The pholcodine story.

Anaphylactic reactions to neuromuscular blocking agents during general anesthesia constitute a major cause of concern and a great source of debate among anesthesiologists. The authors' recent investigations, taking the striking differences of incidence between Norway and Sweden as the point of departure, have provided valuable insights into the pathogenetic mechanisms and the highly uneven geographical distribution of these rare, but dramatic and notoriously unpredictable, events. Eventually, a cough syrup containing pholcodine emerged as the most likely suspect. This new knowledge led to the withdrawal of the drug from the Norwegian market and to the examination of the role of pholcodine-containing drugs in other countries. The present article is a brief summary of the research behind this development.