Phenacetin drug molecule. Computer model of a molecule of the analgesic drug phenacetin. Atoms are represented as spheres and are colour-coded: carbon (green), hydrogen (white), oxygen (red) and nitrogen (blue). Phenacetin is an analgesic (painkiller) and antipyretic (fever reducing drug). Its use is heavily controlled as it is carcinogenic (cancer-causing). It works by having a sedative effect on the sensory tracts of the spinal cord. Phenacetin has been used as a cutting agent by dealers of the illegal drug cocaine because it has similar physical effects to the drug, including local numbing.