IBS-D vs IBS-C vs IBS-M: Understanding the Different Subtypes of IBS
Irritable bowel syndrome (IBS) affects between 7% to 21% of people. It’s often thought of as a standalone condition, defined by diarrhoea, constipation, or abdominal discomfort. However, IBS can present in three different ways.
The three main IBS subtypes include:
IBS-D (diarrhoea predominant IBS)
IBS-C (constipation predominant IBS)
IBS-M (mixed IBS)
Understanding which type of IBS you have can make managing symptoms much easier. Each subtype tends to have its own symptom patterns, triggers, and treatment approaches, helping people identify what may be worsening their condition.
What Are the IBS Subtypes?
IBS is a functional gut disorder characterised by disruption in how your brain and gut work together. Most commonly, it’s a chronic disorder, with people regularly dealing with abdominal pain, cramps, bloating, gas, and abnormal bowel movements.
IBS can present in different ways depending on a person’s dominant bowel habits and symptom patterns. Knowing your specific subtype can help your doctor advise on the best treatment plan.
Doctors usually classify IBS subtypes using the Bristol Stool Chart, a medical tool that categorises stool consistency from hard and lumpy to entirely liquid. This helps healthcare professionals determine whether diarrhoea, constipation, or a mixture of both is the dominant symptom pattern over time.
IBS-D: Diarrhoea Predominant IBS
IBS-D is diagnosed when more than a quarter of stools on abnormal bowel movement days are loose. Less than a quarter will be hard and lumpy.
People with IBS-D commonly experience abdominal pain alongside loose stools and urgency. Other common symptoms include bloating or diarrhoea associated with the frequency or consistency of their stool. Symptoms are often worse after eating.
People with IBS-D can be triggered by stress and anxiety, fatty or spicy foods, caffeine, alcohol, or gut infections. Treatment often revolves around dietary changes, stress management, and soluble fibre to help bulk up the stools.
IBS-C: Constipation Predominant IBS
IBS-C is the opposite of IBS-D. It’s defined by hard, lumpy stools for more than a quarter of days where bowel movements are abnormal, meaning less than a quarter will be loose.
Aside from hard, infrequent stools, common symptoms of IBS-C include straining, bloating or discomfort, and the feeling of being unable to fully empty bowels.
Common triggers include low fibre intake, dehydration, stress, and a sedentary lifestyle. If you have IBS-C, your doctor may encourage you to drink more water, gradually increase fibre intake, and be more physically active. Osmotic laxatives and other medical support can be temporarily provided, if needed.
IBS-M: Mixed IBS
IBS-M (or IBS-A) is a combination of IBS-D and IBS-C. In these cases, patients will have both diarrhoea and constipation for at least 25% of days with abnormal bowel movements.
The unpredictable nature of symptoms can make it difficult to manage, especially as people can have the triggers of both conditions. A core part of treatment is symptom tracking. Your doctor will help you find strategies that work for you.
Can Your IBS Subtype Change Over Time?
Your IBS subtype isn’t necessarily static. Even if you identify the exact subtype, it can change over time due to stress, infection, hormonal changes, diet, and medication use.
It’s nothing to panic about.
Simply inform your doctor of the change, and they’ll advise you how to adjust your diet and lifestyle accordingly. Fluctuations are common and are a normal part of IBS.
When to Seek Medical Advice
Although IBS is common, not all digestive symptoms should automatically be assumed to be IBS. It’s important to speak to a healthcare professional if you experience red-flag symptoms such as:
Unexplained weight loss
Blood in your stool
Anaemia
Persistent symptoms during the night
Many digestive conditions can overlap with IBS, including inflammatory bowel disease (IBD), coeliac disease, and bowel cancer. Getting a proper diagnosis can help rule out more serious causes and ensure you receive the most appropriate treatment and support.
Getting Tested for Irritable Bowel Syndrome
IBS doesn’t always present alone. Nor can any single test definitively diagnose it. However, certain blood tests, stool tests, and breath tests can eliminate other potential causes that may contribute to IBS or provide another explanation for your symptoms.
The Functional Gut Clinic provides diagnostic testing for people dealing with irritable bowel syndrome to help rule out the other potential causes for your symptoms. All tests are fully accredited and regulated by the Care Quality Commission.
If you want to learn more about testing, you can see our range of gut tests. Or read more about IBS and other potential causes.
Check out the next article: Low FODMAP Diet for IBS: A Beginner's Guide to Elimination, Reintroduction and Personalisation
