How is IBS diagnosed? Symptoms & Criteria [Plus IBS vs. IBD]

Table of Contents

Irritable bowel syndrome (also called IBS) is a common gastrointestinal disorder that impacts the large intestine, whose common symptoms include abdominal discomfort, abdominal bloating, and abnormal bowel habits.

How do you know you have IBS? Rome criteria dictate that, in order to diagnose IBS, a patient has to exhibit recurring abdominal pain for six or more months, as well as 2 of the following 3 symptoms:

  1. Pain or relief following bowel movements
  2. Change in frequency of bowel movements
  3. Change in consistency of bowel movements

According to the National Institute of Diabetes and Digestive and Kidney Diseases, around 12% of people suffer from IBS in North America. It is more common in women and people under the age of 50.

In this article, we cover how to diagnose IBS — as well as symptoms and treatments.

Done letting your gut issues rule your life? Join PrimeHealth’s Gut Health Group Visits and find lasting relief with a community of others who understand.
Sign up today — only a few spots remain for the next group beginning on Sept 20!

Common IBS Symptoms

What are the symptoms of IBS? Here are the most common symptoms of IBS:

  • Pain relief after defecation
  • The feeling of incomplete defecation
  • Increased urgency to defecate
  • Gas
  • Bloating
  • Cramping
  • Abdominal pain
  • Unintended weight loss
  • Mucus in stool
  • Rectal bleeding

Types of Irritable Bowel Syndrome

There are 2 main types of irritable bowel syndrome: IBS-C and IBS-D.

  1. IBS-C is irritable bowel syndrome with constipation (or constipation-predominant). This describes when your abnormal bowel habits result in fewer bowel movements or difficulty defecating.
  2. IBS-D is irritable bowel syndrome with diarrhea (or diarrhea-predominant). This describes when your IBS results in uncontrollable bowel movements.
  3. IBS-M is a third, less common type of IBS, which means “mixed” bowel habits IBS, combining elements of IBS-C and IBS-D.
  4. An uncommon fourth type of IBS is IBS-U, meaning “unclassified” IBS.

What’s the difference between IBS and IBD?

IBS stands for irritable bowel syndrome. It can present as diarrhea-predominant or constipation-predominant and only involves symptoms of the colon.

IBD stands for inflammatory bowel disease. IBD refers to a group of digestive diseases and can cause ulcers/lesions. Crohn’s disease and ulcerative colitis are the two most common examples of IBD. 

IBD is typically more severe and disruptive to daily life than IBS.

Tests Your Doctor May Perform to Diagnose IBS

Unfortunately, you cannot self-diagnose IBS. However, there are some online IBS diagnosis questionnaires that you can take to assess your current condition.

Nevertheless, these quizzes are never a substitute for a diagnosis from a doctor, as each IBS diagnosis and treatment plan is individual.

What is the process for diagnosing IBS? Although there is no one process for diagnosing IBS, there are some common starting points. A doctor may begin with evaluating your medical and family history, then with a physical exam and further testing to rule out other issues.

What are some tests that could be used to diagnose IBS? Tests that your doctor may use to diagnose IBS include:

  • Physical examination
  • Medical history
  • Family history
  • Colonoscopy
  • Sigmoidoscopy
  • Upper endoscopy
  • Blood tests
  • Stool tests
  • Celiac disease test
  • Lactose intolerance breath test
  • X-rays
  • CT scans
  • SIBO breath test

Though there is no one test to end all tests, the above is a standard array of medical tests to determine if you have IBS and why. There are so many different tests because there are multiple potential causes of IBS.

Your primary care physician may administer these tests, or they may refer you to a gastroenterologist.

Physical Examination

A physical examination is the most common test to diagnose IBS.

During a physical examination, your doctor usually checks for abdominal bloating, listens to your abdomen with a stethoscope, and checks your abdomen for any contact pain.

