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Get Your IBS Diagnosis!

Before you start to become your own digestive detective, it's very important that you get your IBS diagnosis from your doctor.  IBS symptoms can be caused by other conditions, some of them more serious.  So please don't self-diagnose!

In this section you'll find out more about the Rome IV diagnostic criteria for IBS and tests that might be performed to rule out other causes of your symptoms

To make things easier for you when you speak with your doctor, I've provided a checklist to help you prepare for your appointment.

To find out more about getting your IBS diagnosis...

  • Watch the video

  • Click links in the white box

  • Just scroll down!

The IBS Diagnosis

Dr.'s clipboard and stethascope

In the past IBS was known as a diagnosis of exclusion, or the diagnosis given when all other possible causes had been ruled out.  Doctors would often run many tests, some of them invasive.

Now the push is to make IBS a more positive diagnosis.  After taking your medical history and a physical examination, your doctor will compare your symptoms to the Rome IV Criteria for IBS and some common tests may be done.

If your symptoms match the Rome IV Criteria for IBS and you don't have symptoms that aren't normal for IBS or any red flags, there is a very good chance you'll receive your IBS diagnosis at this point.

If your symptoms don't match the criteria or you have any red flags, your doctor may run further tests to rule out more serious causes of your digestive issues.

The Rome IV Diagnostic Criteria for IBS

The Rome Criteria for the diagnosis of IBS were developed by a panel of international experts in the field of functional GI disorders.  Functional disorders are those where physically everything seems fine, but there is a problem with the way the body functions.

Rome I was created in 1992, a few years after a panel of experts met in Rome to begin developing criteria for diagnosing IBS.  Criteria are standards used to judge or decide something.  Instead of IBS just being what was left over after everything else had been ruled out, the expert panel created a list of symptoms to define IBS.  The criteria have been changed over the years to reflect ongoing research.  

Roman columns

Rome IV Diagnostic Criteria for IBS (2016) 

Recurrent abdominal pain on average at least 1 day per week in the last 3 months, associated with 2 or more of the following criteria:

1. Related to defecation

2. Associated with a change in frequency of stool

3. Associated with a change in form (appearance) of stool

*Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis

  • IBS diagnosis includes belly pain and changes in your bowel movements (pooping)

  • Pain is related to pooping, which means it could ease up or get worse

  • It's normal to poop anywhere from 3 times a day to 3 times a week.  The doctor will be looking for changes from your normal routine.

  • The Bristol Stool Chart is usually used to describe the form or appearance of your poo

  • IBS symptoms can flare up and then ease off, but for a diagnosis they should have started at least 6 months ago and have been ongoing for the last 3 months give or take.

IBS Sub-Types

IBS is categorized based on the most common type of poo you have.  This is helpful when deciding which tests and treatments are best.  IBS symptoms can change over time, so it's possible you may experience different subtypes over your lifetime.

IBS - D    Diarrhea more that 25% of the time

IBS - C    Constipation more than 25% of the time

IBS - M  Diarrhea more than 25% and constipation more than 25% 

IBS - U  Diarrhea/constipation less that 25% of the time with symptoms                             

Bristol Stool Chart

*Be sure to tell your doctor if you are taking any medications, supplements or herbal remedies to treat constipation or diarrhea, as this can affect your classification.

Symptoms Associated with IBS

GI Symptoms:

  • Abnormal BMs (less than 3x per week or more than 3x per day)

  • Change in bowel movements (BMs) – constipation, diarrhea or mixed

  • Distension (you can see an increase in the size of your belly)

  • Bloating (feeling like there is an inflated balloon in your belly)

  • Urgency or feeling like you suddenly have to go right now

  • Feeling like you haven’t completely emptied your bowels 

  • Straining when trying to poop

  • Mucus in your stool

  • Belly pain

  • Lots of gas

  • Cramps

Other Symptoms:

  • Back pain

  • Lack of energy (fatigue)

  • Difficulty sleeping

  • Feeling sick (nausea)

  • Anxiety and/or depression

  • Problems peeing - needing to pee often, sudden urges or feeling like you can't completely empty your bladder

Man with anxiety and depression
Man running to the bathroom

Common Tests

Celiac Disease Screening

International guidelines recommend screening for celiac disease because of the large overlap of symptoms, especially in the case of IBS - D or IBS - M.  Other experts feel the test is not necessary, so speak to your doctor if you have any concerns.

