Do you often find yourself scrambling to find a bathroom at the worst possible moment? Do you get anxious about traveling because you worry that your constipation will act up? Or maybe you try not to stray too far from home at all, for fear that you won’t find a bathroom? If so, you are not alone. Irritable Bowel Syndrome (IBS) is the most common functional gastrointestinal (GI) disorder. In fact, studies estimate that 38-96 million Americans suffer from IBS,2 although only 5 to 7% have been diagnosed.3 Symptoms of IBS include frequent diarrhea, constipation—or both—gas, bloating, and abdominal pain.

IBS is defined by a group of symptoms including abdominal pain or discomfort and changes in bowel movement patterns. Doctors call IBS a “functional gastrointestinal disorder.” This means that the GI tract doesn’t function properly, yet does not show any physical damage.

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The IBS Diagnosis

In reality, IBS is a diagnosis of exclusion, meaning a patient has had extensive lab testing, studies, and procedures done, but everything comes back normal. When doctors are unable to identify a diagnosable condition that would explain your condition, you’re “diagnosed” with IBS. Because of this, conventional medicine focuses on managing the symptoms of the disease, usually with potent immunosuppressive medications and invasive surgeries. Both of these can have significant side effects that impact your gut health. They may kill off the good bacteria that live there, increasing intestinal permeability, and causing leaky gut. I’ll get into that later on. 

In Functional Medicine, however, we know that IBS isn’t just uncomfortable and potentially embarrassing, it is a sign that something is awry in your gut. We also know that treating the symptoms while leaving the underlying cause untreated can lead to even more serious problems, including an autoimmune disease.

What causes IBS?

So, what exactly causes IBS? The answer depends on the individual. Because IBS is not a single disease with a single cause, but rather a complex collection of symptoms, it has several possible definitions. And while it isn’t officially classified as an autoimmune disease, it shares some of the same risk factors of autoimmunity, including leaky gut, food sensitivities, toxins, infections, and stress, as well as an underlying inflammatory condition.

The Difference Between Causes of IBS and IBS Triggers

IBS triggers are factors such as food and stress that can cause your IBS symptoms to flare. Luckily, by making diet and lifestyle changes, you can learn to recognize and avoid your triggers in order to temporarily relieve your discomfort. However, as I mentioned above, IBS is often a sign of a larger underlying issue; many of my patients with autoimmune or thyroid conditions experienced IBS as a symptom of those conditions. Addressing the root cause of your IBS is the key to finding relief from your symptoms and reversing your condition.

IBS Causes

The latest research, as well as my own clinical experience, suggests that in most cases, there are five main underlying causes of IBS. People with IBS may have any one of these factors, or a combination of them. A functional medicine doctor can help you identify the specific cause (or causes) of your individual IBS symptoms.

Leaky Gut

The healthy GI tract serves as a barrier that prevents undigested food particles, microbes, toxins, and other undesirable substances from entering the body through the bloodstream. When the cells lining the intestinal wall become damaged, they break apart, allowing these substances to “leak” into the body, where they are treated as “foreign invaders” by the immune system. The immune system launches an attack to rid the body of these invaders, and inflammation can result. Studies have shown a link between IBS and leaky gut.4 Fortunately, leaky gut syndrome can be treated with a comprehensive elimination diet and a 4R program.

Small Intestinal Bacterial Overgrowth

The symptoms of IBS are similar to those of Small Intestinal Bacterial Overgrowth (SIBO), which can include gas, bloating, and diarrhea. SIBO occurs when the bacteria in our gut get out of balance and overgrow. In one study, nearly 80% of people with IBS were found to have SIBO. When the SIBO was treated, nearly half of the patients experienced improvement in their IBS.5 If you suspect that SIBO may be the underlying cause of your IBS, you can ask your doctor to order a SIBO breath test. This test will determine if SIBO is present, and will also provide helpful information indicating what treatment protocol will be most effective. Treatment for SIBO includes a 4R program, a low-carbohydrate diet, and prescription Xifaxan or Microb-Clear.

Yeast Overgrowth

Because yeast feeds on sugar, the treatment for Candida overgrowth includes a low-carbohydrate diet, anti-fungal supplements specific to yeast, and probiotics to restore your gut’s natural balance. You can treat your yeast overgrowth at home using The Myers Way® Candida Breakthrough Program®, a complete 30-day program that includes a meal plan, supplement regimen, recipe book, shopping lists, and a guided email series.