Your doctor may also examine your rectum for rectal bleeding, but this may also be done via a stool test or a medical history.

Medical History

Your doctor will ask about your medical history, including your recent symptoms.

Ideally, you will have been tracking your symptoms of IBS — perhaps with a simple diary or Notes app.

As long as you do not exhibit any “red flag” symptoms (rectal bleeding, fever, dizziness), identifying multiple IBS symptoms is often enough for many doctors to be confident in an IBS diagnosis without the need for further tests.

Some doctors may ask about antibiotic overuse. Overusing antibiotics can trigger leaky gut syndrome, SIBO, and yeast overgrowth, leading to all sorts of digestive diseases, such as IBS.

You may be asked about your drinking habits since excessive alcohol use has been linked with IBS. Smoking can also contribute to IBS.

A functional doctor can work with you to determine if you’re experiencing a hormone imbalance. When your hormones are out of whack, your bowels can suffer the consequences.

Functional doctors will almost certainly ask about chronic stress. About a third of American adults experience daily stress, which can lead to health problems like IBS.

Family History

Your doctor will probably ask you about your family’s medical history.

When diagnosing IBS, your provider will ask about a family history of:

  • IBS
  • IBD (such as Crohn’s disease or ulcerative colitis)
  • Celiac disease
  • Lactose intolerance
  • Other digestive diseases
  • Colon cancer

Functional doctors may also ask if your family has any history of chronic stress, leaky gut syndrome, or autoimmune disorders.


Can IBS be seen on a colonoscopy? No, a colonoscopy does not detect IBS. A colonoscopy rules out the potential alternatives to IBS, such as colon cancer (this requires a biopsy) or IBD.

Colonoscopies can determine whether you have polyps or tumors in your colon.


What is a sigmoidoscopy? A sigmoidoscopy is a procedure where your doctor uses a flexible tube to look in your sigmoid colon.

This procedure is one method to look for IBD, cancer, or intestinal polyps (abnormal growths). If any of these conditions are confirmed, you can rule out IBS.

Upper Endoscopy

An upper gastrointestinal endoscopy checks for celiac disease and gastric or intestinal ulcers.

At PrimeHealth, we also test for parasites that may be causing your IBS through stool testing. An endoscopy is one way to identify parasites.

Blood Tests

Does IBS show up in a blood test? IBS does not explicitly show up on a blood test. However, there are indicators in blood work that can point to infections, deficiencies, or antibodies that can signal the presence of IBS.

A medical professional will procure a blood sample from you and send it to a lab.

Doctors use these blood samples to determine if you have anemia, infection, parasites, or other medical conditions.

A few years ago, Dr. Mark Pimentel developed a two-blood test process called IBS Smart for diagnosing IBS related to recent food poisoning. These two blood tests identify the presence of two antibodies: anti-Cdtb and anti-vinculin.

Stool Tests

A medical professional will give you a container for catching a stool sample. You’ll probably take the test home. It comes with instructions on where to bring the test or where to send it.

Doctors use these stool tests to identify blood or mucus in stool, signs of infection, or the presence of parasites.

Functional doctors tend to use more in-depth stool testing than most conventional doctors. Common names for these tests are Genova GI Effects or Diagnostic Solutions GI Map.

These tests use DNA PCR analysis to investigate the various organisms present in the gut, like bacteria, yeast, and parasites. They also look at inflammatory markers, enzymes, short-chain fatty acids, the presence of fat or protein, and more.

Celiac Disease Test

You may need a celiac disease test to figure out if you have celiac disease triggering IBS.

Doctors usually test for celiac disease with:

What is the difference between IBS and celiac disease? One difference between IBS and celiac disease is that celiac disease only affects the small intestine, while IBS affects both the large and small intestines. Celiac disease is a gluten allergy, while IBS is a condition that impacts bowel movement.