Celiac disease is an immune disorder that actually damages the small intestine and is triggered by eating gluten. It could lead to nutrient deficiencies or some types of cancer.


Doctors diagnose celiac disease with blood tests, biopsies (tissue samples) of the small intestine, skin biopsies, and genetic tests.  It's important to let your doctor know if you've been following a gluten free diet, as this will affect some test results.

Lactose Intolerance

Lactase is an enzyme that helps you digest the sugar found in dairy products.  If your body does not produce enough lactase, you may have problems similar to those caused by IBS - belly pain, gas and diarrhea.

Your doctor may order a breath test or ask you to stop eating milk and milk products for a few weeks

Wheat with an X across - no gluten
Dairy products with a line across - no lactose

Blood Tests

You may not have these tests if your symptoms match the Rome IV criteria for IBS and you have no warning signs.  If your doctor suspects there might be another cause, they may start here.

Complete Blood Count (CBC)

Used to rule out infections or other conditions that may be causing your digestive symptoms

C-Reactive Protein (CRP)

Used to rule out conditions with inflammation.  If you have IBS, this test usually has a normal result.

Erythrocyte Sedimentation Rate (ESR)

Measures the amount of inflammation in the body and used to detect cancer or inflammatory diseases.  If you have IBS, this test usually has a normal result.

blood test ibs

Other Possible Causes of IBS Symptoms

Medical tests

This section is not meant to alarm you, but rather to educate and prepare you for your doctor's appointment.  Nobody wants to have a serious health issue, but if you do it's best to know sooner than later so you can receive the proper treatment.

Some conditions have some symptoms that are similar to those of IBS (like celiac disease) and your doctor may want to run tests to rule them out.  You might be referred to a gastroenterologist, a digestive system specialist.  Depending on your symptoms you may receive other tests, but the following are the most common.  


And not to worry if you don't receive any of the following tests.  Testing is expensive, invasive and can cause anxiety, so your doctor will probably order tests on the basis of your reported symptoms, family history of disease and red flags.  Be sure to ask your doctor if you have any concerns.

Red Flags

Red flags are warning signs your symptoms don't match the criteria for IBS and that something else may be causing them.

Common red flags include:

  • Unexplained weight loss

  • Over 50 years old when symptoms start

  • Family history of celiac disease, inflammatory bowel disease (Crohn's or ulcerative colitis), colorectal cancer, diverticular disease, endometriosis or ovarian cancer

  • Anemia

  • Fever

  • You are very tired all the time

  • Pain not related to bowel movements

  • You throw up regularly

  • Bleeding from the rectum or blood in your poo

  • Diarrhea everyday that won't go away

  • You have to poo in the middle of the night

  • Fecal incontinence (can't control bowel movements)

  • Symptoms came on suddenly and keep getting worse

  • Hard lump or swelling in belly

  • Anal abscesses or fistulas 

  • Non GI symptoms like a rash or eye inflammation

red flag

Inflammatory Bowel Disease (IBD)

IBS is describes two conditions - Crohn's disease and ulcerative colitis.  Both involve chronic inflammation of the GI tract that can eventually damage the intestines.

If there is blood in your poo or other symptoms that might indicate IBD, your doctor may order a fecal calprotectin test.  This is a protein that is present in high levels if there is inflammation in your bowel and you will have to provide a poo sample.  

If further investigation is needed, you may have a colonoscopy.  A flexible tube with a camera attached is inserted into the rectum and up into the colon to look for abnormalities.  A tissue sample might also be taken, which is called a colonic biopsy.

