Colonoscopy Side Effects and Risks

Colonoscopy side effects are not perhaps something that you would necessarily expect but as with any medical procedure, occasionally these can occur.

It is normal to be a bit anxious when we have a test coming up, especially when the doctor is going to stick a camera right inside us! Really, it is not just you.

Most people are not completely chilled out about having a colonoscopy but a lot of us have to have it done.

Usually the test will pass without incident but stuff can sometimes happen.

It is important before undertaking any test to know the possible risks. Read on to find out about potential complications but also which normal after effects you may experience.

Your doctor should inform you of these things before getting your consent to carry out the test but it always helps to be in the know so that you can ask questions about anything which you are worried about.

Colonoscopy Side Effects - Does Everyone have them?

No. Most people recovery quickly after the procedure and don't feel any ill effects at all.

What are the Normal After Effects That I Might Experience?

Not all colonoscopy side effects are abnormal. Some people experience after effects which are short lived and normal. These can include:

1) Wind or gas resulting from the air which has been pumped into your bowel to inflate it and give the doctor a better view. This will cause your abdomen to be temporarily bloated.The gas will be passed in the normal way, sometimes with a bit of moisture but you may want to keep out of polite company until you have passed all the wind!

2) Short lived, mild abdominal pain (bellyache), especially if you have the gas mentioned above.

Colonoscopy Side Effects - Man With Abdominal Pain

3) A temporary wooziness caused by the sedative which you have been given to relax you during the procedure. In some cases you will have had an anesthetic which might have similar effects. This is why you must not drive on the day of the test or take any important decisions for 48 hours after the colonoscopy.

4) A small amount of blood may appear in your poop if you have had any biopsies or if you have had polyps removed. If the blood is more than a trace or a few spots then this is not normal and you should contact your doctor. If you have had a diagnostic colonoscopy which is only for observation and does not involve any surgery then you should not normally see any blood. Make sure you know what has been done before you go home.

5) Slight soreness around the anus (butt hole). This should not be too bad and will only be temporary as plenty of lubricant should have been used.

6) A few people do suffer from diarrhea after a colonoscopy. This is not really normal but can happen if the gut microbiome is not very strong before the procedure. See below for more details.

Colonoscopy Side Effects - Complications

In a small number of cases colonoscopy side effects are not normal but fall under the category of complications. These are side effects which could put you at risk and may need treatment.

Who is Most Likely to Encounter one of the Colonoscopy Risks ?

Normal colonoscopy side effects are more common if you already have a sensitive bowel. For example if you suffer with irritable bowel syndrome, inflammatory bowel disease or diverticular disease.

Serious complications are more common in certain groups:

  1. People who are elderly and frail
  2. People who suffer from other illnesses such as diabetes, heart disease, bowel cancer, inflammatory bowel diseases
  3. People taking blood thinning drugs
  4. Women have a very slightly increased risk as their bowels are slightly longer and the transverse colon is more bendy
  5. People who are having polyps (small lumps of tissue) removed

How Often Do Colonoscopy Complications Occur?

A study published by the Yale Center for Outcomes Research and Evaluation in 2010 showed that colonoscopy side effects serious enough to require a visit to a hospital occur in otherwise healthy people for an average 1.6% of procedures.

It pointed out that this figure would be larger in high risk patients and where the doctor doing the procedure is inexperienced.

It is a good idea to check that the person doing your colonoscopy has had plenty of practice.

Another study found that people undergoing routine colonoscopy for screening purposes and who did not have any previous symptoms had a very low level of complications.

Out of 21,375 patients; gastrointestinal bleeding occurred in 34 patients, perforations occurred in 4 patients, diverticulitis in 5 patients and post-polypectomy syndrome in 2 patients.

It was found in Canada that 85% of serious complications occurred after removal of polyps.

For more information about colonoscopy complications see this scholarly article.

Serious Colonoscopy Side Effects

  1. Sedative reaction: Some people have a reaction to the sedative used during the procedure. Although this is not common it is more likely in people with previous heart problems
  2. Perforation: When a hole is made in the bowel wall. This is rare but is more common when the procedure is carried out by an inexperienced practitioner.
  3. Hemorrhage: This is most often seen after polypectomy (removal of polyps)
  4. Postpolypectomy electrocoagulation syndrome: Where after the cauterization of a polyp, the wall of the bowel receives a burn which can lead to pain and infection
  5. Gas Explosion: When methane or hydrogen mix with oxygen in the bowel and then are ignited by electrical surgical instruments causing an explosion leading to damage and perforation. Fortunately this is extremely rare
  6. Infection: This will normally clear up with treatment
  7. Death: Colonoscopy specific deaths have been reported at 0.007%

Colonoscopy Side Effects - When Should I Visit the Emergency Room?

