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Alyssa Simpson RD, CDE, CLT
Alyssa Simpson

(602) 422-9800

Sibo Doctor Approved
certified gastrointestinal nutritionist
Sibo Doctor Approved
certified gastrointestinal nutritionist

Symptoms of SIBO vs IBS: How to Figure Out Which One You Have

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difference between IBS and SIBO

Table of Contents

If you’re here, you probably have digestive issues. And I just want to take a moment and acknowledge how hard it can be to research and talk about those issues. We all know that digestion and elimination (yes ?) are normal biological functions. But when things are going wrong, it carries an element of embarrassment — or maybe even shame.

I just want to say that I’m glad you’re here. I’m proud of the safe space I’ve created where you can find the help you need, whether that means reading an article to get some ideas of what to try or working with me 1:1 for a personalized approach to solving your issues.

Digestive problems are no fun. But I’m glad you took the leap of researching, and of choosing not to believe the doctor who told you to “just live with it”. There are answers for you. So let’s dig in…

Are you dealing with some or all of these symptoms on a consistent basis?

✔ Stomach pain and/or cramping

✔ Constipation

✔ Diarrhea

✔ Bloating

✔ Gas

✔ Nausea

✔ Loss of appetite

If so, you may have Irritable Bowel Syndrome, or IBS for short. Now what about this next list of symptoms? Do you struggle with some or all of these?

✔ Stomach pain and/or cramping

✔ Constipation

✔ Diarrhea

✔ Bloating

✔ Gas

✔ Nausea

✔ Loss of appetite

Then you may have SIBO, or small intestinal bacterial overgrowth.

Yes, those are the same symptoms. And because the symptoms are so similar, it can be difficult to figure out which condition is causing you problems. Or, it could even be both.

Symptoms of SIBO vs. IBS

IBS and SIBO are two very different, but often related conditions that share many common symptoms. Yes, they are both digestive disorders. And they can both be related to changes in the gut microbiome — the bacteria that live in your large intestine.

Either condition can cause symptoms that range from mild to life-alteringly severe. They even both benefit from some of the same dietary approaches. But they aren’t the same thing.

Here’s a quick rundown on the differences between IBS and SIBO:

IBS affects the large intestine — the ‘B’ in IBS stands for ‘bowel’

SIBO happens in the small intestine

SIBO can result in nutrient deficiencies, while IBS generally doesn’t

SIBO can result in unexplained weight loss, while IBS doesn’t

SIBO is easier to diagnose — more on that in a minute.

If you’re experiencing the digestive symptoms that are common to both IBS and SIBO, asking Dr. Google or trying to diagnose yourself just isn’t going to cut it. These aren’t condition-specific illnesses that can be easily differentiated without some testing from a knowledgeable practitioner.

How can I figure out if I have SIBO or IBS?

IBS Diagnosis

IBS diagnosis is a little more complicated, so we’ll start there. An IBS diagnosis is based primarily on an assessment of your symptoms as you report them to your practitioner. So make sure you’re being totally honest — no minimizing what you’re going through!

Once you’ve reported your symptoms, your practitioner may want to run some of the following tests to rule out other conditions:

? Blood test to rule out celiac disease

? Stool test to check for intestinal parasites

? X-ray of your intestines to check for potential blockages

? Colonoscopy to check for colon cancer

? CT Scan to look for pancreas or gallbladder issues

? Lactose intolerance test to see if you produce lactase — the enzyme needed to digest the sugar in dairy products.

Once they’ve taken all of that information into account, your practitioner may give you an IBS diagnosis. IBS can be somewhat of a catch-all for unexplained digestive symptoms. But that doesn’t make it any less valid than any illness or health concern. IBS is a real thing that affects up to 15% of the population of American adults.

SIBO Diagnosis

SIBO is easier to diagnose. There are a couple of tests that can determine whether or not you have an overgrowth of bacteria in your small intestine — better known as SIBO.

The easiest test for SIBO is the breath test. This works because the bacteria in your small intestine release hydrogen and methane when they ferment the food that passes through your digestive system. These gasses can be identified in a non-invasive breath test that can be performed at home.

It involves an overnight fast, drinking a sweet drink, and 2-3 hours. But it’s a pain-free and relatively simple process.

SIBO can also be diagnosed by using a more definitive (and invasive) test where your doctor will take a tissue sample from the small intestine during an endoscopy. The tissue can then be examined for the presence of a bacterial overgrowth.

Could I have both SIBO and IBS?

The short answer is yes. In fact, SIBO and IBS are like peanut butter and jelly. You can have them separately, but they seem to be together most of the time. Studies show that up to 80% of IBS patients also have SIBO. So I routinely screen the vast majority of my IBS patients for this bacterial overgrowth.

Research has yet to uncover the precise nature of the relationship between IBS and SIBO. It’s possible that one causes the other. Some theories propose that the bacterial overgrowth in the small intestine disrupts how the digestive tract that pushes food along, leading to IBS symptoms. The uninvited bacteria living in the small intestine may also trigger an immune reaction, leading to the inflammation that is so common in IBS.

Or maybe the gut imbalance that can occur with IBS causes bad bacteria to migrate up into the small intestine, causing SIBO. We honestly don’t know for sure how the two conditions are related. But it’s clear that they often are.

Are SIBO and IBS treatable?

Yes. In fact, there are things you can do that may help with both. Many of the dietary changes I recommend for my IBS patients also help with SIBO. And with SIBO, there are medicinal interventions and supplements that can help slow down the growth.

But as always, the key in treating your stomach issues is getting to the root cause. Otherwise, you’re just trying to control the symptoms. Any time you experience symptoms — digestive or otherwise — your body is sending you a message that something is wrong or out of balance. And the only way to get rid of the symptoms (and keep them from coming back) is to treat the underlying cause or imbalance.

You can take medications, add supplements, and even overhaul your diet. In fact, I use a lot of these therapeutic approaches in my practice. But unless you figure out what’s really going on, your symptoms are likely to come back as soon as you stop these interventions.

When I work with clients, I always address their real issues so they can reduce or even eliminate the interventions that are keeping their symptoms at bay. If you’re ready to get to the bottom of what’s really going on with you, I’m here to help. You can book a consultation with me here.

If you need some help in the meantime, I’ve created a free resource just for you! Whether you have IBS, SIBO, IBS and SIBO, or general undiagnosed stomach issues, the resources in my IBS Resource Guide can help you on your journey toward feeling better. Whether you need to know the best apps for your low FODMAP diet or you need some emergency relief, I’ve got you covered.

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