IBS-M: The Cycle and The Solution

Written by: Jessica Roocroft, RD

Updated: March 31st, 2025

Welcome to the world of IBS-M, which stands for Irritable Bowel Syndrome with mixed bowel habits. This condition means you switch between constipation and diarrhea. Let’s get into it!

What is IBS-M, and How Prevalent is It?

IBS-M is linked to the miscommunication between your brain and gut. It’s like a bad game of telephone where the messages get mixed up.

This can lead to:

Altered sensitivity of your gut’s nerves
- Usually an increase in pain with even normal amounts of gas and poop in your gut.
Changes in your microbiota
- Meaning the types and amounts of “gut bugs” residing in your intestines have changed- and not for the better
Speeding up or slowing down of the movement of food along your digestive tract
- Leading to diarrhea, constipation, or both in the case of IBS-M

Fact: About one-third of all IBS cases are IBS-M. So if this is you, please know that you are certainly not alone.

How is IBS-M Diagnosed?

Before diagnosing IBS-M, doctors must rule out other conditions based on your health history, and any red flags (like low iron, bloody diarrhea, and if you’ve lost weight when you weren’t trying to) among others.

In Canada, Celiac Disease is underdiagnosed- and it’s important to be counted among conditions that are ruled out first, before an IBS diagnosis is made. So avoid deleting gluten from your diet before getting screened (a blood test called a IgA-tTg)- otherwise the test may not be reliable.

If your tests are negative, usually the Rome IV criteria to diagnose IBS is next, which is recurrent belly pain at least one day a week in the last 3 months (and it’s been happening for at least 6 months) plus at least two of the below:

Pain related to pooping
Changes in how often you have bowel movements
- This is called stool “frequency”
Changes in the form of your stool, like being too hard or too watery
This is called stool “consistency”

Then, what should happen for the best care possible (but may be missed) is assigning you an IBS Subtype:

You meet the criteria for IBS-M as your IBS subtype if the above is met, plus:

More than 25% of your abnormal poops are loose or watery (Type 6 or 7)

AND

More than 25% of your abnormal poops are hard, dry and/or lumpy (Type 1 or 2)

Before we begin on what can be done about IBS-M, and after diagnosis by a medical doctor, working with a Registered Dietitian who focuses on IBS is researched to be a key step to manage IBS, with as few issues as possible, like:

Impacting your relationship with food
Experiencing nutrient deficiencies, like calcium, zinc, magnesium, fibre, and more)
Navigating eating out and social situations involving food

just to name a few.

Dietary “Tweaks” for IBS-M

Diet can help manage IBS- But it is not the end all be all.

The Low FODMAP Diet is a common strategy which reduces certain carbohydrates that can cause symptoms when they are fermented in the gut.

Grab one of Jessica Roocroft’s free IBS Mini Guides linked here, including low FODMAP swaps, shopping list, and sample meal plan if you’d like to get a science-backed head start.

There’s one for each type of IBS- including IBS-M.

Back to the job at hand…FODMAPs!

The FODMAP subgroups with a few food examples, are:

Fructans
- Like in garlic, shallot, onion, regular bread, and certain nuts like cashews and pistachios
GOSs
- Beans, peas, legumes/pulses, and also certain nuts like cashews and pistachios
Lactose
- Found in “wet” dairy (milk, yogurt, cottage cheese, etc, unless the product is labeled “lactose-free”)
Fructose
- Apples, pears, mangoes, honey
Sorbitol
- Blackberries, stone fruits, like apricots, prunes & prune juice
- Sometimes added sweetening agent in “low” or “no sugar added sweets”
- Apples and pears are also included in this category
Mannitol
- Mushrooms, cauliflower, celery
- Sometimes added sweetening agent in “low” or “no sugar added sweets”

There are also high FODMAP additives: Maltiol, lactitol, xylitol, erythritol, inulin/chicory root fibre, high fructose corn syrup, and more that can sneak into packaged foods.

PS: What’s listed above is essentially the “Gentle Low FODMAP Diet” list of foods.

This is a less restrictive form of Low FODMAP Diet compared to a “Full” Low FODMAP Diet, where portion sizes are prescribed, and even more foods are eliminated.

Pro-tip: By swapping these out (with the guidance of a Dietitian, and perhaps an appropriate science-based low FODMAP app), studies show that even the less restrictive “Gentle Low FODMAP Diet” can lead to comparable symptom relief from gas, bloating, abdominal pain as the “full” low FODMAP Diet.

