Allergy to Morphine..what happens if i get injured.....?

I had an operation a few years ago and when i was coming around they noticed i was coming out in loads of hives etc after they gave me a shot, but i dont really remember it is so vague. I just remember them running around me. But anyways, so i am allergic to Morphine! What on earth will i be given if i need bad pain relief? I am freaking out incase i get in another situation where i will need major pain relief and i wont be able to get it. :( I have to go in for a colonoscopy soon, and i'm a bit worried about it. Helpp