What Is IBS-M?

Medically Reviewed by Arefa Cassoobhoy, MD, MPH on September 17, 2023
3 min read

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 like cramping, belly pain, and bloating; and diarrhea, constipation, or both. There are three types, which are grouped by the main bowel problem that you have.

  • 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 D.

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

Doctors don’t really know what causes the condition. It may happen for a number of reasons, which could be different 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, like stress or past trauma
  • Your diet
  • Gut bacteria

There are no tests that can tell for sure whether you have IBS-M. It’s tough for doctors to diagnose any type of the condition. 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, if 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)
  • If your main symptom is diarrhea, your doctor may test your stool 

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.

There is no cure for IBS, so the goal of treatment is to ease your symptoms so you feel better and can tackle 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, and 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.

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 to find out which foods make you feel better and which ones make your symptoms worse. 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 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 like meditation or hypnosis can help ease symptoms and calm some of the stress of living with IBS-M.