• Colonoscopy is a rather common examination that is usually performed on an outpatient basis. Complications are rare (less than one in 1,000 examinations). However, complications such as reactions to medication, perforation (tearing) of the intestine, and bleeding may occur, which sometimes requires urgent treatment or surgery.
  • The risks are slightly higher when colonoscopy is used to apply treatment, such as removal of polyps.
  • Inform us immediately if you have any severe pain, black tarry stools or persistent bleeding, or fever/chills in the hours or days after colonoscopy.

Reference : https://www.mountsinai.org/files/MSHealth/Assets/HS/Patient%20Care/Service-Areas/Digestive%20Diseases%20-%20Gastroenterology/MS_Colonoscopy_Preparation_Instructions_MagnesiumCitrate_Sept17.pdf