widely used as an adulterant in illegal substances in 2022.