Irritable bowel syndrome (IBS) affects between 6–18% of people worldwide.
This condition involves changes in frequency or form of bowel movements and lower abdominal pain (1).
Diet, stress, poor sleep and changes in gut bacteria may all trigger symptoms.
However, triggers are different for each person, making it difficult to name specific foods or stressors that everyone with the disorder should avoid (2).
This article will discuss the most common symptoms of IBS and what to do if you suspect you have it.
Abdominal pain is the most common symptom and a key factor in diagnosis.
Normally, your gut and brain work together to control digestion. This happens via hormones, nerves and signals released by the good bacteria that live in your gut.
In IBS, these cooperative signals become distorted, leading to uncoordinated and painful tension in the muscles of the digestive tract (3).
This pain usually occurs in the lower abdomen or the entire abdomen but is less likely to be in the upper abdomen alone. Pain typically decreases following a bowel movement (4).
Other treatments include bowel relaxants like peppermint oil, cognitive behavior therapy and hypnotherapy (6).
For pain that doesn’t respond to these changes, a gastroenterologist can help you find a medication specifically proven to ease IBS pain.
Summary: The most common symptom of IBS is lower abdominal pain that is less severe after a bowel movement. Dietary modifications, stress-reducing therapies and certain medications can help reduce pain.
Diarrhea-predominant IBS is one of the three main types of the disorder. It affects roughly one-third of patients with IBS (7).
A study of 200 adults found that those with diarrhea-predominant IBS had, on average, 12 bowel movements weekly — more than twice the amount of adults without IBS (8).
Accelerated bowel transit in IBS can also result in a sudden, immediate urge to have a bowel movement. Some patients describe this as a significant source of stress, even avoiding some social situations for fear of a sudden onset of diarrhea (9).
Additionally, stool in the diarrhea-predominant type tends to be loose and watery and may contain mucus (10).
Summary: Frequent, loose stools are common in IBS, and are a symptom of the diarrhea-predominant type. Stools may also contain mucus.
Although it seems counterintuitive, IBS can cause constipation as well as diarrhea.
Constipation-predominant IBS is the most common type, affecting nearly 50% of people with IBS (11).
Altered communication between the brain and bowel may speed up or slow down the normal transit time of stool. When transit time slows, the bowel absorbs more water from stool, and it becomes more difficult to pass (10).
Constipation is defined as having fewer than three bowel movements per week (12).
“Functional” constipation describes chronic constipation not explained by another disease. It is not related to IBS and is very common. Functional constipation differs from IBS in that it is generally not painful.
In contrast, constipation in IBS includes abdominal pain that eases with bowel movements.
Constipation in IBS also often causes a sensation of an incomplete bowel movement. This leads to unnecessary straining (13).
Along with the usual treatments for IBS, exercise, drinking more water, eating soluble fiber, taking probiotics and the limited use of laxatives may help.
Summary: Constipation is very common. However, abdominal pain that improves after a bowel movement and a sensation of incomplete bowel movements after passing stool are signs of IBS.
Mixed or alternating constipation and diarrhea affects about 20% of patients with IBS (11).
Diarrhea and constipation in IBS involve chronic, recurring abdominal pain. Pain is the most important clue that changes in bowel movements are not related to diet or common, mild infections (4).
This type of IBS tends to be more severe than the others with more frequent and intense symptoms (14).
The symptoms of mixed IBS also vary more from one person to another. Therefore, this condition requires an individualized treatment approach rather than “one-size-fits-all” recommendations (15).
Summary: About 20% of patients with IBS experience alternating periods of diarrhea and constipation. Throughout each phase, they continue to experience pain relieved by bowel movements.
Slow-moving stool in the intestine often becomes dehydrated as the intestine absorbs water. In turn, this creates hard stool, which can exacerbate symptoms of constipation (16).
Prompt movement of stool through the intestine leaves little time for absorption of water and results in the loose stools characteristic of diarrhea (10).
IBS can also cause mucus to accumulate in stool, which is not usually associated with other causes of constipation (17).
Blood in stool may be a sign of another, potentially serious medical condition and deserves a visit to your doctor. Blood in stool may appear red but often appears very dark or black with a tarry consistency (12).
Summary: IBS changes the time stool remains in your intestines. This changes the amount of water in stool, giving it a range from loose and watery to hard and dry.
Altered digestion in IBS leads to more gas production in the gut. This can cause bloating, which is uncomfortable (18).
Many with IBS identify bloating as one of the most persistent and nagging symptoms of the disorder (19).
Summary: Gas and bloating are some of the most common and frustrating symptoms of IBS. Following a low-FODMAPs diet can help reduce bloating.
Up to 70% of individuals with IBS report that particular foods trigger symptoms (23).
Two-thirds of people with IBS actively avoid certain foods. Sometimes these individuals exclude multiple foods from the diet.
Why these foods trigger symptoms is unclear. These food intolerances are not allergies, and trigger foods don’t cause measurable differences in digestion.
Summary: Many people with IBS report specific trigger foods. Some common triggers include FODMAPs and stimulants, such as caffeine.
Over half of people with IBS report fatigue (27).
In one study, 160 adults diagnosed with IBS described low stamina that limited physical exertion in work, leisure and social interactions (28).
Another study of 85 adults found that the intensity of their symptoms predicted the severity of fatigue (29).
IBS is also related to insomnia, which includes difficulty falling asleep, waking frequently and feeling unrested in the morning (30).
Another study of 50 men and women found that those with IBS slept about an hour longer yet felt less refreshed in the morning than those without IBS (32).
Interestingly, poor sleep predicts more severe gastrointestinal symptoms the following day (33).
Summary: Those with IBS are more fatigued and report less refreshing sleep compared to those without it. Fatigue and poor sleep quality are also related to more severe gastrointestinal symptoms.
IBS is linked to anxiety and depression, as well.
It’s unclear whether IBS symptoms are an expression of mental stress or whether the stress of living with IBS makes people more prone to psychological difficulties.
Whichever comes first, anxiety and digestive IBS symptoms reinforce one another in a vicious cycle.
In a large study of 94,000 men and women, people with IBS were over 50% more likely to have an anxiety disorder and over 70% more likely to have a mood disorder, such as depression (34).
Another study compared levels of the stress hormone cortisol in patients with and without IBS. Given a public speaking task, those with IBS experienced greater changes in cortisol, suggesting greater stress levels (35).
Summary: IBS can produce a vicious cycle of digestive symptoms that increase anxiety and anxiety that increases digestive symptoms. Tackling anxiety can help reduce other symptoms.
If you have symptoms of IBS that interfere with your quality of life, visit your doctor, who can help diagnose IBS and rule out other diseases that mimic it.
IBS is diagnosed by recurrent abdominal pain for at least 6 months, combined with weekly pain for 3 months as well as some combination of pain relieved by bowel movements and changes in frequency or form of bowel movements.
Your doctor may refer you to a gastroenterologist, a specialist in digestive diseases, who can help you identify triggers and discuss ways to control your symptoms.
Lifestyle changes, such as a low-FODMAPs diet, stress relief, exercise, drinking plenty of water and over-the-counter laxatives can also help. Interestingly, a low-FODMAPs diet is one of the most promising lifestyle changes for alleviating symptoms (37).
Additionally, avoiding digestive stimulants, such as caffeine, alcohol and sugary beverages, can reduce symptoms in some people (41).
If your symptoms don’t respond to lifestyle changes or over-the-counter treatments, there are several medications proven to help in difficult cases.
If you think you have IBS, consider keeping a journal of foods and symptoms. Then, take this information to your doctor to help diagnose and control the condition.