Police in the Halifax area are warning of the dangers of drug use after a woman ended up in hospital because the crack cocaine she took was laced with a drug used to de-worm animals.

Levamisole was used in traditional medicine but now, in some cases, it is turning up in crack cocaine, causing an autoimmune reaction in the skin.

While police say it isn’t prevalent, it does happen and is something drug users should be aware of.

“I’ve seen approximately a half a dozen people with this and virtually all of them have been females and all of them crack cocaine users,” says Dr. Peter Green, a dermatologist with Capital Health.

The woman, who asked not to be identified, is one of them and was also the most severe case seen in Halifax.

She told CTV News she smoked crack cocaine and ended up in the hospital four months ago, during which time she had several skin graphs and a foot amputated.

Green says he saw his first case toward the end of 2009.

“We’re one of the first to actually document it, this with levamisole and the skin changes together,” says Green.

Police say they haven’t seen crack cocaine laced with levamisole often, but they have seen it in drug seizures before.

“Certainly in a couple of cases we have seen it,” says Const. Brian Palmeter. “The test results come back showing this product as being involved or mixed in with the crack cocaine.”

Sgt. Keith MacKinnon of the RCMP’s drug division says levamisole has not been found in any of the samples analyzed by his unit but that doesn’t mean the threat isn’t there.

“We’ve had some limited street information that it is being added,” says MacKinnon. “The addition of levamisole to cocaine is something that the organized crime element likely resorted to because they didn’t have any lidocaine or benzocaine on hand.”

MacKinnon says those local anesthetics are prevalent in cocaine shipments found by the RCMP.

“These are the more popular adulterants to cocaine in order to bulk up the amount of drug that they can sell on the street, and to lower the concentrations so that users won’t overdose on a more pure form,” he says.

While this case involves crack cocaine, MacKinnon says a wide variety of additives are being mixed with all sorts of drugs, making already-risky street drugs even more dangerous.

“The common denominator is that we never cease to be amazed at what the organized crime element is willing to put in these drugs,” he says.

With files from CTV Atlantic's Jacqueline Foster