Irritable bowel syndrome is a disorder characterized most commonly by cramping, abdominal pain, bloating, constipation, and diarrhea. However, symptoms can vary from person to person.
IBS causes a great deal of discomfort and distress, but it does not permanently harm the intestines and does not lead to a serious disease, such as cancer. Although IBS has been called by many names, including "colitis" and "spastic colon," there is no known link between IBS and inflammatory bowel diseases such as Crohn's disease or ulcerative colitis.
As many as one in five Americans has symptoms of IBS, making it one of the most common disorders diagnosed by doctors. It occurs more often in women than in men, and generally begins before the age of 35 in about 50 percent of people.
There is no known cause for IBS. One theory is that people with IBS have a colon or large intestine that is particularly sensitive and reactive to certain foods and stress. The immune system may also be involved. Most people can control their symptoms with diet, stress management, and prescribed medications. For some people, however, IBS can be disabling.
IBS is generally diagnosed on the basis of a complete history that includes a careful description of symptoms and a physical examination. There is no specific test for IBS, although stool sample testing, blood tests, x rays, and sigmoidoscopy or colonoscopy, and tissue biopsies may be performed to rule out other problems, such as inflammatory bowel diseases, which may share similar symptoms.
A diagnosis of IBS is based on negative test results plus a characteristic pattern of symptoms including how the frequency of abdominal pain or discomfort, when the pain starts and stops in relation to bowel function, and how bowel frequency and stool consistency have changed.
Because it's not clear what causes irritable bowel syndrome, treatment focuses on the relief of symptoms. In addition, since the triggers for IBS as well as the specific symptoms vary from person to person, the treatment plan must be tailored to each individual.
In most cases, people can cope with mild signs and symptoms of irritable bowel syndrome by learning to manage stress and making changes in diet and lifestyle. These are discussed in the following section. For individuals with moderate or severe IBS symptoms, the following treatments are commonly used:
Two medications for IBS exist.
Diet is critical to the healthy function of the GI tract and to the reduction of problematic symptoms An important first step is to identify foods that seem to trigger symptoms. Keeping a food journal can be an effective way to do this.
Dietary habits  that may decrease IBS symptoms include:
Exercise regularly. Exercise helps relieve depression and stress, stimulates normal contractions of your intestines and can help you feel better about yourself. If you've been inactive, start slowly and gradually increase the amount of time you exercise. If you have other medical problems, check with your doctor before starting an exercise program. But generally, light to moderate exercise is recommended for everyone with IBS.
Stress--feeling mentally or emotionally tense, troubled, angry, or overwhelmed--can stimulate colon spasms in people with IBS since the colon has many nerves that connect it to the brain.
Stress management  is an important part of treatment for IBS. Approaches that can be beneficial are:
This is a system of medicine that brings an integrative perspective to a scientific understanding of the body and the disease process. It focuses on common ways in which illness develops and healing happens. Functional medicine  offers a personalized approach that works on primary prevention and underlying causes for serious chronic disease instead of mere symptom management.
If you see a Functional Medicine practitioner for GI dysfunction, he or she will likely evaluate the balance of bacteria in your gastrointestinal system, the permeability of the gut, the levels of inflammation (in the whole body), your immune function, and stress level.
Treatments would vary, depending on what was found, but could include: rebalancing the gut bacteria, quieting inflammation by changing diet, eliminating problematic foods, adding adequate fiber and water, supplementing appropriate nutrients, addressing psychosocial issues, and encouraging stress reduction practices.
Typical doses for each botanical are indicated below.
However, you should talk with your healthcare provider before adding botanicals
to your health regimen and ask about the right dosage for you.
It is especially important to see a conventional medical provider about any change in bowel habits, unexplained weight loss, blood in the stools, increasing pain, or any limitation of your daily activities. The first step in an evaluation is to determine if you have a more serious disorder, such as cancer or inflammatory bowel disease.
As always, it is critical to let ALL your health care providers know what supplements and medications you are taking.
It is also critical to identify and monitor your symptoms to determine what treatments and practices actually improve your comfort and daily wellbeing. A common tool is a diet and symptom diary, which can be indispensible for optimizing your care, whether your treatment is conventional care, lifestyle changes, functional medicine, acupuncture , or botanicals  and supplements.
Irritable Bowel Syndrome & the MindBodySpirit Connection: 7 Steps for Living a Healthy Life with a Functional Bowel Disorder, Crohn's Disease, or Colitis by William B. Salt and Neil F. Neimark
Your Gut Feelings: A Complete Guide to Living Better with Intestinal Problems, by Henry D. Janowitz, MD
The New Eating Right for a Bad Gut : The Complete Nutritional Guide to Ileitis, Colitis, Crohn's Disease, and Inflammatory Bowel Disease by James Scala
Institute for Functional Medicine: www.functionalmedicine.org 
Mayo Clinic on IBS: http://www.mayoclinic.com/health/irritable-bowel-syndrome/DS00106 
National Center for Complementary and Alternative Medicine: Introduction to probiotics: http://nccam.nih.gov/health/probiotics/index.htm 
Medline Plus: Irritable Bowel http://www.nlm.nih.gov/medlineplus/irritablebowelsyndrome.html#cat4