What Is IBS-M?

Medically Reviewed by Zilpah Sheikh, MD on January 28, 2026

Anybody can get diarrhea sometimes. The same goes for constipation. But if you get both of them often, you may have a type of irritable bowel syndrome (IBS). Specifically, you may have IBS-M, the mixed type.

IBS causes digestive problems such as cramping, belly pain, and bloating, as well as diarrhea, constipation, or both. There are three types, which are grouped by the main bowel problem involved:

IBS-D (diarrhea)
IBS-C (constipation)
IBS-M (mixed), also known as IBS-A (alternating)

It's called "mixed" because you go back and forth between diarrhea and constipation, sometimes pretty quickly. And some studies have found that people with this type tend to have more belly pain or discomfort than those who have IBS-C or IBS-D.

The difference between occasional digestive issues and IBS is that, with IBS, discomfort and bowel troubles are common and go on for months.

What Causes IBS-M?

Doctors don't really know what causes the condition. It may happen for several reasons, which could differ from person to person. Some possible reasons behind it include:

Your genes
Infections
Inflammation
The way your brain and your digestive tract signal each other
Psychological factors, such as stress or past trauma
Your diet
Gut bacteria

How Is IBS-M Diagnosed?

There are no tests that can tell for sure whether you have IBS-M. It's tough for doctors to diagnose which type you may have. They generally rely on the symptoms you describe and their experience treating IBS to make a diagnosis.

Your doctor may ask about your diet, symptoms, lifestyle, whether others in your family have digestive problems, and medications you take.

Your doctor may order a few common tests, such as:

Basic blood tests, including a complete blood count, to rule out other diseases
A blood test for celiac disease (when your body can't digest gluten)
Stool test (if your main symptom is diarrhea)

If you have any "red flag" issues, such as weight loss, fever, bleeding, or a family history of digestive diseases (including colon cancer), you may need a colonoscopy. For this test, the doctor looks inside your large intestine using a tool with a tiny camera.

Treatment for IBS-M

There is no cure for IBS, so the goal of treatment is to ease your symptoms to help you feel better and manage your daily activities. When constipation is a major problem, as it often is with IBS-M, your doctor may suggest you take a fiber supplement.

Prescription medications may also be part of your treatment. They may include drugs for constipation, diarrhea, pain, depression, or anxiety. However, drug treatment is often a challenge with IBS-M. That's because medication for diarrhea can make constipation worse, and vice versa. The best medications for IBS-M may be those that have only a short-term effect.

How to Live Well With IBS-M

For some, medications can be an important part of getting IBS-M under control. But there's more you can do to feel better — physically and mentally — with this condition.

You may need to try some diet changes. This may help you find out which foods make you feel better and which ones worsen your symptoms. For example, if gas is a problem, see if you feel better by avoiding foods that can cause it, such as:

Beans
Onions
Celery
Carrots
Raisins
Apricots
Prunes
Brussels sprouts
Pretzels
Bagels

Many people with IBS feel better when they follow a diet that's low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) — a type of carbohydrate. Others say it helps to avoid foods that have lactose, the sugar in milk.

If you have any new symptoms, tell your doctor. Worrying about them isn't going to help your body or mind. If something changes, go straight to your doctor to find out what it may mean.

Relaxation techniques can also be a big help for people with the condition. Techniques such as meditation or hypnosis can help ease symptoms and calm some of the stress of living with IBS-M.

Takeaways

A mixed type of irritable bowel syndrome called IBS-M involves alternate bouts of diarrhea and constipation, sometimes happening quickly. The discomfort and bowel troubles it causes can go on for months. Treatment may include medicines for constipation, diarrhea, pain, and depression or anxiety. Trying a diet that's low in specific carbs called FODMAPS, or avoiding foods that have lactose, may help you feel better, too. So might easing stress with techniques such as meditation.

IBS-M FAQs

Is IBS-M a disability?

In general, irritable bowel syndrome is a long-term condition that may lead to disability for some people. Without a good treatment plan, IBS may sometimes keep you from doing important daily tasks. For instance, folks with IBS may miss three times as many work days as those without bowel symptoms, research suggests.