Background: Sphincter of Oddi dysfunction (SOD) refers to an abnormality of SO contractility. It is a benign, non-calculus obstruction to the flow of bile or pancreatic juice through the pancreaticobiliary junction. Although morphine can cause an excitatory effect on SO motility, there are no comprehensive data about opium as a risk factor in inducing SOD in chronic opium abusers. The aim of the study was to assess potential risk factors, especially opium addiction (OA), in patients with SOD.
Material/Methods: In a case-control study, opium addiction, cigarette smoking, cholecystectomy, and periampullary diverticulum in patients with SOD were recorded and compared with healthy subjects. SOD was diagnosed by the Geenen-Hogan classification (type I).
Results: OA (p=0.001) and cholecystectomy (p<0.001) were two independent risk factors in patients with SOD.
Conclusions: Chronic use of opiates by the oral or inhalational route may induce SOD, but whether chronic use of other morphine derivatives or i.v. drug abuse induce this disorder is not clear and needs further evaluation.

Keywords: Case-Control Studies, Cholecystectomy - adverse effects, Iran, Opioid-Related Disorders - complications, Opium, Risk Factors, Sphincter of Oddi Dysfunction - etiology