If Your Doctor Orders a Colonoscopy, Tell Them These Important Things Before the Procedure
A colonoscopy is one of the most useful tests for examining the inside of the large intestine. It can help doctors investigate symptoms such as rectal bleeding, unexplained changes in bowel habits, abdominal discomfort, iron-deficiency anemia, and unexplained weight loss. It is also widely used to screen for colorectal cancer and detect precancerous polyps before they become dangerous.
Although a colonoscopy is generally considered a safe procedure, what you tell your doctor beforehand matters.
The viral image above says that if your doctor orders a colonoscopy, you should “tell him the following.” That is actually a useful idea—but the important information isn't a secret phrase or a way to avoid the procedure.
Instead, patients should make sure their medical team knows about their medications, medical conditions, allergies, previous procedures, and any problems they've experienced with anesthesia or bowel preparation.
Here are the most important things to discuss.
1. Tell Your Doctor About Every Medication You Take
One of the most important things to disclose is your current medication list.
Don't mention only prescription medications.
Include:
- Prescription drugs
- Over-the-counter medicines
- Vitamins
- Herbal supplements
- Dietary supplements
- Medications taken only occasionally
This is especially important for medications that can affect bleeding or sedation.
For example, patients taking warfarin, apixaban, rivaroxaban, clopidogrel, aspirin, or other blood-thinning medications may need individualized instructions before a colonoscopy, particularly if a biopsy or polyp removal is anticipated.
Never stop a blood thinner on your own.
Stopping certain medications suddenly can create serious risks, including blood clots and stroke.
Your doctor should determine whether a medication needs to be continued, temporarily adjusted, or stopped—and exactly when.
2. Tell Them If You Have Diabetes
If you have diabetes, make sure your healthcare team knows before the procedure.
The preparation for a colonoscopy often involves changing your usual diet, fasting, and drinking a bowel-cleansing solution.
That can affect blood glucose levels.
Diabetes medications, particularly insulin and certain glucose-lowering drugs, may require specific instructions around fasting and the procedure.
Your doctor may provide a modified plan based on:
Your medication, diabetes treatment, blood glucose control, kidney function, and the time of the procedure.
Don't simply skip your diabetes medication without instructions.
3. Mention Kidney, Heart, or Liver Problems
Your doctor should know if you have significant medical conditions, especially conditions involving the kidneys, heart, or liver.
The bowel preparation causes substantial fluid and electrolyte changes in the body.
For most healthy people, the preparation is manageable.
But people with certain medical conditions may require additional precautions or a different preparation strategy.
This is particularly important if you have:
Chronic kidney disease, heart failure, significant liver disease, electrolyte abnormalities, or a history of dehydration.
Your medical team can select the safest preparation for your circumstances.
4. Tell Them About Medication or Anesthesia Reactions
Have you ever had a bad reaction to anesthesia or sedation?
If yes, tell your doctor.
Also mention any previous problems such as:
- Difficulty breathing during anesthesia
- Severe nausea or vomiting
- Allergic reactions
- Unexpected reactions to sedatives
- Difficult airway management
- Being unusually difficult to sedate
A colonoscopy may involve sedation or anesthesia, depending on the facility, patient, and procedure.
Knowing your previous history helps the medical team plan appropriately.
5. Tell Them About Allergies
Don't assume that only medication allergies matter.
Tell your healthcare team about all known medication allergies or serious reactions.
Be as specific as possible.
Instead of simply saying:
“I'm allergic to antibiotics.”
Tell them which antibiotic caused the reaction and what happened.
For example:
“I developed hives and difficulty breathing after taking this medication.”
That information is much more useful to clinicians.
6. Tell Them If You've Had a Previous Colonoscopy
If you've had a colonoscopy before, tell your doctor.
If possible, provide information about:
When it was performed, whether polyps were found, whether biopsies were taken, whether the bowel preparation was adequate, and what follow-up interval was recommended.
Previous pathology reports can be particularly useful.
A history of certain types of polyps can influence when your next colonoscopy should occur.
If you've previously had a difficult colonoscopy or experienced significant discomfort, mention that as well.
7. Tell Them If You Have Had Problems With Bowel Preparation
For many patients, the bowel preparation is the most unpleasant part of a colonoscopy.
If you previously experienced severe nausea, vomiting, dehydration, or difficulty completing the preparation, tell your doctor before starting it again.
Your healthcare team may be able to recommend a different preparation or adjust the instructions.
A colonoscopy depends on the colon being adequately cleaned.
If the bowel isn't sufficiently prepared, the doctor may have difficulty seeing small polyps or other abnormalities, and the procedure may need to be repeated.
Don't simply ignore previous problems with the bowel prep.
