I had my large colon removed last year and was recently given Fentanyl for pain due to a small intestine obstruction. Within minutes I experienced a hit feeling, began vomiting and confused thinking quickly followed. Emergency doctors administered other drugs to counteract these effects. Is this an allergic reaction? Or a side effect. My overall feeling was one of terror and I would not be keen to take this drug again. I am allergic to morphine and at the moment Pethidine is the only pain relief I can tolerate. The ongoing blockages I'm having are due to adhesions and after 6 bowel operations I do not intend to have any more surgery. Is Pethidine a suitable pain relief in this situation? Cheers Robin