Large enflamed intestine - IBD

Colorectal Cancer

This is cancer of the colon or rectum, also called bowel cancer.  One option for screening is the fecal occult blood analysis.  This test used to detect tiny amounts of blood from pre-cancerous polyps or early stage cancer and require two separate poo samples.


You may also be referred for a colonoscopy and a colonic biopsy. 

Inside of intestine with cancerous growths - colorectal cancer

Ovarian Cancer

Some symptoms of ovarian cancer are similar to IBS symptoms, like bloating and changes in bowel habits.  It usually occurs in women over 50, but can happen to younger women.  The sooner ovarian cancer is detected, the easier it is to treat.

If your doctor suspects you have ovarian cancer, they will probably order a simple blood test and then go from there.

Woman's reproductive organs - ovarian cancer

Diverticular Disease

Small bulges or pockets develop in the lining of the intestine.  Diverticulitis occurs when the pockets become inflamed or infected.

If you doctor suspects you may have diverticular disease, you could have blood tests, poo tests, a colonoscopy or imaging tests like a CT scan or an MRI.

Intestine with pockets - diverticular disease


Disease in which tissue similar to the lining of the uterus grows outside the uterus.  The main symptom is severe pain in the pelvis and it can make it harder to get pregnant.  Symptoms can be very different from person to person, just like IBS, and it might not be easily diagnosed.

At the present time there are no tests to screen for the condition.  A careful history of symptoms during your period and of chronic pain in your pelvis might lead your doctor to suspect you have it.  Imaging tests like an MRI or a surgical procedure could confirm the diagnosis.

Many symptoms of endometriosis overlap with IBS:

  • Pain in lower belly (pelvis)

  • Pain during bowel movements

  • Belly bloating, constipation nausea, fatigue

  • Sometimes anxiety or depression

So be sure to tell you doctor if you also have:

  • Severe pain during periods, sex, bowel movements or peeing

  • Chronic pain in your pelvis (all the time)

  • Heavy bleeding during or between periods

  • Irregular periods

  • Trouble getting pregnant

Woman holding image of reproductive organs - endometriosis

Small Intestinal Bacterial Overgrowth (SIBO)

Too many or the wrong kind of bacteria build up in the small intestine and can affect the absorption of nutrients.  This can cause GI symptoms in the short term and nutritional deficiencies in the long term.  It is more common if you've had bowel surgery or another condition that slows down digestion.

Breath tests to measure hydrogen and/or methane gas produced by the bacteria may be done, but the tests aren't very reliable.  Other possible tests include blood tests for vitamin deficiencies, poo tests for undigested fats or imaging tests for structural problems.

SIBO and IBS share many symptoms - belly pain and distension, nausea, bloating, gas, diarrhea, constipation and fatigue.  It is even possible to have both and IBS may help to cause SIBO.  Tell your doctor if you have experienced unexplained weight loss, as this  is a symptom of SIBO, but not of IBS.  Nutrient deficiencies may also be present in SIBO.

Intestines with magnifying glass showing bacteria - SIBO

Food and Chemical Intolerances

Although symptoms of a food or chemical intolerance are often very similar to those of IBS, if you are intolerant to something you only develop symptoms after eating that particular thing.  Intolerances are not connected to the gut/brain axis in the same way as IBS.  Intolerances are also different from allergies, because they do not involve the immune system.  

Food Intolerances

Symptoms of food intolerances are most likely caused by problems digesting or absorbing certain foods or components of foods in the GI tract.  Unlike allergic or chemical reactions where a small amount of food can cause a reaction, it usually takes a more normal size portion to cause symptoms.

Lactose intolerance was already discussed in the Common Tests section.  Fructose malabsorption is another more common intolerance and occurs when the cells of your intestine can't absorb fructose properly.  Symptoms are gas, bloating, diarrhea and pain.  The test for fructose malabsorption is a breath test, but the reliability of the test is very questionable.

honey fructose_edited.jpg

Food Chemical Intolerances

Some sources don't differentiate between food and chemical sensitivities, as all food compounds have a chemical composition.  For our purposes chemical intolerances occur when a person has a bad reaction to chemicals that occur naturally in or are added to foods and a small amount could cause a reaction.