Jessica Roocroft’s go-to apps for Low FODMAP content of foods are:

Monash App

Great for looking up whole food sources of FODMAPs.

FODMAP Friendly App

They have a new feature where you can input foods and assess for “FODMAP stacking”

Spoonful App

This one is great for scanning foods in a package with a barcode when you just need the red, yellow, or green light as to whether its likely low FODMAP (or not)

Examples of foods that are Low FODMAP

Grains:
- Sourdough bread
- Low FODMAP pasta (usually in the form of a gluten free pasta made from rice, quinoa, and corn flour)
- Rice
- Quinoa
- Potato
- Rolled oats in ½ cup or less
Fruits:
- Blueberries
- Kiwis
- Oranges
- Bananas (without brown spots)
Vegetables:
- Carrots
- Lettuce
- Eggplant
- Canned corn
Dairy & Alternatives:
- Lactose-free dairy
- Almond milk
- Rice milk
- Soy milk (if made from soy protein isolate, specifically)
- Cheese (all “dry” forms of dairy like solid or aged cheeses are typically less than 1 gram of lactose, and thus are low FODMAP.)
  - There is no need to buy “lactose-free” labelled products as these are already very low lactose
Tip: If you want to double check if your cheese is lactose free, look at the grams of “sugar” listed on the Nutrition Facts Table. It’ll usually say “0 grams”. As lactose is a type of sugar, this would mean the product is lactose-free!

Proteins
- Lower FODMAP beans & legumes like butter beans, cannellini beans, canned, strained & rinsed lentils
- Lower FODMAP nuts, like pecans, peanuts, walnuts, and macadamia nuts
- Fresh, non-marinated, lean cuts of proteins
- Extra firm tofu, pressed
Oils & fats:
- All are low FODMAP in their natural form (without anything added to them) as FODMAPs are a group of fermentable carbohydrates

Supplement Tips for IBS-M

Supplements can help, but always check with your doctor first.

Here are some options::

Soluble fibre like acacia senegal, or partially hydrolyzed guar gum:
- On diarrhea days, a soluble fibre supplement can work wonders to form loose bowel movements due to their ability to hold onto water
Magnesium citrate or another “water magnet” like PEG taken at nighttime to prevent constipation days in the first place
- This is key for getting rid of the IBS-M roller coaster constipation to diarrhea cycling as IBS-M is rooted in constipation
  - Note: Magnesium citrate is not right for everyone- speak to your Dr. especially if you have kidney or neuromuscular issues
FODMAP-digesting enzymes can increase food freedom
- Enzyme blends that contain fructan hydrolase, lactase and alpha-galactosidase taken with meals containing certain high FODMAP foods can help increase food freedom
Enteric-coated peppermint oil capsules
- May ease abdominal pain and sensations like bloating when taken 60 minutes before a meal

Medications for IBS-M

Unfortunately, there aren’t any medications made specifically for IBS-M.

Some doctors may suggest Tricyclic Antidepressants (TCAs), but while they can be life-changing for some in terms of reducing abdominal pain, they can cause constipation and many other well documented side effects.

It’s important to note that these side effects can be dose dependent, and only a low dose of a TCA may be prescribed for some cases.

Talk to your doctor about side effects, other options, and/or perhaps discussing using as small of a dose as possible for the maximum benefit.

Addressing the Gut-Brain Interaction

As IBS is now classified as a disorder of the gut-brain interaction (a “DGBI”) there are effective treatment options to target this.

Gut Directed Hypnotherapy (GDH) addresses the faulty signals of the gut-brain axis causing the gut to move too slow (or too fast), or overly sense the normal sensations of digestion and elimination as painful.

There are apps that can help with this, and the effects can last long term.

Fun fact: Gut Directed Hypnotherapy is “subtype agnostic”. This is a fancy way to say that it doesn’t care which subtype you are- it’s likely equally effective across all IBS subtypes.

Translation: It can address IBS symptoms whether you are an IBS-D, C, M, or U.