Lactose Intolerance Testing

A hydrogen breath test can determine if you have lactose intolerance. An elimination diet can also help you figure out if you have an intolerance to milk proteins. During an elimination diet, you eliminate all dairy from your diet for at least a few weeks to see if your symptoms resolve.

Lactose intolerance may be the cause of your IBS. Cutting out dairy is a relatively straightforward (and inexpensive) treatment option, assuming this is the root cause of your IBS.


The use of x-rays is not common in the diagnosis of IBS. However, it can be helpful in some cases, mainly to rule out other causes.

X-rays can identify lesions caused by parasites, which can trigger IBS.

CT Scans

CT scan stands for computerized tomography scan. A CT scan uses special x-ray equipment to show a cross-section of internal organs.

In rare cases, a doctor may order a CT scan to look for digestive diseases that could rule out IBS.

SIBO Breath Test

Small intestine bacterial overgrowth (called SIBO) is usually present in IBS patients.

We have found SIBO testing to be very useful. We usually administer a SIBO breath test on our IBS patients.

Preparing for Your Doctor’s Appointment to Diagnose IBS

Here are 5 ways to prepare for a doctor’s appointment to diagnose IBS:

  1. Know your medical history.
  2. Know your family history. Call relatives ahead of time, if need be.
  3. Document any symptoms of IBS you experience.
  4. Keep a food diary.
  5. Write down any questions you have so you won’t forget.

Your doctor may instruct you whether to change your dietary habits before the appointment.

Mentally prepare for the potential of a physical exam, whether it may be a rectal exam or taking a stool sample. These diagnostic tests will be less uncomfortable if you have already accepted them as a possibility.

3 At-Home IBS Tests

Are there at-home self-checks for IBS? Yes, there are at-home IBS tests, but they aren’t the best. The most accurate test would be to procure a diagnosis from a medical professional.

Nevertheless, here are 3 at-home self-checks for IBS:

  1. Candida spit test: This one is gross, but it has some merit. To test for Candida overgrowth, which often accompanies IBS, spit into a glass of water — first thing in the morning. If it floats for 45 minutes, you’re golden. If it sinks or forms legs, you may have an overgrowth of Candida yeast.
  2. Food allergy pulse test: Also called the Coca Pulse Test, this one takes patience. Check your pulse, put food in your mouth for 30 seconds without chewing, then recheck your pulse. If your pulse rises 6 points, you may be allergic to that food.
  3. Low stomach acid test: First thing in the morning, drink ¼ teaspoon of baking soda in 4-6 ounces of chilled water. Try to burp. If it takes longer than 3 minutes to burp, you may have low stomach acid, which can lead to digestive issues like IBS.

Another self-check is identifying when you are particularly stressed and checking if your IBS acts up when that stress appears. Stress can cause bowel disorders.

A Functional Approach to IBS Treatment

These are the most effective IBS treatments we recommend:

  • Dietary changes – to find the diet that works for your body, join our online 6-week Elimination Diet
  • Lifestyle changes
  • Certain medications

Dietary Changes

Making changes in your diet will be helpful to your overall health, as well as to your IBS symptoms. Here are the 2 shifts that we recommend.


FODMAPs are foods well-known to trigger digestive health problems. FODMAP stands for “fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.”

On a low-FODMAP diet, you avoid these foods:

  • Wheat
  • Rye
  • Dairy products 
  • Beans
  • Garlic, onions (contain fructans)
  • Fruit (because of fructose)
  • Asparagus
  • Brussels sprouts
  • Cauliflower
  • Mushrooms
  • Snow peas
  • Agave nectar
  • Sugar alcohols

The low-FODMAP diet is not meant to last very long — no more than a few months. The low-FODMAP diet is not recommended during SIBO treatment. The anti-SIBO antibiotics are actually more effective when you eat high-FODMAP foods.

This diet is also typically not appropriate during pregnancy, as it may lead to limited caloric or nutrient intake vital to a developing fetus.

