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Side effects of screening colonoscopies

According to 'The Annals Of Internal Medicine,' the rate of serious complications from colonoscopy screening is “10 times higher than for any other commonly used cancer-screening test.” This number doesn't include deferred complications, such as internal bleeding, severe anemia, heart attack, stroke, pulmonary embolism, pneumonia, kidney failure, intestinal obstruction, and others.

These complications explain why, according to the Telemark Polyp Study I, colonoscopy screening increases relative mortality by 57%. Thus, if you are seriously considering to undergo screening, your odds of being killed or injured by the side effects of colonoscopy may actually exceed your odds of getting colorectal cancer in the first place [1].

Adding insult to injury, all that prep, fear, risk, expense, embarrassment, and stress are for naught anyway — screening colonoscopy offers near zero protection from colon cancer, as I explain in my Death By Colonoscopy report.

Miralax Safety Alert

What gives? Well, a conventional colonoscopy isn't simply a routine doctor's visit, but an ambulatory surgical procedure performed under general anesthesia. According to the same Annals of Internal Medicine, serious complications occur in 0.5% of all cases [link].

Unreported medical errors and deferred side effects, such as severe anemia caused by blood loss, pulmonary embolism, heart attack, or stroke related to blood clots caused by general anesthesia, pneumonia, persistent post-operative infection, or kidney failure and acute diverticulitis caused by colon prep, may easily add up to another percent or two.

If, for argument sake, the combined number of complications, side effects, and medical errors tally up to just 1%, it means that 140,000 people are injured annually by 14 million estimated screenings alone. This rate of “collateral damage” is just as high as the incidence of colorectal cancer itself, and, perhaps, is just as deadly, especially for seniors — a primary target group for “preventative” colonoscopies.

Even if you take at face value the claim that screening colonoscopies have reduced colorectal cancer mortality by 5% or about 2,500 lives annually, it means 56 people  have been needlessly harmed to save just one life (140,000 / 2,500).

Then, consider the 1 in 5 chance of getting any other cancer following a single virtual colonoscopy. Radiation exposure from just one abdominal CT scan (at 5 to 10 mSv) is two to three thousands times more potent than a single dental x-ray, and 2 to 3 times higher than the  estimated exposure to a “dirty” nuclear bomb estimated at just 3 mSv [link].

Cancer From Radiation Risk Estimates

As scary as the “dirty bombs” are, an explosion in the center of Fairfax County, VA, a populous suburb of Washington, DC, would affect only 19,500 people [link]. That is 50 to 100 times less people than are  being nuked annually in the radiology centers across the nation while administering unneeded and cancer-causing abdominal CT scans.

Since preventive colonoscopies became an outright fad after Ms. Couric‘s televised colonoscopy in March of 2000 [2], close to 30,000 more people annually have been affected by colon cancer.

Without a doubt, unnecessary screening colonoscopies — conventional and virtual alike, and almost all related to the Katie Couric Effect, — contribute to these new cancers by causing the following common side effects:

Common side effects of colonoscopy

The side effects of colonoscopy are similar to problems associated with any surgical procedure and are caused by the confluence of like factors: bowel prep, mechanical and surgical traumas by instruments, anesthesia, hypothermia, stress, opportunistic infections, fluctuations of blood sugar, excessive fluid consumption, sudden diet modification, and so on. Each stage introduces its own set of complications:

A few days following colonoscopy, side effects are commonly exacerbated by following routine advice to increase fiber intake. These complications may differ in nature depending on the degree of dysbacteriosis.

Patients with severe dysbacteriosis may not experience much if any bacterial fermentation of fiber and associated gases and bloating but may be affected by large stools, straining, constipation, hemorrhoids and obstruction. Those who retained some bacteria following the test may experience fermentation-related bloating, cramps and flatulence.

Post-traumatic stress syndrome (PTSS) is commonly associated with any invasive procedure in general and cancer screening in particular. It is especially bothersome among persons in a high-risk group or susceptible to anxieties and depression. PTSS commonly interferes with digestion because an elevated level of stress hormones and muscular tensions inhibit the secretion of digestive fluids and peristalsis.

