Pointing to a recent study in the Journal of the American Academy of Dermatology, the Los Angeles Sheriff's Department sent out an advisory outlining a problem that has been cropping up in hospitals around the country.
In a June 7 paper, doctors described two cases at Harbor-UCLA Medical Center in Torrance, near Los Angeles, and four cases at the University of Rochester Medical School, in Rochester, N.Y., where patients went to the emergency room complaining of purple blotches on their ears and other areas after taking cocaine.
The patients had suffered a reaction to the veterinary treatment levamisole, the study said, which is banned for human consumption but frequently used to adulterate cocaine.
"We believe this case series may represent the tip of the iceberg as a looming public health problem caused by levamisole," the study stated.
Dr. Noah Craft, one of the study's authors, said he sees a new case at least once every two months and he first started noticing the trend in late 2009. Patients develop blotches that turn from pink to purple and, once the skin has died, to black. Usually these marks are on the ears, mouth and cheeks.
In some cases, patients also develop a potentially fatal condition affecting the bone marrow and leaving them vulnerable to infection. Symptoms usually disappear a few weeks after a patient stops using cocaine and only a small percentage of people are susceptible to having an adverse reaction to levamisole, Craft said.
Sheriff's Capt. Mike Parker said he sent out the advisory to try to encourage people to stop using illegal drugs.
"If not because of the violence in this country and beyond, how about for no other reason so you don't have your extremities turn purple and fall off," he said.
The study states drug dealers may cut cocaine with levamisole because it works in a similar way to the street drug, increasing levels of the neurotransmitter dopamine to the brain's euphoric centers.
Levamisole is the main ingredient used to cut cocaine in the Los Angeles region, Drug Enforcement Administration spokeswoman Sarah Pullen said. Though the agency does not routinely test for contaminants, levamisole has been found in both powder and crystal cocaine.