Irritable bowel syndrome is a functional bowel disorder characterized by abdominal pain, changes in bowel habits, and altered stool consistency without any obvious organic cause. Among the four main subtypes defined by international criteria is the mixed type—IBS-M—where diarrhea and constipation repeatedly alternate.
What IBS-M is and how it differs from other types
According to the Rome criteria, IBS is divided as follows:
- IBS-C (constipation-predominant) – constipation predominates, with ≥25% of stools being hard or lumpy;
- IBS-D (diarrhea-predominant) – loose or watery stools predominate in ≥25% of cases;
- IBS-M (mixed type) – ≥25% of stools are hard or lumpy and at the same time ≥25% are loose or watery;
- IBS-U (unclassified) – other cases that cannot be clearly categorized.
Typical symptoms and manifestations of IBS-M
According to the Rome criteria and the Bristol Stool Scale, IBS-M is defined as a condition where:
- more than 25% of stools correspond to constipation (types 1–2),
- and at the same time more than 25% correspond to diarrhea (types 6–7).
This variability in stool consistency distinguishes IBS-M from purely constipation- or diarrhea-predominant types and is the main reason why patients often describe their symptoms as unpredictable and difficult to control.
IBS-M may involve:
- abdominal pain and cramps, often worsening after meals;
- bloating and gas;
- alternating hard (constipated) and loose (diarrheal) stools;
- a sense of urgency or incomplete evacuation;
- sometimes associated psychological issues (e.g., stress, anxiety) that can worsen symptoms.
Diagnostic approaches
IBS-M is diagnosed primarily based on symptoms and their duration, including stool consistency according to the Bristol Stool Scale.
However, since these symptoms may also indicate other conditions, additional diagnostic tests are recommended in some patients, especially if diarrhea predominates or symptoms change over time.
These may include:
- colonoscopy;
- stool testing to rule out infectious causes;
- fecal calprotectin testing to exclude inflammatory bowel diseases;
- breath tests (e.g., hydrogen test) to assess possible small intestinal bacterial overgrowth (SIBO).
What may help symptomatically
Management of IBS-M is usually individualized and combined, as there is no single universal approach that works for all patients.
Care may include:
- dietary modifications (e.g., reducing certain carbohydrates);
- lifestyle changes and regular physical activity;
- in selected cases, medications targeting predominant symptoms (diarrhea, constipation, or pain).
During diarrheal episodes, some patients also use adsorbents, which may help reduce loose stools, intestinal irritation, and bloating. However, they should be viewed only as symptomatic support, not as a treatment for IBS itself.
Diet and nutritional approaches
Diet plays an important role in IBS-M, as some foods may worsen symptoms while others may help regulate bowel movements.
In practice, the following are often considered:
- adjusting intake of fermentable carbohydrates (e.g., within a low-FODMAP approach), with respect to individual tolerance;
- increasing intake of soluble fiber, which can help normalize stool consistency—softening hard stools while also helping to form stools during diarrheal phases.
Psychological and behavioral factors
IBS-M is not only a disorder of bowel function. The interaction between stress, the nervous system, and the gut can significantly influence the intensity and fluctuation of symptoms. For some patients, incorporating psychological or behavioral approaches may therefore be beneficial as part of overall care.
Long-term alternation of diarrhea and constipation is physically and mentally exhausting and can significantly affect quality of daily life. That is why it is important not to underestimate these difficulties and to actively seek appropriate solutions. Early and individualized management can help reduce symptoms and significantly improve quality of life.