Here is a specific list of the most likely side effects you may experience after the colonoscopy in (more or less) chronological order:

dotSevere dehydration

Osmotic laxatives used for bowel prep cause a significant loss of body fluids. A rehydration isn‘t simply a matter of drinking more water — it takes time because the body can only absorb a limited amount of water at any given time. Resuming solid food soon after a colonoscopy may intensify dehydration because solid food, particularly protein, requires several liters of saliva and digestive juices. 

YOUR ACTION: Hydrate yourself properly before the procedure. The best form of hydration is freshly-squeezed cucumber juice (with skin on) — a sugar-free source of potassium, about 600 mg per cup; mineral water with a high-mineral content; and several salty snacks because sodium chloride is essential to retain water. Start rehydration several days in advance — it isn't a matter of just drinking several glasses of water before the procedure.

dotIntoxication and food poisoning

These two related conditions may result from a rapid resumption of solid food particularly containing protein. The preceding liquid diet and residual effect of anesthesia cause the reduction of gastric digestion (i.e. an inadequate level of hydrochloric acid and proteolytic enzymes). Inadequate acidity may fail to properly sterilize incoming food from bacterial and viral pathogens.

The unchecked presence of pathogens may cause a condition commonly referred to as “stomach flu”: — nausea, vomiting, diarrhea, abdominal cramps and other symptoms typical to infectious disorders of the GI tract. The enzymatic deficiency (combined with low acidity) results in putrefaction (rotting) of undigested proteins inside the stomach and intestines. This process produces cadaverine — a foul-smelling substance produced by protein hydrolysis. A gradual absorption of this substance into the blood may cause symptoms similar to food poisoning.

YOUR ACTION: Resume solid food gradually. Refrain from proteins for at least 3 days after the colonoscopy. Chew well and thoroughly to improve digestion. Do not drink fluids after meals, only 30 to 60 minutes before, so fluids have a chance to get down into the small intestine where they assimilate. Do not mix proteins with carbohydrates and fiber to ease the digestive load. Do not overeat. Do not consume more than one protein-containing meal a day. Use proteolytic enzyme supplements to assist in the digestion of protein. Make sure to consume the recommended 4-6 grams of salt daily to facilitate the proper synthesis of hydrochloric acid (salt is a source of chloride (Cl). Do not take acid reducers because they inhibit the digestion of protein and release of proteolytic enzymes. Do not take dietary fiber because it extends digestion and causes obstructions. Use the Colorectal Support Kit instead to normalize defecation without fiber.

dotEsophageal, gastric, duodenal, and intestinal obstructions

Foods are propelled through the digestive tract via peristalsis — a coordinated action of smooth muscles that make up the circumference of the esophagus, stomach, and intestines. Anesthetics, even mild ones, switch off peristalsis for a good chunk of the time particularly in combination with common drugs for hypertension, heart disease, anxiety, depression, convulsions, pain relief (opiates), and some others.

If you follow your doctor‘s advice, and take fiber-rich food or fiber laxatives soon after the colonoscopy, there is a good chance of clogging up the GI tract with this rapidly expanding fiber. The obstruction may cause a broad number of digestive complications and problems and may require emergency surgery. Nausea and vomiting, particularly with bile, is one of the most prominent symptoms of intestinal obstruction.

YOUR ACTION: Avoid fiber supplements and food rich in fiber. Use Colorectal Recovery Kit instead to normalize defecation without fiber.

dotColorectal bleeding

This is a serious concern for people taking blood thinners and/or aspirin. The removal of polyps leaves a wound. It may not properly heal for several reasons: vitamin K deficiency related to prior dysbacteriosis and low-fat diets, ongoing therapy with blood thinners and/or aspirin, collagen synthesis defects related to a low level of vitamin C and protein deficiency, an infection from pathogenic bacteria, elevated acidity and/or a high-level of alcohols from fermenting fiber, mechanical impaction from expanded fiber, irritation and inflammation caused by laxatives and, finally, colon stretching from gases and/or straining.

YOUR ACTION: Use Colorectal Recovery Kit before and after colonoscopy to facilitate healing, reduce inflammation, restore intestinal flora and enable normal and timely defecation.


