It was a medical mystery. In the summer of 2008, a man and woman, both in their 20s and both cocaine users, were separately admitted to a Canadian hospital with unremitting fevers, flulike symptoms and dangerously low white blood cell counts. Their symptoms were consistent with a life-threatening immune-system disorder called agranulocytosis, which kills 7% to 10% of patients and is rare except in chemotherapy patients and those taking certain antipsychotic medications.Neither of the Canadian patients fit that bill, but they did have one thing in common: illegal drug use, says Dr. Nancy Zhu, who treated the patients during her hematology fellowship at the University of Alberta Hospital in Edmonton. "We were theorizing that maybe it was something in the cocaine," she says. The medical literature didn't contain any studies linking agranulocytosis with cocaine. However, earlier that same year, in April, a New Mexico lab had identified a small number of unexplained cases of the disorder, also in people who had snorted, injected or smoked cocaine. Later, in 2009, a few cocaine addicts in San Francisco — crack smokers, mostly — began displaying even stranger symptoms, like dead, darkened skin. "It looked like people were getting burns all over their body," says Dr. Jonathan Graf, a rheumatologist at the University of California, San Francisco. "[Their skin was] black, as if you had taken a cigarette butt to it. In some people, it was all over, on their legs and bellies."By this time, back in Canada, a toxicologist at Alberta Hospital had noticed an unusual chemical in the urine of the two cocaine-using patients: levamisole. Zhu contacted him and they put the puzzle together. Further research revealed that levamisole, a drug that was once used to treat colon cancer but is now reserved for veterinary use as a medication to get rid of worms, can cause agranulocytosis in humans. The "burns" seen in Californian patients, who were also suffering from agranulocytosis, were the result of skin infections related to patients' compromised immunity. There have now been several dozen cases of cocaine-related agranulocytosis reported in North America — and one known death. "For some reason, this drug called levamisole keeps popping up," Zhu says. Where is it coming from? According to the U.S. Drug Enforcement Agency, levamisole has become increasingly popular as a "cut" or diluting agent in cocaine and possibly some heroin. It is now found in 70% of all cocaine seized in the United States, up from 30% in 2008. Unlike most cuts — usually inert or relatively harmless substances like the B-vitamin inositol, which are added by lower-level dealers looking to stretch supplies — levamisole appears to be added to cocaine from the outset, in the countries of origin. The substance has been found in various concentrations in cocaine analyzed in various countries around the world, from Switzerland to Australia. And urine tests of cocaine users attending a drug clinic in San Francisco General Hospital in 2009 — one floor above Graf's office — found that 90% of samples were positive for levamisole; similar tests in Seattle revealed that 80% of cocaine users there had levamisole in their systems too."If it's showing up in all those different places, that's a prima facie indicator that it's happening at the highest levels of production," says Craig Reinarman, a sociologist at the University of California, Santa Cruz who has long studied cocaine. But since cocaine is illegal, there's no easy way to remove levamisole from the supply chain. Law enforcement could instead target large purchasers, possibly putting pressure on dealers to switch to other cuts.

Levamisole is cheap, widely available and seems to have the right look, taste and melting point to go unnoticed by cocaine users, which may alone account for the popularity of the cut.

Health officials have stepped up their efforts to call attention to health risks caused by cocaine laced with levamisole, a veterinary anti-parasitic drug. The Substance Abuse and Mental Health Services Administration (SAMHSA) has issued a nationwide health alert to medical professionals, substance abuse treatment centers and other public health authorities.
In humans, levamisole can cause agranulocytosis, a serious, sometimes fatal blood disorder. Ingesting cocaine mixed with levamisole can seriously reduce a person's white blood cells, suppressing immune function and the body's ability to fight off even minor infections, according to SAMHSA. People who use crack or powdered cocaine laced with levamisole can experience overwhelming, rapidly-developing, life-threatening infections, the agency said in a news release.Other serious side effects can also occur. If you use cocaine watch out for:
High fever, chills, or weakness.
Swollen glands,Painful sores (mouth, anal)
Infections that won't go away or gets worse very fast
Skin infections, abscesses
Thrush (white coating of the mouth, tongue, or throat)
Pneumonia (fever, cough, shortness of breath)
"SAMHSA and other public health authorities are working together to inform everyone of this serious potential public health risk and what measures are being taken to address it," said SAMHSA Acting Administrator Eric Broderick.
The number of reported cases of agranulocytosis due to tainted cocaine use is expected to increase as information about levamisole is disseminated through the medical community. Thus far, 20 known cases and two deaths have been confirmed.According to the U.S. Drug Enforcement Administration, Columbia cocaine producers are lacing their product with the medication to give it an extra kick.