What medications should be avoided before a colonoscopy?

Medications to Avoid Before a Colonoscopy

Patients should discontinue blood thinners, iron supplements, and certain diabetes medications before colonoscopy, while most other medications can be continued with clear liquids up until 2 hours before the procedure. 1

Blood Thinners and Anticoagulants

Blood thinners require special management before colonoscopy due to the risk of bleeding during polypectomy:

• Warfarin (Coumadin): Should be stopped 5-7 days before colonoscopy if polypectomy is anticipated. An INR ≤1.5 is generally considered safe for the procedure 1, 2, 3

• Prasugrel and other thienopyridines: Should be stopped at least 7 days before colonoscopy if possible 4, 5

• Clopidogrel (Plavix): Should be discontinued 7 days before colonoscopy, especially if polypectomy is anticipated 3

• Direct oral anticoagulants (DOACs): Should be temporarily discontinued due to their rapid onset and offset of action; periprocedural bridging is generally not necessary 5

• Aspirin and NSAIDs: Can generally be continued for routine colonoscopy, as studies show no significant increase in post-polypectomy bleeding risk 6, 7

Important: The decision to stop anticoagulants must balance the risk of thromboembolism against the risk of bleeding. For high-risk patients (e.g., recent cardiac stent placement), consult with the prescribing physician before stopping these medications 5.

Other Medications to Avoid

• Iron supplements: Should be stopped 7 days before colonoscopy as they can darken stool and interfere with visualization

• Magnesium-based preparations: Should be avoided in patients with chronic kidney disease due to potential magnesium toxicity 1

• GLP-1 receptor agonists: Should be stopped 1-7 days before colonoscopy (depending on the specific agent) as they delay gastric emptying 1

Medications That Can Be Continued

Most other medications can be taken with a small sip of water up until 2 hours before the procedure, including:

• Blood pressure medications
• Heart medications
• Seizure medications
• Psychiatric medications
• Thyroid medications

Special Considerations

Diabetes Medications

• Oral diabetes medications: Should be held the morning of the procedure
• Insulin: Dose should be reduced according to physician instructions

Simethicone

• Can be taken: Simethicone can actually be beneficial as an adjunct to bowel preparation, with doses of 320-1,200 mg shown to improve visualization by reducing bubbles 1, 8

Timing Considerations

• Split-dose preparation: The second dose should begin 4-6 hours before colonoscopy and be completed at least 2 hours before the procedure 1

• Same-day preparation: For afternoon colonoscopies, preparation can begin 4-6 hours before the procedure and be completed at least 2 hours before 1

Common Pitfalls to Avoid

1. Stopping aspirin unnecessarily: Evidence shows aspirin can typically be continued safely 6

2. Inadequate timing of anticoagulant discontinuation: Follow the specific timeframes for each medication type 3

3. Failing to consult with prescribing physicians: For patients on anticoagulants for high-risk conditions, consultation with the prescribing physician is essential 5, 9

4. Stopping medications that should be continued: Most chronic medications should be continued with a small sip of water

5. Not following clear liquid restrictions: All medications taken should be with minimal clear liquid (small sip of water) within 2 hours of the procedure 1