Some examples of more common food chemicals that can cause IBS like symptoms are:

  • Amines - found in fermented foods (e.g. blue cheese, wine).  Histamine is an amine.

  • Salicylates - naturally occurring organic acid found in many foods, also in aspirin.

  • Glutamates - occur naturally, also food additives like MSG.

Not a lot is known about the cause of food chemical intolerances and there is no test to rule  them out.  There is an elimination and reintroduction diet called Fail Safe that could help to pinpoint a food chemical sensitivity, but it should be done under the supervision of a trained dietitian.

Contains additives_edited.jpg

Bile Salt Malabsorption
(aka Bile Acid Malabsorption or BAM)

Bile salts are one of the main components of bile, which helps to break down fats in the small intestine.  Normally the bile salts are reabsorbed, but if not the leftover bile enters the large intestine.  This causes water to be pulled in causing diarrhea and other IBS symptoms.

Research is now showing that bile salts do much more than break down fats and are being linked to other complex functions like intestinal motility and to other systems including the gut microbiome.  More research is needed, but it may turn out that this is an underlying cause of some IBS cases instead of a completely separate condition.

Testing is not routinely done.  If you are in Europe you may receive a nuclear medicine scan, otherwise a poo test or blood test might be done.

Gall bladder with bile salts

Pelvic Floor Disorders

These occur when the muscles of the pelvic floor don't work properly and can lead to constipation, incontinence or the ability to hold in your poo, problems with peeing and issues with sexual intercourse.

The causes are not well understood.  It's possible that if you've been living with IBS-C for a long time, you may have done some damage to your pelvic floor as a result of your symptoms.  It could also be that IBS sufferers could have an issue with their pelvic floor that may not get recognized because symptoms are seen as a result of their IBS.

If your doctor suspects pelvic floor dysfunction, they may start with a history of symptoms and a physical examination.  They may order other tests or refer you to a physiotherapist.

Pelvic floor

Hyper and Hypo Thyroidism

Thyroid conditions can affect digestion, either slowing down or speeding up the movement of food through the digestive tract leading to diarrhea or constipation.

The thyroid function test is a blood test that checks thyroid hormone levels.


Problems with the Pancreas

The pancreas plays an important role in the digestion and can affect it in many ways, including exocrine pancreatic insufficiency.  This means that you don't have enough enzymes for your digestive functions.  Some symptoms overlap with IBS, but there are warning signs that are not part of an IBS diagnosis.

If your doctor suspects you have problems with you pancreas, you may be sent for breath, blood or poo tests.


Your Doctor's Appointment

Doctor holding clipboard

You've made your doctor's appointment.  Good for you!

It's common to be nervous at the doctor's office and forget things you meant to say or questions you meant to ask. The more you have to tell your doctor about your symptoms and family the history, the easier it will be to make a diagnosis or decide on further testing.  Filling out the Doctor's Appointment Checklist is a great way to get prepared. 


Even though the medical community has started taking IBS more seriously, you may still encounter medical professionals who hesitate to give you an IBS diagnosis or try to brush you off by saying ,"It's just IBS". 


Sometimes you have to advocate for your own healthcare, so remember that IBS is a real condition with a real impact on your quality of life.  The sooner you get your IBS  diagnosis, the sooner you can start to become your own digestive detective and find the strategies that work for you.

IBS and Quality of Life

IBS is a real condition with very real impacts on your quality of life.

These are just some of the ways that IBS can affect your life and relationships.

Be sure to let your doctor know how your symptoms are affecting you and don't let anyone dismiss you by saying, "It's just IBS".

Infographic - impact of IBS on quality of life

Doctor's Appointment Checklist

Dr.'s appointment checklist

Get prepared for your doctor's appointment with the following checklist. You can download the checklist and fill it in if you are using a desktop or laptop.


Keeping a food and/or symptom diary will be helpful for both you and your doctor, so best to get started on that right away if you can.  For a refresher of possible IBS symptoms 

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