An outcome of dysbacteriosis and inflammatory conditions inside the colon, both caused by bowel prep and dietary fiber, particularly soluble fiber found in psyllium laxatives (Metamucil). The lack of intestinal bacteria compromises stool formation. Inflammation blocks fluids from absorption and causes an additional oozing of mucus into the lumen (colon cavity). Both conditions result in diarrhea (liquid stools). Excessive use of soluble fiber in food and laxatives blocks the absorption of digestive fluids and further exacerbates diarrhea.

YOUR ACTION: Use Colorectal Recovery Kit immediately following a colonoscopy to restore intestinal flora and eliminate inflammatory bowel disease. Avoid fiber laxatives and food that is rich in fiber. Exclude bananas, prunes and prune and beet juice. These common remedies for constipation contain sorbitol — a sugar alcohol and potent laxative. Sorbitol is a primary substance behind diabetic nerve and blood vessel damage, the factors behind diabetic neuropathies (nerve damage), retinopathy (blindness), erectile dysfunction, kidney failure, heart disease and amputation of lower limbs. (87,000 a year in the United States alone).

dotSmall, hard stools

This condition is common after colonoscopy, particularly among patients who refuse to take fiber and results from dysbacteriosis caused by bowel prep. Live and dead intestinal bacteria retain fluid (moisture) in formed feces. Even a 10% to 15% reduction of fluids (75% to 80% is a norm) in stools causes small, hard, lumpy stools.

This is, incidentally, why insoluble fiber is recommended in the first place: cellulose (an indigestible component of fiber) expands with water and bulks up stools. Alas, cellulose isn‘t as efficient at holding water as bacteria because it dries out faster and results in anal abrasions. It gets fermented by the remaining bacteria which results in gases and bloating and requires a good dosing of insoluble fiber to keep the moisture locked inside - this results in diarrhea and more fermentation. On top of this, enlarged (bulked up) stools require straining which causes hemorrhoids, abrasions, fissures, prolapses and nerve damage.

YOUR ACTION: Use Colorectal Recovery Kit instead of fiber immediately following colonoscopy to restore normal stool morphology.

dotFlatulence, bloating, abdominal cramps.

Intestinal bacteria reside in the mucous membrane and inside the appendix. Many bacteria will die after the bowel prep but some may survive, particularly inside the appendix. When, following a doctor‘s advice, fiber is added to the diet, these bacteria spring into action and ferment the fiber — a process no different from beer, dough, or wine making. Gases, produced by fermentation, cause flatulence, bloating and cramps.

Women are particularly sensitive to gas-related bloating because the genitourinary organs reside in the same tightly packed abdominal cavity. The uterus and fallopian tubes are particularly sensitive to pressure before and during periods, hence the typical after-effects of premenstrual syndrome (PMS). The alcohols and acidity related to fermentation may cause mucosal inflammation which further inhibits the absorption of gases, and increases bloating, flatulence and pain.

YOUR ACTION: Do not use fiber and fiber laxatives following colonoscopy. Your doctor‘s advice to use fiber is wrong because it is based on outdated and falsified information. Use Colorectal Recovery Kit instead to restore proper stool morphology without fiber and laxatives.


Internal and external hemorrhoids are caused by large stools (from fiber) and the ensuing straining to expel them, or by intense, often involuntary contractions of anal and pelvic muscles in response to diarrhea, caused by dysbacteriosis and soluble fiber.

YOUR ACTION: Use Colorectal Recovery Kit instead of fiber immediately following colonoscopy to restore normal stool morphology (i.e. reduce stool size, maintain moisture, eliminate straining.)

dotAnal fissures

Same reasons as above. The mechanical pressure of large stools on the narrow, anal canal passage-way causes skin tears. Daily effort to move the bowels and straining doesn‘t allow the wounds to heal and the tear becomes larger and larger. Medication, infection (by passing stools) and malnutrition further interfere with healing.

YOUR ACTION: Use Colorectal Recovery Kit to facilitate the healing process and maintain soft, semi-liquid stools until complete healing. Thereafter, to maintain proper stool morphology so you don‘t have to strain.

dotChronic constipation

All of the above reasons. As fiber makes stools larger and larger, the anal- canal gets smaller and smaller from internal hemorrhoids. The ensuing pain and discomfort from large stools passing through the narrow anal-canal lead to incomplete emptying and stools remaining in the large intestine get larger, denser, and drier. A vicious cycle of dependence on laxatives to move the bowels ensues.