Intestinal parasites including Giardia lamblia, Blastocystis hominis, Dientamoeba fragilis, may be a common cause of IBS, and they often are undiagnosed. I routinely screen my IBS patients for intestinal parasites with a comprehensive stool test. But before I help them clear the infection, I assess whether or not the parasite is a) directly harmful, or b) potentially beneficial. While parasites can be the cause of IBS and ulcerative colitis, in Crohn’s disease, certain types of parasites can actually be helpful. It is important to assess your case individually with your functional medicine doctor. If a parasite is contributing to your IBS, there are prescription medications specific to certain species of parasites that can be used. Or, if the species of parasite cannot be identified, I recommend Microb-Clear, which provides a broad spectrum of activity against the most common pathogens present in the human GI tract, while sparing the beneficial gut bacteria.

Food Allergies or Sensitivities

Food allergies or food sensitivities typically present with symptoms including gas, bloating, abdominal pain, and changes in stool frequency and consistency, much like those of IBS. In food sensitivities, which cause IgG or delayed immune responses, it can take up to 72 hours for symptoms to appear, making the cause difficult to pin down. In addition to the most common food allergies, such as peanuts, I find that gluten, dairy, corn, soy, and eggs are common food sensitivities that irritate the bowel and digestive system, leading to IBS-like symptoms.

To identify foods that might be causing your IBS symptoms, as well as other symptoms that you might have thought were unrelated to your digestive distress, I recommend completing a comprehensive elimination diet. The program will remove all common inflammatory foods from your diet and then reintroduce them one at a time so that you can determine any food sensitivities.

What Triggers IBS?

As I mentioned above, IBS triggers are factors that aggravate your IBS symptoms. IBS triggers vary from person to person. Learning to recognize your personal triggers is a great way to manage your IBS while you work to find the root cause. 

Diet IBS Triggers

Certain foods are common triggers for many people with IBS. Dairy is one of the main causes of IBS flare-ups in people who don’t produce the lactase enzyme, which allows you to break down lactose found in milk into simple sugars. The lactose travels undigested into your colon, where bacteria may begin to ferment it, creating gas. In a similar way to gluten, this leads to inflammation and poor digestion of both lactose and the foods you eat while your gut is inflamed. 

If you aren’t lactose intolerant, you might still react to the two proteins found in milk: casein and whey. Casein is a protein with a very similar molecular structure to gluten and 50% of people who are gluten intolerant are casein intolerant as well. As with gluten, I recommend everyone avoid dairy, especially if they are concerned about IBS.

Additionally, certain sweeteners such as sorbitol and fructose produce digestive distress in some people, as does too much fat. A low-FODMAP diet can be helpful for people who struggle with SIBO, IBS, and other gastrointestinal disorders and symptoms while they get to the root cause of the problem. Try an elimination diet to determine which foods are triggering your IBS symptoms.

Stress IBS Triggers

Many IBS patients notice that their symptoms become worse as their stress increases, and studies have shown a link between higher stress levels and increased rates of IBS.6 This is because your brain and your gut are connected by your central nervous system via the vagus nerve. If you have a low vagal tone, and experience stress, your body’s stress response can cause your colon to contract too much or too little (causing constipation or diarrhea). this works the same way, for example, that stress can cause your heart rate to increase and your blood pressure to rise.

Interestingly, the connection shared between your gut and your brain is actually a two-way connection. Your brain sends signals to your gut, but your gut produces key neurotransmitters that your brain uses to regulate mood. In fact your gut produces 95% of your serotonin, a neurotransmitter that regulates mood and sleep. This means that gut issues can impact your serotonin levels, causing you to actually experience more stress, which can in turn affect your IBS.

Anxiety IBS Triggers

Another mental state that can affect gut health is anxiety. In fact, an estimated 40-60% of those with IBS have a psychiatric disorder such as anxiety or depression. When you feel anxious, your body releases stress hormones including cortisol, which affect both your digestive system and your immune system. 

Unfortunately, most of us experience prolonged periods of anxiety and stress, leading to chronic bouts of IBS symptoms that seem to linger in the background of our lives. Learning to recognize situations that will put you in a state of anxiety or stress can help you prevent triggering your IBS symptoms. I’ll discuss ways to reduce stress in a bit.

Medication IBS Triggers

If optimizing your diet or reducing your stress and anxiety isn’t helping to alleviate your IBS symptoms, it might be a good idea to consider any medications you’ve taken recently. With the use of many common prescription and over-the-counter (OTC) medications, you could be compromising your gut health without even knowing it, contributing to your IBS symptoms.

One of the most notable culprits is NSAIDs — which include aspirin, ibuprofen, and naproxen — which can cause both diarrhea and constipation. Another group of medicines to consider is antidepressants. However, given the connection between mental health issues and IBS, some people who also have depression or anxiety may benefit overall from remaining on these types of medications.

For those who are seeking healthy alternatives to their medications, Omega-3 fish oil and curcumin are great options to support a healthy inflammatory response without all the harsh side effects.

