Left-sided colitis is a type of ulcerative colitis, a condition that causes inflammation in the colon. Left-sided colitis affects the left side of the colon and may lead to diarrhea, abdominal pain, and other symptoms.

Left-sided colitis produces symptoms similar to those of other types of ulcerative colitis (UC). Outside of surgery, it is not curable, but treatment can reduce symptoms.

Several treatment methods are available to those with the condition, but the treatment and management will vary from case to case.

Person walking outdoors while carrying a bagShare on Pinterest
Alba Vitta/Stocksy

Pain in the lower left abdomen can occur due to left-sided colitis, or distal ulcerative colitis. This form of ulcerative colitis affects only the last portion of the colon, known as the distal colon. The distal colon extends from the rectum up the colon and stops at the splenic flexure, which is the point where the colon bends.

Ulcerative colitis is a type of inflammatory bowel disease. It develops when an unusual response by the body’s immune system leads to inflammation in the intestinal tract.

This inflammation causes small ulcers to form in the lining of the colon. These ulcers create mucus and pus and can lead to other symptoms.

Left-sided colitis is a chronic condition. After receiving a diagnosis, a person usually continues to experience symptoms throughout their life. There is currently no known cure for ulcerative colitis.

Other causes of abdominal pain on the left side can include:

  • diverticulosis
  • diverticulitis of the colon
  • gas pain
  • ulcers

The symptoms of left-sided colitis are very similar to those of many other types of ulcerative colitis.

People with left-sided colitis may experience constipation.

These individuals may complain of feeling the constant need to have a bowel movement. This sensation is called tenesmus, and it occurs as a result of irritation and inflammation in the rectum. When people with ulcerative colitis do pass stool, it is usually a very small amount.

Other symptoms of ulcerative colitis include:

The stool may also have blood in it. Bloody stools can be an indicator of significant colon damage.

Anyone with blood in their stool may need medical care. More than just a small streak of blood may require emergency medical attention.

There is no single cause of ulcerative colitis, but there are many theories about why it occurs.

Researchers believe a number of factors may play a role. These include:

  • genetics
  • gut microbiome
  • an atypical immune response
  • environmental factors

Correctly diagnosing left-sided colitis is a critical step in its treatment. Doctors usually perform an examination called an endoscopy, in which they use a camera to create images of the inside of the colon.

The images that the endoscopy captures help the doctor look for signs of inflammation, such as redness, water retention, and other irregularities.

In left-sided colitis, signs of the condition will disappear once the camera goes beyond the splenic flexure. Doctors typically use this knowledge to differentiate between left-sided colitis and other forms of ulcerative colitis.

The treatment for left-sided ulcerative colitis can vary depending on a few different factors. The severity of the symptoms and how well a person responds to medications may alter their treatment options.


Medications are currently the first-line treatment for ulcerative colitis. Depending on where in the colon the symptoms appear, a doctor may recommend taking the medications in various forms.

After evaluating the severity of the symptoms, doctors typically prescribe one or more medications to treat the inflammation.

Medications for left-sided ulcerative colitis may include:

5-aminosalicylic acid

Aminosalicylates that contain 5-aminosalicylic acid (5-ASA) help reduce inflammation in the colon, making them an effective therapy for people with left-sided ulcerative colitis.

A 2019 review suggests that rectal 5-ASA therapy may be more effective than oral therapy in the treatment of left-sided colitis.


While 5-ASA is helpful in the majority of cases, some people do not respond well to it. In these instances, doctors use corticosteroids to help manage the inflammation.

People can often use oral corticosteroids alongside 5-ASA for a more effective treatment.


Immunosuppressant medications target proteins in the immune system that spark the inflammation in ulcerative colitis.


Biologics are medications that target an immune system protein called tumor necrosis factor (TNF) to reduce inflammation in the large intestine.

JAK inhibitors

Janus kinase inhibitors (JAK inhibitors) are a fast-acting type of medication that can block inflammation pathways in the body.

They are small compounds broken down by the digestive system before being absorbed into the bloodstream and traveling around the body.

Currently, two JAK inhibitors have been approved by the Food and Drug Administration (FDA) for the treatment of moderate to severe ulcerative colitis:

  • upadacitinib (Rinvoq) comes in a tablet and is used for the treatment of ulcerative colitis if one or more TNF blockers were used unsuccessfully or were poorly tolerated.
  • tofacitinib (Xeljanz) comes in a tablet and is also used for the treatment of ulcerative colitis.


Severe cases of colitis may require hospitalization. In the hospital, a person will likely receive intravenous medications and steroids to reduce symptoms.

In rare cases — typically those involving severe damage, inflammation, or bleeding in the affected area — doctors may recommend removing part of the colon.

Left-sided colitis may cause complications, including toxic megacolon and anemia.

Toxic megacolon is a frequent complication of inflammatory bowel disease that causes the colon to dilate as inflammation builds up. Symptoms include:

Toxic megacolon increases the risk of a ruptured colon. Doctors usually treat the condition with medications and intravenous (IV) fluids. They may sometimes recommend surgery.

Anemia can be a further complication of left-sided colitis, as losing blood from the inflamed intestines can lead to a low red blood cell count. Doctors may treat the condition with iron supplements or blood transfusions.

Many people make dietary and lifestyle changes to help manage left-sided colitis.

Most doctors will recommend eating a varied diet to support left-sided colitis treatment. Some people also find that a diet high in soluble fiber and low in refined carbs can help ease inflammation in the colon.

Researchers need to conduct more studies to verify whether any natural methods are effective for ulcerative colitis symptoms.

Some people use probiotics for ulcerative colitis to reduce symptoms. However, research reports that the quality of placebo-controlled evidence for probiotics improving symptoms is low to very low.

Some people find that acupuncture helps them manage symptoms, though research has not confirmed its effectiveness.

Other natural supplements and dietary choices that some people use for ulcerative colitis include:

People can discuss home remedies and alternative treatments for any kind of ulcerative colitis with a doctor.

Left-sided colitis can cause symptoms similar to those of other forms of ulcerative colitis. It is important to understand the difference between the types of colitis and how they may affect a person.

Ulcerative proctitis

Healthcare professionals often see ulcerative proctitis as the starting point for all forms of ulcerative colitis. It is common for people who develop ulcerative colitis to receive a diagnosis of ulcerative proctitis first.

The symptoms and discomfort of ulcerative proctitis tend to be mild and cause few complications.

Total colitis

Unlike left-sided colitis, total colitis affects the entire colon. It often causes severe abdominal pain, chronic diarrhea, and weight loss. Total colitis causes extensive bleeding and often leads to toxic megacolon.


Proctosigmoiditis affects the rectum and the sigmoid colon, which is the lowest segment of the colon and is close to the rectum.

People with proctosigmoiditis may have bloody diarrhea and a constant feeling of needing to use the bathroom. Moderate pain and cramps in the abdomen are also common.

Researchers still have much to learn about ulcerative colitis, including left-sided ulcerative colitis. Although there is no cure for the condition, many people can reduce their symptoms or enter remission with proper treatment.

Working directly with a doctor is the best way to create a manageable treatment plan and reduce the risk of complications.

Read this article in Spanish.