IBS (irritable bowel syndrome) is a condition that affects the digestive system causing symptoms such as abdominal pain, bowel habit changes, excess gas, bloating (abdominal distention), abdominal cramping, and food intolerances.
IBS is considered a “functional” disorder because it is a problem with the movement (motility) of the digestive tract rather than a result of damage to the tissues of the digestive system.
There are three different types of IBS:
- IBS with diarrhea (IBS-D)
- IBS with constipation (IBS-C)
- IBS with mixed bowel habits (IBS-M)
IBS is not the same as Crohn’s disease or colitis, which are separate conditions referred to as inflammatory bowel disease (IBD).
Symptoms of irritable bowel syndrome (IBS) include:
- Abdominal pain, often related to bowel movements
- Changes in bowel movements, which may be diarrhea, constipation, or both, depending on the type of IBS
- Bloating
- Feeling as if a bowel movement is incomplete
- Whitish mucus in the stool
Women with IBS may have increased symptoms during their periods.
People who have IBS often experience flare-ups of symptoms, which usually last between 2 to 4 days before improving or going away.
IBS can also cause symptoms in other parts of the body, such as:
- Lower back pain
- Muscle and joint pain
- Tiredness
- Nausea
- Headache
- Belching
- Bad breath
- Urinary urgency and frequency
What Causes IBS?
The cause of IBS (irritable bowel syndrome) is unknown but it is believed to be related to problems with brain-gut interaction, that is, how the brain and gut work together.
Different factors may play a role in causing IBS, including:
- Genetics
- Bacterial infections in the digestive tract
- Small intestinal bacterial overgrowth (SIBO)
- Food intolerances or sensitivities
- Abnormality of how the muscles move food through the digestive tract
- Digestive organs that are very sensitive to pain
- Problems with the immune system
- Problems with how the central nervous system controls the digestive system
- Unusual response to infection
- Stressful or difficult early life events, such as physical or sexual abuse
- Mental disorders such as depression, anxiety, and somatic symptom disorder
Some people with irritable bowel syndrome (IBS) have specific trigger foods that can cause or worsen their symptoms. Doctors may recommend IBS patients keep a food diary to note when symptoms occur. If certain foods aggravate symptoms, avoid those foods.
How Is IBS Diagnosed?
IBS (irritable bowel syndrome) is diagnosed first with a patient history and a physical exam. Other tests that may be used to diagnose IBS or rule out other conditions include:
- Blood tests to check for anemia, infection, and digestive diseases
- Stool tests to check for blood in the stool or other signs of infections or diseases
- Hydrogen breath test to check for small intestinal bacterial overgrowth (SIBO) or problems with carbohydrate digestion, such as lactose intolerance
- Upper GI endoscopy with a biopsy to check for celiac disease
- Colonoscopy to check for colon cancer or inflammatory bowel disease (IBD)
What Is the Treatment for IBS?
IBS (irritable bowel syndrome) is treated with changes diet and lifestyle, medications, probiotics, and therapy.
Dietary changes may include:
Lifestyle changes may include:
- Increasing physical activity
- Practicing stress reduction techniques
- Meditation
- Breathing exercises
- Yoga
- Tai Chi
- Getting adequate sleep
Medications used to treat IBS with diarrhea may include:
- Loperamide (Imodium)
- Rifaximin (Xifaxan)
- Eluxadoline (Viberzi)
- Alosetron (Lotronex), only for women to be used with special warnings and precautions
Medications used to treat IBS with constipation may include:
Other medications used to treat abdominal pain associated with IBS may include:
- Antispasmodics
- Antidepressants
- Coated peppermint oil capsules
From 
https://share.upmc.com/2016/03/irritable-bowel-syndrome-high-fiber-diet/
https://www.nursingtimes.net/clinical-archive/gastroenterology/irritable-bowel-syndrome-19-02-2009/