Dietary Probiotics

Dietary probiotics for IBS are great for restoring the balance of good bacteria to your gut. Probiotics are simply “good” bacteria — the microorganisms that your body needs to function properly. 

Unfortunately, antibiotic overuse and other bad habits can lead to an imbalance of bacteria in your gut. This imbalance can cause leaky gut syndrome, another trigger of IBS.

Fortunately, probiotics can return your gut to its former glory. Probiotics have been shown to improve IBS symptoms in countless scientific studies.

Some of the best sources for dietary probiotics are:

  • Pickles
  • Miso
  • Yogurts
  • Sauerkraut
  • Kombucha
  • Kimchi

However, use caution when using probiotics. Many probiotic foods can be FODMAPs. Also, probiotics may not work if you’re suffering from SIBO because the good bacteria get stuck in your small intestine before making it to the large intestine, where it needs to go.

If you’re struggling to fit in fermented food, probiotics are also available as supplements.

Lifestyle Changes

There are 4 lifestyle changes that may help with IBS:

  1. Stress relief is an effective method of lowering your risk of IBS. Meditation, yoga, a full night’s sleep, and spending time in the outdoors are all great ways to get rid of stress. Avoiding blue light exposure can be very helpful for getting a good night’s rest. To receive 10% off of our favorite blue light blocking glasses by Ra Optics, enter code PRIMEHEALTH at checkout.
  2. Exercise may lower the risk of IBS. Studies show that physically active people are significantly less likely to exhibit IBS symptoms than inactive people.
  3. Intermittent fasting might relieve your IBS symptoms. If you’re eating too much too quickly, your digestive tract can’t properly process what you’re eating. Fasting in the mornings or evenings may fix the problem. Start with a fasting window of 12 hours, then slowly work your way to a 16-hour break between dinner and the following breakfast.
  4. Time between meals without snacking of at least 4 hours can also be helpful, as your body needs at least 4 hours without food to activate emptying via peristalsis. The nerves responsible for peristalsis in the small intestines are called the migratory motor complex.


We might prescribe our patients several medications, especially if they aren’t responding to dietary and lifestyle changes. Remember that many of the medicines listed below are meant to treat short-term symptoms and are not a cure for IBS.

  • Rifaximin and Xifaxan are antibiotics that treat IBS-D and IBS-C. Many insurance companies won’t pay their high price tags, so we utilize pharmacies in Canada where the prices are much more reasonable.
  • Neomycin is an antibiotic we might prescribe for IBS-C along with rifaximin.
  • Metronidazole and tinidazole are antiparasitic antibiotics that we may prescribe if the patient has parasites.
  • Lubiprostone is a laxative that some doctors prescribe for IBS-C.
  • Prucalopride is a promotility medication that helps activate the migratory motor complex and peristalsis.

You can get IBS medication over the counter as well:

  • Loperamide (Imodium) helps control diarrhea.
  • Dicyclomine (Merbentyl) is an antispasmodic, which means it relaxes your gut muscles.
  • Bismuth subsalicylate (Pepto-Bismol) is an antacid that treats indigestion and diarrhea.

Biofilm disruptors, like Interfase Plus, may be necessary to fight harmful bacteria that form a protective biofilm.

Some health care providers may suggest the use of tricyclic antidepressants such as imipramine, amitriptyline, or nortriptyline for the temporary treatment of IBS. 

However, side effects of an SSRI or tricyclic antidepressant include constipation, blurred vision, dry mouth, and even suicidal thoughts in vulnerable patients. These side effects must be balanced with their impact on IBS symptoms.

Painkillers only treat the symptoms of IBS instead of the root cause. However, relieving pain and inflammation in your digestive tract can offer short-term improvement to your quality of life while you address the underlying cause.

