A review published in Current Gastroenterology Reports in February 2015 examined the role of cannabinoids in the treatment of gastrointestinal symptoms like nausea, vomiting, and visceral pain and found that certain targeted cannabinoid therapies may be useful in GI disease/disorder management.

Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the colon and small intestine. Crohn’s disease and ulcerative colitis are the principal types of inflammatory bowel disease. It is important to note that not only does Crohn’s disease affect the small intestine and large intestine, it can also affect the mouth, esophagus, stomach and the anus whereas ulcerative colitis primarily affects the colon and the rectum. Source

In the past, Cannabis preparations have been considered new promising pharmacological tools in view of their anti-inflammatory role in IBD as well as other gut disturbances. However, their use in the clinical therapy has been strongly limited by their psychotropic effects. CBD is a very promising compound since it shares the typical cannabinoid beneficial effects on gut lacking any psychotropic effects. For years, its activity has been enigmatic for gastroenterologists and pharmacologists, but now it is evident that this compound may interact at extra-cannabinoid system receptor sites, such as peroxisome proliferator-activated receptor-gamma. This strategic interaction makes CBD as a potential candidate for the development of a new class of anti-IBD drugs. Source

Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a group of symptoms—including abdominal pain and changes in the pattern of bowel movements without any evidence of underlying damage. These symptoms occur over a long time, often years. It has been classified into four main types depending on if diarrhea is common, constipation is common, both are common, or neither occurs very often (IBS-D, IBS-C, IBS-M, or IBS-U respectively). IBS negatively affects quality of life and may result in missed school or work. Disorders such as anxiety, major depression, and chronic fatigue syndrome are common among people with IBS.

The causes of IBS are not clear. Theories include gut–brain axis problems, small intestinal bacterial overgrowth, genetic factors, food sensitivity, and gut motility problems. Onset may be triggered by an intestinal infection, or stressful life event. IBS is a functional gastrointestinal disorder. Diagnosis is based on signs and symptoms in the absence of worrisome features. Worrisome features include onset at greater than 50 years of age, weight loss, blood in the stool, or a family history of inflammatory bowel disease. Other conditions that may present similarly include celiac disease, microscopic colitis, inflammatory bowel disease, bile acid malabsorption, and colon cancer.

There is no cure for IBS. Treatment is carried out to improve symptoms. This may including dietary changes, medication, probiotics, and counseling. Dietary measures include increasing soluble fiber intake, a gluten free diet, or a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP). The medication loperamide may be used to help with diarrhea while laxatives may be used to help with constipation. Antidepressants may improve overall symptoms and pain. Patient education and a good doctor–patient relationship are an important part of care.

Ulcerative Colitis

Ulcerative colitis (UC) is a long-term condition that results in inflammation and ulcers of the colon and rectum. The primary symptom of active disease is abdominal pain and diarrhea mixed with blood. Weight loss, fever, and anemia may also occur. Often symptoms come on slowly and can range from mild to severe. Symptoms typically occur intermittently with periods of no symptoms between flares. Complications may include megacolon, inflammation of the eye, joints, or liver, and colon cancer.

The cause of UC is unknown. Theories involve immune system dysfunction, genetics, changes in the normal gut bacteria, and environmental factors. Rates tend to be higher in the developed world with some proposing this to be the result of less exposure to intestinal infections, or a Western diet and lifestyle. The removal of the appendix at an early age may be protective. Diagnosis is typically by colonoscopy with tissue biopsies. It is a kind of inflammatory bowel disease (IBD) along with Crohn’s disease and microscopic colitis.

Dietary changes may improve symptoms. Several medications are used to treat symptoms and bring about and maintain remission. These include aminosalicylates such as sulfasalazine, steroids, immunosuppressants such as azathioprine, and biological therapy. Removal of the colon by surgery may be necessary if the disease is severe, does not respond to treatment, or if complications such as colon cancer develop. Removal of the colon and rectum can cure the disease.

Crohn’s Disease

Crohn’s disease (CD) is an inflammatory bowel disease. It causes inflammation of the lining of the digestive tract, which can lead to abdominal pain, cramping, severe diarrhea, fatigue, and general reduction in well-being. Inflammation caused by Crohn’s disease can involve different areas of the digestive tract in different people. The inflammation caused by Crohn’s disease often spreads deep into the layers of affected bowel tissue. Crohn’s disease can be both painful and debilitating, and sometimes may lead to life-threatening complications. While there’s no known cure for Crohn’s disease, therapies can greatly reduce its symptoms and even bring about long-term remission. With treatment, many people with Crohn’s disease are able to function well.
In humans, cannabis has been used to treat a number of gastrointestinal problems, including anorexia, emesis, abdominal pain (including Crohn’s and ulcerative colitis), diarrhea, and diabetic gastroparesis. Cannabinoids decrease cellular inflammation in the gut, and are therefore ideal targets for inflammatory bowel diseases.
In an observational study in 30 patients with Crohn’s disease (CD), this research group found that medical cannabis was associated with improvement in disease activity and reduction in the use of other pharmaceutical medications. In a more recent placebo-controlled study in 21 chronic CD patients, the same research group showed a decrease in the CD symptoms (10 of 11 subjects on cannabis compared to 4 of 10 on placebo). Complete remission was achieved in 5 of 11 subjects in the cannabis group and 1 of 10 in the placebo group.