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Danger of Iron Supplements With a Colonoscopy

author image Eliza Martinez
Eliza Martinez has written for print and online publications. She covers a variety of topics, including parenting, nutrition, mental health, gardening, food and crafts. Martinez holds a master's degree in psychology.
Danger of Iron Supplements With a Colonoscopy
Your doctor is likely to recommend cutting back on iron prior to a colonoscopy. Photo Credit: monkeybusinessimages/iStock/Getty Images

A colonoscopy is a procedure that examines your large intestine and rectum to diagnose several health conditions, including colon cancer and polyps. Despite the outpatient techniques used during a colonoscopy, medication and dietary restrictions begin several days before the examination. Iron supplements are one item to limit before a colonoscopy.

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Preparing for a Colonoscopy

Certain medications and supplements must be avoided for a set amount of time before you have a colonoscopy because they could interfere with the procedure or subsequent recovery. Iron is one such supplement and must be reduced or avoided for several days, helping to keep your colon clean so your doctor can see inside the area. Patients should discuss with their doctors the appropriate amount of time to avoid iron supplements, particularly if taking them for a disease or illness.

Danger of Iron

Iron supplements tend to turn your feces a dark color and a thick consistency, making it difficult for the doctor to detect abnormalities or problems. If this is the case, the procedure may have to be repeated to ensure that a health complication wasn't missed. Your health insurance may not pay for a second exam if you fail to follow your doctor's advice regarding iron supplementation prior to a colonoscopy.

Reducing Iron Intake

Several days before your colonoscopy, stop taking your iron supplements. This gives your body time to flush out any residual iron, clearing your colon for better visualization. You aren't likely to need to reduce your iron intake through food unless you have a health condition that requires a higher than average intake. If you eat a lot of meat and whole grains, ask your doctor about a healthy amount for the days leading up to your procedure.


In some cases, a colonoscopy detects the presence of anemia when other testing isn't conclusive. Anemia is a health condition caused by low iron levels and affects your body's ability to transport oxygen to your internal organs. If your doctor suspects you are anemic and you take iron supplements to counteract the problem, ensure that it is safe to avoid them before the exam. After the procedure, it is likely safe to return to your normal iron supplementation routine.

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