Tell the medical team in advance.
8. Tell Them About Your Symptoms
If your colonoscopy was ordered because of symptoms, describe them accurately.
Don't minimize symptoms because you're embarrassed.
Mention:
Rectal bleeding, black stools, persistent diarrhea, constipation, changes in stool shape or frequency, abdominal pain, unexplained weight loss, anemia, or a persistent change in bowel habits.
The timing and pattern can matter.
For example:
When did the symptom begin? Has it become more frequent? Is there blood mixed into the stool or only on the toilet paper? Are you experiencing pain, fever, or weight loss?
These details can help your doctor understand why the colonoscopy is being performed and what they should pay particular attention to.
9. Tell Them About Your Family History
Family history is extremely important in colorectal cancer screening.
Tell your doctor if a parent, sibling, child, or other close relative has had colorectal cancer or certain types of colorectal polyps.
Also provide the approximate age at which the relative was diagnosed, if you know it.
A strong family history can sometimes mean that a person needs screening earlier or more frequently than someone at average risk.
Your doctor may also ask about certain inherited conditions that increase colorectal cancer risk.
10. Tell Them If You're Pregnant or Could Be Pregnant
If you're pregnant, think you might be pregnant, or are trying to become pregnant, tell your healthcare team.
Although colonoscopy can sometimes be performed during pregnancy when medically necessary, elective procedures are generally approached differently.
The medical team will consider the urgency of the procedure, pregnancy stage, sedation, and other factors.
Never hide a possible pregnancy because you're worried the procedure will be canceled.
Your healthcare team needs accurate information to protect both you and the pregnancy.
11. Tell Them If You Have Sleep Apnea or Breathing Problems
This is especially important when sedation is planned.
Tell your doctor if you have:
Sleep apnea, severe snoring, chronic lung disease, asthma, or previous breathing problems during sedation.
Patients with obstructive sleep apnea may require additional monitoring or specific sedation considerations.
If you use a CPAP machine, tell the medical team and follow their instructions regarding whether you should bring it.
12. Ask What You Should Eat and Drink Before the Procedure
Don't guess about the bowel preparation.
Your doctor or endoscopy center should provide specific instructions about:
When to stop solid food, which liquids are allowed, when to stop drinking, and exactly how to take the bowel-cleansing medication.
Instructions can differ depending on the preparation being used and the facility.
Generally, patients are asked to follow a restricted diet before the procedure and consume approved clear liquids during the appropriate period.
Follow the instructions from your endoscopy team rather than a random online checklist.
13. Tell Them If You Have Severe Constipation
People with significant constipation may sometimes require special preparation instructions.
If you frequently have severe constipation or have previously had an inadequate bowel preparation, mention it before the procedure.
Your doctor may recommend additional preparation to improve the chance that the colon will be completely clean.
This can help reduce the possibility of needing another colonoscopy because the doctor couldn't see the colon adequately.
14. Don't Be Afraid to Ask Questions
You have every right to understand why the procedure is being recommended.
Ask:
Why do I need this colonoscopy?
What are you looking for?
Will you remove polyps if you find them?
What type of sedation will I receive?
What medications should I take or avoid?
What should I do if I can't finish the bowel preparation?
When will I receive the results?
These are normal and appropriate questions.
A good medical team should be willing to explain the procedure and its risks.
What You Should NOT Do
One of the biggest mistakes is using information from social media to make your own medical decisions.
Don't stop prescribed medications simply because an online post says they are dangerous before a colonoscopy.
Don't change your bowel preparation instructions without consulting your medical team.
Don't hide medical conditions.
And don't delay a medically necessary colonoscopy because you're afraid of the procedure.
A colonoscopy can identify polyps that can be removed before they develop into cancer, as well as detect colorectal cancer and other abnormalities.
The Bottom Line
If your doctor recommends a colonoscopy, there isn't a secret sentence you need to tell them.
Instead, make sure they have a complete picture of your health.
Tell them about your medications, blood thinners, allergies, diabetes, kidney or heart problems, previous anesthesia reactions, previous colonoscopies, bowel-preparation problems, symptoms, and family history of colorectal cancer or polyps.
Also tell them if you're pregnant or could be pregnant and whether you have sleep apnea or significant breathing problems.
Most importantly, follow the specific preparation instructions provided by your healthcare team.
A colonoscopy may not be anyone's favorite appointment—but proper preparation can make the procedure safer and improve the quality of the examination.
Don't be embarrassed to tell your doctor everything relevant.
The more accurately your medical team understands your health history, medications, and previous experiences, the better they can plan your procedure.
When it comes to a colonoscopy, honest information isn't just helpful—it can be an important part of safe medical care.