During the week after having your colonoscopy if you get any of these colonoscopy side effects you should seek medical attention.

  1. Bleeding: A few spots of blood passed from your bowel is normal especially if you have had a polyp removed or a biopsy (make sure you know before you go home) but any more than this, especially if it is not improving requires a visit to the hospital
  2. Black stool or black diarrhea
  3. Severe abdominal pain that is getting worse or not going away
  4. Abdomen/belly which is hard and tender to the touch
  5. Feeling faint, dizzy or weak
  6. Chest pain or palpitations and irregular heartbeats
  7. Breathing problems
  8. Fever or chills
  9. Vomiting especially if you see any blood or bile
  10. Problems having a  bowel movement or urinating

After Care

When you leave the hospital or clinic after having a colonoscopy you should be given instructions about how to look after yourself and what to look out for but in case you lose them or if unfortunately they forget to give them to you then here are some helpful reminders.

Man Driving Cartoon Car With Red Cross to Indicate No Driving After Colonoscopy
Cartoon Fork Lift Truck With Red Cross To Indicate No Use of Heavy Machinery Post Colonoscopy

It is important that you take it really easy for the first twenty four hours.

  • Do not drive or operate machinery
  • If you have had a sedative have someone stay with you for the first twenty four hours
  • Sorry but no alcohol
  • Take any pain killers, stool softeners and anti-nausea tablets as directed by your doctor
  • Drink plenty of fluids
  • Don't do any heavy lifting or exercise
  • Look out for symptoms that might indicate a complication (see above) and contact your doctor or go to A&E if necessary

Man Carrying Barrel With Red Cross to Indicate No Lifting After Colonoscopy.
Cartoon Man Running With Red Cross Showing How To Avoid Colonoscopy Side Effects
Cartoon Beer with Cross to Show Alcohol Should Not be Consumed Straight After a Colonoscopy

After a day or two you can gradually get back to your normal routines when you feel like it but continue to drink plenty and pay attention to your diet to prevent constipation.

Rebooting Your Microbiome Post Colonoscopy

Prior to your colonoscopy you will have taken strong laxatives and will probably have been on a special diet to make sure that your doctor can get a clear view that is not obscured by poop.

One of the post colonoscopy side effects that some people suffer can be diarrhea because lots of the friendly bacteria in your gut have been cleared out by this procedure.

If your gut microbiome was robust before the procedure with a good diversity of friendly microbes then it will probably bounce back aided by a reboot from your appendix where a 'carbon copy' of your gut microbiome is kept for situations like this.

If however, your gut microbiome was weak; which may be the case in people who suffer from IBS, inflammatory and other bowel conditions, or you do not eat a diverse diet with lots of fruit and vegetables problems may occur. You might also run into problems if you do not have an appendix.

How to guard against this unwanted colonoscopy side effect :

  • For 2-3 days post colonoscopy rest your intestinal tract by eating a low fiber diet and avoiding raw foods, dairy, nuts and seeds.
  • Eat bone broth, vegetable broth, chicken soup, white toast, rice and other bland foods during this rest period (no onions).
  • Take a high quality probiotic. Look for the strains S. Boulardii which is good for diarrhea and L. Plantarum 299v to alleviate bloating.
  • The supplement L-glutamine is good for healing the gut wall.
  • After 2-3 days gradually introduce prebiotic foods as these will feed the newly re-establishing microbiome. (Prebiotic supplements like Inulin and FOS can also be used.)
  • Keep taking the probiotics for several months and establish a varied diet with multi-colored fruits and vegetables including high prebiotic foods like those of the onion family.
  • Prioritize a good night's sleep. Your gut does not like a disturbed night!

N.B. if you suffer from IBS you may need to be careful with prebiotic foods and consider the Low Fodmap Diet which rests the gut for a period of time before re-introducing them.

Should I Have a Colonoscopy?

I can't answer that question for you as you are an individual with your own medical history and your own views. You have to weigh up the risks and benefits with your doctor, however, I can see how you might have been put off after reading about all the colonoscopy side effects in this article!

Do remember the flip side of the coin though. Colonoscopy is a very good way of diagnosing all kinds of gut conditions and preventing cancers by detecting polyps which can progress to cancer. They also save lives by finding early stage cancers that can be treated and cured.

Another thing that some people are concerned about is the time that they will have to take off work to have a screening colonoscopy done. We all have busy lives these days and in tough economic times we may be worried about our jobs and do not want to ask for the time off. Of course though we will have to take much more time off if we become ill because of a missed condition.

So think about possible colonoscopy side effects but don't forget the benefits!


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