Complications associated with use of levamisole-contaminated cocaine: an emerging public health challenge.

Levamisole is an immunomodulatory agent that was used to treat various cancers before being withdrawn from the United States market in 2000 because of adverse effects. Levamisole is currently approved as an antihelminthic agent in veterinary medicine, but is also being used illicitly as a cocaine adulterant. Potential complications associated with use of levamisole-laced cocaine include neutropenia, agranulocytosis, arthralgias, retiform purpura, and skin necrosis. Treatment is primarily supportive, and skin lesions typically resolve with cessation of cocaine use. The incidence of hospitalizations related to use of levamisole-contaminated cocaine continues to increase and clinicians should be aware of the more common clinical manifestations.