Other IBS Triggers

Other lifestyle factors such as not getting enough quality sleep, consuming too much caffeine or alcohol, and a constantly changing routine can be IBS triggers for some people.

Because each person experiences IBS differently, it’s useful to keep track of your symptoms and possible triggers. For example, keeping a diary of what you’re eating, how much, when, and how fast, in addition to how much you’re sleeping and whether it’s interrupted throughout the night is a great way to start identifying your triggers. Write about your emotional state and your stress levels, including events that make you feel anxious or excited. Travel is also an important detail as it means a change in routine. 

After a period of time, you’ll hopefully notice a pattern and be able to easily identify and avoid your triggers until you find the root cause of your IBS.

The Myers Way® Approach to Irritable Bowel Syndrome

Establishing the underlying cause of the irritable bowel syndrome for each patient allows me to choose the most effective treatment strategy. For most people with IBS, conventional medicine treats the symptoms of the disease—usually with potent immunosuppressive medications and invasive surgeries—while ignoring the underlying causes that led to the inflammation in the first place.  Whether the cause is due to leaky gut, small intestinal bacterial overgrowth, yeast overgrowth, food allergies or intolerances, stress, or some other factor, the key to overcoming your IBS symptoms is to heal your gut using my 4R Program.

I have seen thousands of patients recover from IBS and other digestive problems by implementing the 4R approach.

The 4R Program

  1. Remove. Remove the bad, getting rid of things that negatively affect the gut, including inflammatory foods such as gluten, dairy, corn, soy, eggs, and sugar, infections from parasites, yeast, or bacteria, and irritants such as alcohol, caffeine, and drugs.
  2. Replace. Replace the good, adding back the enzymes and acids required for proper digestion.
  3. Reinoculate. Restore a healthy balance of good bacteria by reintroducing beneficial bacteria through a high-quality, multi-strain probiotic supplement.
  4. Repair. Provide the nutrients necessary to help heal your gut. My most comprehensive weapon against leaky gut is Leaky Gut Revive® powder, which contains powerful gut-repairing ingredients l-glutamine, aloe, deglycyrrhizinated licorice, arabinogalactan, slippery elm and marshmallow root. With these ingredients, Leaky Gut Revive™ nourishes and soothes your gut cells, restores your gut’s natural mucosal lining, and maximizes gut-mending fatty acid production. Another one of my favorite supplements is collagen which is rich in amino acids that quite literally, “seal the leaks” or perforations in your gut by repairing damaged cells and building new tissue. Other key nutrients include zinc, omega 3 fish oils, vitamin A, C, E as well as herbs such as slippery elm and aloe vera.

If you are one of the 45 million Americans with IBS, recognizing your triggers, identifying the root cause, and making the simple diet and lifestyle changes as outlined in my 4R Approach can go a long way towards returning you to optimal health.

Causes of IBS FAQs

What is IBS?

Irritable Bowel Syndrome (IBS) is a common functional gastrointestinal disorder (GI) classified by a group of symptoms such as abdominal pain or discomfort and changes in bowel patterns.

What causes IBS flare-ups?

Everybody has different IBS triggers, however the most common factors that may cause your IBS symptoms to flare are a poor diet, stress and anxiety, over-the-counter medication and lack of sleep.

Can stress cause IBS?

Yes! Stress is one of the largest triggers of IBS. That’s because when you feel stressed, your body releases stress hormones including cortisol, which affect both your digestive system and immune system. If you have IBS, your colon might be overly responsive to even the slightest disruption of your digestive system, triggering the diarrhea and stomach churning that those with IBS know all too well.

Which foods cause IBS?

Toxic and inflammatory foods such as gluten, dairy, grains and legumes, nightshades, sugar, caffeine, and alcohol have all shown to trigger symptoms of IBS.

Article Sources

  1. "Irritable. "D. "NCBI". "2007".
  2. Food Allergy in Irritable Bowel Syndrome: The Case of Non-Celiac Wheat Sensitivity. Pasquale Mansueto, Alberto D'Alcamo, Aurelio Seidita, Antonio Carroccio. NCBI. 2015.
  3. Irritable Bowel Syndrome. American College of Gastroenterology.
  4. Intestinal Barrier Function in Health and Gastrointestinal Disease. M Camilleri, K Madsen, R Spiller, B G Van Meerveld, G N Verne. Wiley Online Library. 2012.
  5. Eradication of Small Intestinal Bacterial Overgrowth Reduces Symptoms of Irritable Bowel Syndrome. M Pimentel, EJ Chow, H C Lin. NCBI. 2000.
  6. Relationship Between Irritable Bowel Syndrome, Worry, and Stress in Adolescent Girls. Sang-Wook Song, Seo-Jin Park, Se-Hong Kim, Sung-Goo Kang. NCBI. 2012.