Levamisole, used to deworm cattle, pigs and sheep, is found in 80 percent of the U.S. cocaine supply, ABC News reported Thursday. The drug can rot skin off of noses, ears and cheeks.
"It's probably quite a big problem, and we just don't know yet how big a problem it really is," Dr. Noah Craft, a dermatologist with the Los Angeles Biomedical Research Institute, told ABC.
While six patients in the coastal metropolises have presented with the dark purple patches of dying flesh, Craft warned "it's not just in New York and LA. It's in the cocaine supply of the entire U.S."
The flesh rot is caused by an immune system reaction to the drug, which attacks blood vessels in the skin, causing it to starve and suffocate -- but not all users will experience such effects.
Studies in rats indicate the drug may act on the same brain receptors as cocaine, explaining why some drug dealers would cut their cocaine with levamisole to stretch their supplies.
"We don't know who this is going to happen to," Dr. Lindy Fox, a University of California, San Francisco, dermatologist who first discovered the connection, told ABC, adding one patient's entire body was consumed by black, dying flesh.
The skin does heal when the drug is removed from the system, leaving behind a shiny scar.
But when it is active, it has deleterious effects on the immune system, preventing bone marrow from creating white blood cells.
"It's a little bit like having HIV," said Craft. "About 10 percent of those patients will die from severe infections. They may be walking around like a time bomb."