Here are some all-natural painkillers that don’t come with those nasty side effects:

  • Ginger
  • Oregano oil
  • Peppermint oil
  • Rosemary oil
  • Capsaicin
  • Feverfew

How to Cure IBS in One Day

For some, what triggers IBS can be resolved in a single day. If your IBS is triggered by something simple, this checklist may help cure your IBS in one day.

  1. Avoid gassy foods like beans, brussels sprouts, carbonated beverages, and caffeine.
  2. Avoid gluten and lactose. Not only do these common allergens cause inflammation that could lead to IBS, but you could have a food sensitivity and not know it.
  3. You may be eating too much or too little fiber. Adjust your fiber intake and record your improvement or otherwise.

Don’t be fooled by anyone telling you to take honey for IBS. We’ve debunked that “remedy.”

Unfortunately, most peoples’ IBS symptoms won’t resolve in one day. But these are easy first steps to determine whether you need to see a doctor.

Looking to an IBS-Free Future

Irritable bowel syndrome is treatable. Our patients prove it. There is hope.

You may have to make simple changes to your lifestyle or diet, but IBS is not a permanent disease.

Our functional approach to IBS treatment is supported by research and our patients who have recovered. When you think about your future, IBS does not have to be a part of it.

Stop Googling and finally get to the root of your gut issues.
Our gut health group visits begin Sept 20, 2022. Don’t miss out — sign up today!

— Medically reviewed by Soyona Rafatjah, M.D. on April 19, 2021


  1. Chey, W. D., Kurlander, J., & Eswaran, S. (2015). Irritable bowel syndrome: a clinical review. Jama, 313(9), 949-958. Full text:
  2. Lacy, B. E., & Patel, N. K. (2017). Rome criteria and a diagnostic approach to irritable bowel syndrome. Journal of clinical medicine, 6(11), 99. Full text:
  3. Patel N, Shackelford K. Irritable Bowel Syndrome. [Updated 2020 Jan 3]. Irritable Bowel Syndrome. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Full text:
  4. Reding, K. W., Cain, K. C., Jarrett, M. E., Eugenio, M. D., & Heitkemper, M. M. (2013). Relationship between patterns of alcohol consumption and gastrointestinal symptoms among patients with irritable bowel syndrome. The American journal of gastroenterology, 108(2), 270. Full text:
  5. Qin, H. Y., Cheng, C. W., Tang, X. D., & Bian, Z. X. (2014). Impact of psychological stress on irritable bowel syndrome. World journal of gastroenterology: WJG, 20(39), 14126. Full text:
  6. Pimentel, M., Morales, W., Rezaie, A., Marsh, E., Lembo, A., Mirocha, J., … & Barlow, G. M. (2015). Development and validation of a biomarker for diarrhea-predominant irritable bowel syndrome in human subjects. PLoS One, 10(5). Full text:
  7. Dale, H. F., Rasmussen, S. H., Asiller, Ö. Ö., & Lied, G. A. (2019). Probiotics in Irritable Bowel Syndrome: An Up-to-Date Systematic Review. Nutrients, 11(9), 2048. Full text:
  8. Hirotsu, C., Tufik, S., & Andersen, M. L. (2015). Interactions between sleep, stress, and metabolism: From physiological to pathological conditions. Sleep Science, 8(3), 143-152. Full text:
  9. Thompson, C. W., Roe, J., Aspinall, P., Mitchell, R., Clow, A., & Miller, D. (2012). More green space is linked to less stress in deprived communities: Evidence from salivary cortisol patterns. Landscape and urban planning, 105(3), 221-229. Full text:
  10. Johannesson, E., Simrén, M., Strid, H., Bajor, A., & Sadik, R. (2011). Physical activity improves symptoms in irritable bowel syndrome: a randomized controlled trial. American Journal of Gastroenterology, 106(5), 915-922. Abstract:
  11. Chung, M. K., & Campbell, J. N. (2016). Use of capsaicin to treat pain: mechanistic and therapeutic considerations. Pharmaceuticals, 9(4), 66. Full text:

Share this Post