"Bite a hot pepper, and after the burn your tongue goes numb. The Baltimore Sun reports that Capsaicin, the chemical that gives chili peppers their fire, is being dripped directly into open wounds during highly painful operations, bathing surgically exposed nerves in a high enough dose to numb them for weeks. As a result patients suffer less pain and require fewer narcotic painkillers as they heal. 'We wanted to exploit this numbness,' says Dr. Eske Aasvang, a pain specialist who is testing the substance. Capsaicin works by binding to C fibers called TRPV1, the nerve endings responsible for long-lasting aching and throbbing pain. Experiments are under way involving several hundred patients undergoing various surgeries, including knee and hip replacements using an ultra-purified version of Capsaicin to avoid infection. Volunteers are under anesthesia so they don't feel the initial burn."
http://www.baltimoresun.com/news/health/bal-te.peppers30oct30,0,1228065.story
http://science.slashdot.org/article.pl?sid=07/10/30/196215