Irritable bowel syndrome (IBS) is a common condition affecting 7%–16% of the US population. IBS is a chronic, often disabling, functional bowel condition that can negatively impact quality of life and productivity at work, so it’s important that it is diagnosed and managed correctly¹.
IBS is associated with particular signs and symptoms, including:
Change in bowel habits
If any of these sound familiar, it might be worth considering a diagnosis of IBS.
Read on to learn more about the signs and symptoms of IBS, how it’s diagnosed, what other illnesses can be mistaken for IBS, and when you should see a doctor.
1. Abdominal pain
Abdominal pain is one of the most common symptoms of IBS. It is usually felt in the lower abdomen, but can also affect the whole abdomen. IBS pain is not typically located in the upper area of your stomach.
IBS pain can often be cramping in nature. One of the distinguishing features of IBS pain is that it usually tends to resolve or ease with a bowel movement. However, some patients report worsening of pain after going to the bathroom.
If your pain is constant and does not resolve or ease with a bowel movement or with passing gas, it could be a warning sign that the pain is caused by something other than IBS¹ ².
Diarrhea is common in IBS. If diarrhea is your predominant symptom, you may be diagnosed with ‘IBS with diarrhea’ (IBS-D). Approximately one-third of diagnosed IBS sufferers have IBS-D³.
The diarrhea in IBS is caused by a combination of mechanisms. Altered serotonin secretion in IBS regulates the motor function of the gut. This causes increased gut motility and transit time.
Diets high in FODMAP foods⁴ can lead to increased water being drawn into the small intestine as the fermentable fiber is broken down by bacteria. This causes the stool to become loose⁵. The increased gut transit time combined with loose, watery stools can lead to sudden, immediate urges to have bowel movements⁶. If you struggle with IBS-D, this can be a significant source of stress and anxiety.
IBS with constipation as the predominant symptom (IBS-C) is the most common form of IBS. Between 44% and 66% of people in one study were diagnosed with IBS-C – more than IBS-D and mixed IBS.
We have seen that serotonin can increase gut motility and transit time, but it can also decrease them. Slowed peristalsis and longer time in the gut lead to constipation and a hard stool.
Constipation in IBS is often accompanied by a feeling of incomplete evacuation after a bowel movement⁷.
4. Mixed constipation and diarrhea
Also called ‘alternating IBS,’ people who suffer from mixed IBS have bouts of diarrhea that alternate with periods of constipation. People with mixed IBS tend to have more severe symptoms than those with IBS-C or IBS-D⁸.
5. Mucus in stool
Whitish mucus may be present in or on your stool if you suffer from IBS⁹.
Green or red, bloody mucus is abnormal and not a symptom of IBS. You should see a doctor if you have mucus in your stool in any color other than white or cream.
6. Bloating and flatulence
Gas and bloating are among the most common symptoms of IBS. Bloating is often a feature of IBS-C.
Gas production is most likely the result of altered digestion and can be worsened by eating high FODMAP foods¹⁰. Many IBS sufferers with bloating and gas consider it to be the most frustrating and debilitating symptom¹¹.
7. Anxiety and depression
Anxiety and depression are closely linked to IBS.
People with underlying anxiety or depression are at higher risk of developing IBS, but the converse is also true. In more than 50% of IBS cases in one review, primary symptoms were in the gut and psychological symptoms developed later¹.
Fatigue is not often associated with IBS, but a review of 24 studies found that just over 50% of people suffering from IBS complained of fatigue. Increased fatigue was associated with females and younger age groups¹².
If you think you have IBS, it’s best not to self-diagnose. Make an appointment to see your doctor for a formal diagnosis.
IBS is diagnosed based on your symptoms. Your doctor will ask you:
What symptoms you have
How often you have symptoms
How long you’ve had symptoms
If you’ve had symptoms at least once a week for the past three months and your symptoms started more than six months before, you might be diagnosed with IBS².
Your doctor may also want to do some tests on you to exclude other, more serious conditions.
These tests could include:
Blood tests to look for inflammatory markers (to rule out inflammatory bowel disease), anemia (which can be linked to colon cancer), and markers to rule out coeliac disease
Stool sample to check for blood in your stool, fecal calprotectin or lactoferrin (which identifies bowel inflammation), and parasites or other infective agents (such as Giardia)
Your doctor may also do a physical exam that will include feeling your abdomen, listening to your abdomen with a stethoscope, and possibly a rectal exam.
If there are any signs or results that your doctor is not happy with, you may need to go for a colonoscopy to exclude conditions like cancer, inflammatory bowel disease, and diverticulitis.
Other gastrointestinal conditions can have similar symptoms to IBS.
Some of these are:
Inflammatory bowel disease – This commonly presents with abdominal pain and diarrhea, but there are other signs like blood in the stool and weight loss
Colorectal cancer – May cause any of the symptoms of IBS but also commonly causes blood in your stool, weight loss, and anemia
Coeliac disease – This can cause diarrhea and weight loss
Chronic gastroenteritis – Some parasites can cause ongoing diarrhea with or without abdominal cramping
There are some ‘red flags’ that are an indication of something more serious than IBS.
Make an appointment with your doctor as soon as possible if you:
Have developed symptoms over the age of 50
Have had a blood test that has picked up iron-deficiency anemia
Have weight loss associated with your symptoms
Have blood in your stools or have dark, tarry stools
Have persistent pain that isn’t relieved by passing gas or stools
IBS presents with a variety of symptoms, including abdominal pain, diarrhea, constipation, bloating, fatigue, depression, and anxiety.
The physical symptoms can be similar to those of other gastrointestinal disorders. Colorectal cancer, inflammatory bowel disease, coeliac disease, and chronic infection can be confused with IBS.
To diagnose IBS, your doctor will take a detailed history of your symptoms, ask about your family history and do a physical examination. If necessary, minor investigations like blood tests and a stool sample may be warranted.
Red flags that indicate you might be dealing with something more serious than IBS include blood in your stool, weight loss, anemia, and newly developed symptoms over 50 years of age.
Irritable bowel syndrome (2017)
Irritable bowel syndrome I Mayo Clinic
Symptoms and causes of irritable bowel syndrome I National Institute of Diabetes and Digestive and Kidney Disorders (NIDDK)
Bloating is associated with worse quality of life, treatment satisfaction, and treatment responsiveness among patients with constipation-predominant irritable bowel syndrome and functional constipation (2016)
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