Morphine (an opioid) is a strong analgesic. It is used in treatment of all types of pain like Crush injury, Fracture, MI, cancer pain, post-operative pain etc. However in Biliary colic (e.g. due to any stone blocking bile duct), morphine constricts sphincter of Oddi and increase the intrabiliary pressure. This increases the chances of rupture of bile duct. Therefore opioids like morphine are contra-indicated in biliary colic.