YOUR ACTION: Use Colorectal Recovery Kit to restore and maintain proper stool morphology.

dotIrritable bowel syndrome

An alternating pattern of constipation and diarrhea along with abdominal pain, cramps, and discomfort caused by bloating and flatulence. It doesn‘t take a genius to recognize the cause — they are all enumerated above. If you already have a history of irritable bowel syndrome, a colonoscopy and more fiber will only make this situation worse.

YOUR ACTION: Use Colorectal Recovery Kit and follow my recommendation in Fiber Menace. I‘ve been IBS-free since I started doing   the same and so are thousands of my readers. This is the safest and least expensive approach to become and stay IBS-free for the rest of your life.

You aren‘t likely to hear about it from the mainstream medical sector any time soon because it will deprive countless endoscopists, gastroenterologists, hospitals, clinical labs, radiology centers, and drug companies from one of their top money makers, according to the National Institutes of Health:

“As many as 20 percent of the adult population, or one in five Americans, have symptoms of IBS, making it one of the most common disorders diagnosed by doctors. It occurs more often in women than in men and it begins before the age of 35 in about 50 percent of people.” [7]

dotColon obstruction

Excessive accumulation of unfermented fiber inside the colon on one hand and an incomplete emptying of stools on the other, may eventually cause fecal impaction and colon obstruction. It‘s usually manifested by paradoxical diarrhea — a condition when fluids incoming from the small intestine flow around impacted stool and create a diarrhea-like condition. If you aren‘t overweight (fat interferes with manual examination), an obstruction is easily determined during physical examination. Otherwise, an x-ray with contrast solution may be required. Insist on an abdominal x-ray instead of a CT-scan to reduce your radiation exposure.

YOUR ACTION: DO NOT use Colorectal Recovery Kit or any other medication/laxatives, particularly fiber, to manage this condition. This is a real medical emergency which requires an immediate visit to an emergency room for examination and if necessary, manual disimpaction (a procedure performed by a surgeon or a specially-trained nurse). After proper diagnosis and disimpaction, use Colorectal Recovery Kit to prevent any repeat occurrence.

dotDiverticulitis (the aggravation of diverticulosis)

Up to a quarter of people before 50 may already have one or more diverticula. This number grows to 50% after age 60. These diverticula result from large stools and straining caused by all of the factors listed above and namely, large stools and straining related to the excess use of dietary fiber.

Since most colonoscopies start after 50, the recommendation to hit on fiber immediately thereafter is particularly damaging to people already affected by diverticulosis. When large stools and fiber get trapped inside diverticula, they are likely to cause an inflammation of unprotected mucosa which may result in bleeding and severe pain related to ulceration, necrosis, or perforation.

YOUR ACTION: Do not use fiber and fiber laxatives following colonoscopy. The advice to use fiber is wrong and it is based on outdated and falsified information. Use Colorectal Recovery Kit instead to restore proper stool morphology without fiber.

dotUlcerative colitis

The predisposition to ulcerative colitis — an inflammation and ulceration of the colon mucosa following colonoscopy is quite high because all the preconditions are there: mucosal inflammation, lack of protective bacteria, inadequate coagulation, poor healing, diarrhea, and excess use of fiber.

YOUR ACTION: It is easier to prevent than treat ulcerative colitis. Use Colorectal Recovery Kit to prevent its occurrence or relapse, particularly if you have a history of diarrhea and/or ulcerative colitis.

dotCrohn‘s disease

Crohn‘s disease is a condition similar to ulcerative colitis except its localization may happen anywhere along the gastrointestinal tract and it has a strong auto-immune component. The reasons behind it and preventive actions are similar to ulcerative colitis.

dotFormation of pre-cancerous polyps and cancers

I believe the genetic and ethnic aspects of colon cancer are highly exaggerated. Polyps and cancers — abnormal cellular growths — don‘t just pop-up out of the blue. It literally “takes a village” to grow one. Just like oral cavities respond to chewing tobacco hours on end with oral cancer, so does the colon respond with polyps and cancers to long-term assault of the large intestine with fiber, fermentation, large stools, straining, antibiotics and pollutants.

