Left-sided ulcerative colitis (UC) can cause pain in your abdomen or rectum, along with other symptoms. Treatment typically involves medication to lower inflammation.

Ulcerative colitis (UC) is a condition that causes your colon or parts of it to become inflamed.

In left-sided UC, inflammation occurs only on the left side of your colon. It’s also known as distal UC.

In this form of UC, inflammation stretches from your rectum to your splenic flexure. The splenic flexure is the name of a bend in the colon, near your spleen. It’s located on the left side of the abdomen.

Other types of UC include:

  • proctitis, in which inflammation is limited to the rectum
  • pancolitis, which causes inflammation throughout the whole colon

Generally, the more of your colon that’s affected, the more symptoms you experience.

Diarrhea is the most common symptom of UC. Sometimes, your stool may also have streaks of blood.

Damage and irritation to your rectum can cause you to feel like you’re constantly needing to have a bowel movement. However, when you go to the bathroom, the amount of stool is usually small.

Other symptoms of UC include:

  • abdominal or rectal pain
  • fever
  • weight loss
  • constipation
  • rectal spasms

Bloody stools can be a sign of serious damage to the colon. Blood in your stool may be bright or dark red.

If you see blood in your stool, call your doctor. If there’s more than a small amount of blood, seek emergency medical attention.

UC is an autoimmune disorder that causes inflammation in your colon. However, the exact triggers are unknown.

According to 2022 research, UC is associated with several factors that may trigger an irregular immune response. These include:

  • genetics
  • irregular immune response
  • microbiome
  • environmental factors

Your doctor may identify the type of colitis you have with a procedure known as a colonoscopy. In this procedure, they use lighted cameras to view the inner lining of your colon.

Your doctor can identify the degree of inflammation by looking for:

  • redness
  • edema
  • ulcers
  • atrophy (worsened function)
  • bleeding
  • other irregularities in the lining of the colon

If you have left-sided colitis, the lining of your colon will start to look usual again once your doctor has navigated past the splenic flexure.

Treatment recommendations for UC can change depending on how much of your colon is affected. But your doctor may prescribe the following treatments:

5-ASA medication

A medication known as 5-aminosalicylic acid, or 5-ASA, is a common treatment for UC.

5-ASA medications can be taken orally or applied topically. They can lower the occurrence of inflammation in your bowel.

5-ASA is also available as a suppository or enema. If you have left-sided UC, your doctor will likely prescribe an enema. A suppository might not reach enough of the affected area.

Oral corticosteroids

If your symptoms don’t respond to 5-ASA, your doctor may prescribe oral corticosteroids. Oral corticosteroids can lower inflammation. They’re often successful when taken with 5-ASA medications.

Biologics and immunomodulators

If your symptoms are moderate to severe, your doctor may prescribe a biologic drug. These are antibodies that target inactivated immune system proteins known to cause UC inflammation.

They’re a long-term treatment that can help prevent flare-ups.

Current guidelines suggest that the following options may be the most effective:

Another class of drugs, known as immunomodulators, may also help. A doctor may prescribe these alongside other options. They include:

Long-term treatment can lower the risk of a flare and lessen the need for steroid medications, which can have adverse effects.

JAK inhibitors

Janus kinase (JAK) inhibitors are small compounds that are broken down in the digestive system. They’re then absorbed into the bloodstream.

They work by blocking pathways of inflammation in the body. They act faster than some other medications like thiopurines.

The Food and Drug Administration (FDA) has approved two JAK inhibitors for the treatment of moderate to severe UC:

  • tofacitinib (Xelianz), which is available in tablet form
  • upadacitinib (Rinvoq), which is available in tablet form for the treatment of UC when one or more TNF blockers have been used and were unsuccessful or poorly tolerated


In severe, rare instances, you may require hospitalization to treat your symptoms. If you’re hospitalized, you may receive intravenous (IV) steroids or other IV medications that can help stabilize your condition.

Sometimes, your doctor may recommend removing the affected portion of your colon. This is usually recommended only if you have severe bleeding or the inflammation has caused a small hole in your colon.

More research needs to be done on the benefits of natural treatments and remedies for UC. But there are some options that may help you manage the condition.

These include:

Talk with your doctor before starting any of these treatments to make sure they’re safe and right for you.

What is the difference between left-sided colitis and extensive colitis?

In left-sided UC, the inflammation is confined to only one side of the colon, whereas pancolitis, also called extensive colitis, affects the entire colon.

What is the difference between left-sided UC and proctitis?

Proctitis is an inflammation of the inner lining tissue of the rectum, which is located close to the anus or just above it.

What causes inflammation in the left colon?

Other than left-sided colitis, pain in the left colon can also be caused by ischemic colitis. This is when not enough blood flows into the colon. Another cause can be an infection.

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