It was reported in 1999 that victims of a slimming treatment that used Chinese herbs will receive damages totalling up to 2.5 billion BEF in Belgium's biggest ever case of medical negligence. The pills contained a substance, aristolochic acid, which can damage the kidneys and has produced progressive kidney failure in over 100 of 2,000 women who used the slimming pills the same clinic, which was run by doctors not herbalists. Some patients also developed leaky heart valves. The prescription referred to Stephania tetrandra. As medicinal herbs, Stephania and Aristolochia fangchi are both commonly delivered as roots and the transliteration of the Chinese names is similar: Han Fang Ji and Guang Fang Ji respectively. It is likely that the herb supposed to be Han Fang Ji was misidentified by the exporters in Hong Kong, by the importers in Belgium and by the doctors in the slimming clinic.