YOUR ACTION: Use Colorectal Recovery Kit to wean yourself from fiber dependence, to restore intestinal flora, to maintain small stools and to prevent straining. Give your colon health the same attention you are giving to cutting your hair and brushing your teeth. I‘ve yet to hear about “teeth cancer” or “hair cancer,” but people are dying from colorectal cancer left and right.

I realize the following two questions may be bugging you: (1) why aren‘t the complications described in this guide discussed with patients in advance of the screening? (2) Is it because doctors don‘t know?

I believe there are three factors behind this particular health scare:

Regardless of these reasons — some sinister, some stupid, some inadvertent to this situation — you now have the knowledge of what‘s causing them, how to avoid them and what to do about it.

What to do when you can't just say “no...”

In certain cases, colonoscopies are unavoidable, and, perhaps, life-saving. To protect yourself from unnecessary side effects, keep the following points in mind::

Dr_Whelch Should i be tested for cancer book coverFinally, If you are a physician or epidemiologist, and would like to get additional information about the perils of cancer (not just colorectal) screening, I recommend reading Dr. Gilbert Welch's book entitled Should I Be Tested for Cancer?  The answer to this question is quite self-evident from the subtitle: “Maybe Not and Here's Why!

Dr. Welsh — an ultimate insider — presents a good number of compelling reasons to explain why, in his own words “...cancer screening can do more harm than good”, and supports his analysis with detailed epidemiological data. 

According to Dr. Welch, the fear-mongering involved and risk of testing for other cancers are just as bad as for colon cancer. What else is new — where there is easy money to be made, victims are inevitable.

Author's commentaries

As you can see, a screening colonoscopy isn't the panacea it‘s purported to be. Be mindful of the risks; removing the causes of colon cancer should come first. And whether you do it or don't do it, it shouldn't be based on Ms. Couric‘s or my opinion, but on your doctor's weighted recommendation and/or risks factors discussed here.

Despite being well past 50, and in the high risk group for colorectal cancer, neither myself nor my wife Tatyana have ever been screened for colorectal cancer. We place more trust in functional nutrition and God's will than in “just in case” testing.

If and when we will take any test, we first must be darn sure that it's absolutely necessary. But as long as nothing hurts, we aren't into playing Russian roulette. I learned this rule a long time ago from an inside joke popular among physicians: “Should we treat him, or let him live?

It isn‘t as cynical as it may sound — medical doctors realize better than most that all medical procedures are inherently risky. Therefore, please don't interpret my analysis of screening colonoscopies as “Don't do it!”, but as “Don't overdo it!

Finally, if you do decide to get screened, at the very least you should restore intestinal flora after the procedure, as explained here. Otherwise you may be increasing your risk of developing new polyps and colorectal cancer long before the next screening is due in five or ten years, depending on your risk profile.



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The references for this guide were compiled in March 2008. Some of the links may not match at a later date because publishers may revise their web sites. In this case, try searching cached pages on Google, or contact the respective publishers.

1 Update on Colorectal Cancer; Am Fam Physician. 2000 Mar 15;61(6):1621-2, 1628 [link]

2 The Impact of a Celebrity Promotional Campaign on the Use of Colon Cancer Screening; The Katie Couric Effect; Archives of Internal Medicine, Vol. 163 No. 13, July 14, 2003 [link]

3Complications of Colonoscopy; Ann Intern Med. 2006 Dec 19;145(12):880-6 [link]

4 Assembly-line colonoscopies at clinic described; Las Vegas Sun, March 9, 2008 [link]

5 Whole Body Scanning Using Computer Tomography (CT); What are the Radiation Risks from CT; U.S. Food and Drug Administration, December 5, 2007 [link]

6 Virtual Colonoscopy Misses Nearly One Third of Lesions; The proceeds of the 68th annual scientific meeting of the American College of Gastroenterology; Oct 15, 2003 [link]

7 Irritable Bowel Syndrome; The National Digestive Diseases Information Clearinghouse, NIH Publication No. 07–693, September 2007 [link]