Testing How Well Magnesium Citrate Capsules Work as Preparation for a Colonoscopy

Inclusion Criteria: * • Scheduled for colonoscopy at Sinai Hospital or Woodholme GI Associates Exclusion Criteria: * • Calculated creatinine clearance under 30ml/min * On PPI and unable to stop for five days before colonoscopy * On H2 blockers and unable to stop for two days before colonoscopy * achlorhydria * Previous colon surgery * Cardiovascular disease, including uncontrolled congestive heart failure, unstable angina pectoris, or recent (3 months) percutaneous transluminal coronary angioplasty, myocardial infarction, or coronary artery bypass graft surgery * Colon disease, including chronic constipation (\<2 bowel movements per week for \>1 year), ileus and/or acute obstruction, ileostomy, right or transverse colostomy, subtotal colectomy (≥50% of colon removed) with ileosigmoidostomy, hypomotility syndrome, megacolon, or idiopathic pseudo-obstruction * Pregnant women