What IBS-M is Not:

IBS-M can look like other conditions but isn’t the same. It’s not:

Celiac Disease
- Ensure you’re properly screened, and do not remove gluten from your diet beforehand
Overflow diarrhea
- When liquid stool sneaks past harder, stuck poop
Diarrhea before one’s menstrual cycle
- This is due to hormone fluctuations, not necessarily IBS-M
Constipation, then diarrhea due to a day of high sugar, or sugar alcohols
Constipation with a “layer” of histamine intolerance
SIBO (Small Intestinal Bacterial Overgrowth) or IMO (Intestinal Methanogen Overgrowth)
- Essentially certain gut bugs are overgrowing, and possibly growing too far up the gut (when they should be sticking to residing in the large intestine for the most part
- This is a common additional “layer” to someone with IBS affecting up to 25% of those with IBS-M specifically.
- It usually requires a breath test to measure hydrogen and methane levels, and if either are positive, certain (potentially expensive) antibiotic therapies can be prescribed by your Dr.
  - While it’s possible to have both IBS-M and SIBO/IMO, treating the IBS-M first using a “multimodal” approach (like combining the options in this article), has the most evidence that it will lead to good symptom management as opposed to assuming SIBO first (as SIBO/IMO is only involved 25% of the time according to research)

Final Thoughts

Here are some key points to remember:

IBS-M diagnosis involves ruling out other conditions and using the Rome IV criteria
- Knowing your IBS Subtype is KEY for accessing relevant info and care
IBS-M involves regular cycles of alternating between painful constipation and diarrhea, often with bloating, gas, urgency, and other symptoms
IBS in general is linked to the gut-brain axis’s miscommunication
The Low FODMAP Diet, certain supplements, and gut directed hypnotherapy can help manage the majority of someone’s symptoms
Always work with healthcare professionals, like a specially trained Registered Dietitian, to tailor treatments

IBS-M can be a tough ride, but with the right care and support, it’s possible to live well with the condition.

So never stop advocating for yourself and getting help from the right professionals!

References:

Amitriptyline at Low-Dose and Titrated for Irritable Bowel Syndrome as Second-Line Treatment in primary care (ATLANTIS): a randomised, double-blind, placebo-controlled, phase 3 trial
Ford, Alexander CFord, Alexander C. et al.
The Lancet, Volume 402, Issue 10414, 1773 – 1785
Peters SL, Gibson PR, Halmos EP. Smartphone app-delivered gut-directed hypnotherapy improves symptoms of self-reported irritable bowel syndrome: A retrospective evaluation. Neurogastroenterol Motil. 2023 Apr;35(4):e14533. doi: 10.1111/nmo.14533. Epub 2023 Jan 20. PMID: 36661117.
Lacy BE, Cangemi D, Vazquez-Roque M. Management of Chronic Abdominal Distension and Bloating. Clin Gastroenterol Hepatol. 2021 Feb;19(2):219-231.e1. doi: 10.1016/j.cgh.2020.03.056. Epub 2020 Apr 1. PMID: 32246999.
Villanueva-Millan MJ, Leite G, Wang J, Morales W, Parodi G, Pimentel ML, Barlow GM, Mathur R, Rezaie A, Sanchez M, Ayyad S, Cohrs D, Chang C, Rashid M, Hosseini A, Fiorentino A, Weitsman S, Chuang B, Chang B, Pichetshote N, Pimentel M. Methanogens and Hydrogen Sulfide Producing Bacteria Guide Distinct Gut Microbe Profiles and Irritable Bowel Syndrome Subtypes. Am J Gastroenterol. 2022 Dec 1;117(12):2055-2066. doi: 10.14309/ajg.0000000000001997. Epub 2022 Sep 6. PMID: 36114762; PMCID: PMC9722381.
Shah A, Ghoshal UC, Holtmann GJ. Unravelling the controversy with small intestinal bacterial overgrowth. Curr Opin Gastroenterol. 2023 May 1;39(3):211-218. doi: 10.1097/MOG.0000000000000928. Epub 2023 Mar 1. PMID: 37144539.
Onana Ndong, P., Boutallaka, H., Marine-Barjoan, E., Ouizeman, D., Mroue, R., Anty, R., Vanbiervliet, G. and Piche, T. (2023), Prevalence of small intestinal bacterial overgrowth in irritable bowel syndrome (IBS): Correlating H2 or CH4 production with severity of IBS. JGH Open, 7: 311-320. https://doi.org/10.1002/jgh3.12899
Lacy BE, Pimentel M, Brenner DM, Chey WD, Keefer LA, Long MD, Moshiree B. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2021 Jan 1;116(1):17-44. doi: 10.14309/ajg.0000000000001036. PMID: 33315591.