Do i have to stop smoking before an endoscopy/colonoscopy?

You should quit.: You don't have to quit in order to have the procedure. But truthfully you should try to quit smoking as it is very unhealthy and is the number one preventable cause of death in the developed world. Especially someone like you, who is having endoscopy, that means you are at even greater risk of developing esophageal cancer. If you are interested, ask your doc about medical ways to help you quit.