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Colitis is a condition in which there is inflammation of the colon. The colon is the major part of the large intestine, which is located in the belly. The intestine is a tube shaped structure that is part of the digestive tract. The large intestine absorbs moisture from the matter that is left after it is digested in the small intestine, and excretes the waste from the anus. Excrete means to release from the body as waste. Colitis can be chronic, meaning it has lasted a long time. Colitis can also be acute, meaning it has occurred suddenly.


Signs and symptoms of colitis include fever, weight loss, pain in the belly, bleeding, destruction of the tissue lining of the intestine, and severe diarrhea (usually with blood and mucus). Mucus is a type of thick, slippery fluid released by the body.

There are a few conditions that are characterized by symptoms similar to colitis (see above for symptoms). One condition is inflammation of the rectum (the last part of the large intestine). Cancer of the intestine can have symptoms similar to colitis. Cancer is a group of diseases in which symptoms are due to an abnormal and excessive growth of cells in one of the body organs or tissues.

Diverticular disease can also cause an area of the colon to be irritated. In this case, diverticular disease refers to the presence of diverticuli (small sacs caused by the inner lining of the intestines sticking out) and any symptoms that are caused by their presence. Some sexually transmitted diseases can cause colitis. An example would be gonorrhea, which is a common bacterial infection transmitted during intercourse.


If a patient has severe diarrhea, the doctor will usually tell the patient to stop eating and to only drink clear liquids (liquids you can clearly see through, such as water). If despite this, the diarrhea continues for more than five days, the doctor will usually send a sample of feces to be examined for the presence of bacteria and parasites. A parasite is any organism that lives in or on another living being, gains an advantage by doing so, but causes disadvantage to the being it is living on.

Another way that doctors assess for colitis is by sticking one of their fingers into the patient's rectum. If this examination is normal and there is no infection present, the rectum and colon will be examined with a viewing device known as a sigmoidoscope. The purpose of this examination is to see if there is any inflammation or ulcers (open sores) in the lining of the rectum or colon. A tissue sample can be taken from any areas of inflammation or open sores and examined under a microscope to look for changes that are consistent with colitis. Another technique used for diagnosing colitis is a barium enema of the colon. This technique involves placing a tube inside the patient's rectum (the last part of the large intestine) and inserting barium (a metallic chemical) into the rectum through the tube. X-rays are then taken that produces pictures of the colon. The doctor looks for any areas of inflammation or narrowing in the large intestine. See the first section for a description of the colon and large intestine.


There are many possible causes of colitis, however, most of these causes are unknown. A common cause would be an infection by a virus, bacteria, or an amoeba. An amoeba is a single-celled parasite. A parasite is any organism that lives in or on another living being, gains an advantage by doing so, but causes disadvantage to the being it is living on. A type of bacteria that can cause colitis is campylobacter. This bacteria makes poisons that irritate the lining of the intestine. The intestine is a tube shaped structure that is part of the digestive tract. Other types of bacteria can cause an infection in the lining of the colon, causing colitis.

Antibiotics, which are drugs used to treat infections caused by bacteria, can cause a form of colitis. This is especially true if the antibiotics are taken longer than 2 weeks. The reason for this is that the antibiotics can kill "good" bacteria that normally lives in the intestine. These "good" bacteria usually control another type of bacteria known as Clostridium Difficile (often referred to as C. Difficile or C. Diff). When these "good" bacteria are killed it can no longer control the amount of "bad" bacteria (Clostridium Difficile) that is present. When the amount of Clostridium Difficile increases, it can make an irritating poison to the colon.

Another cause of colitis is Crohn's disease, in which any part of the digestive tract becomes inflamed. A more rare cause of colitis is decreased blood supply to the wall of the intestine. This usually occurs in the elderly and is usually due to a narrowing of the blood vessels. The term "ulcerative colitis" refers to long-term inflammation and open sores in the lining of the colon and rectum.

Most of the time, infections that cause colitis go away without treatment. In some cases, antibiotics are used to treat the condition. Different bacteria are treated with different antibiotics. If the colitis is caused by decreased blood supply to the wall of the intestine, surgery is used to remove the damaged section of the colon.

Crohn's disease and ulcerative colitis (see the last paragraph for a description) are treated with corticosteroid drugs because these are drugs that reduce inflammation. The drugs are usually taken by mouth unless the condition has occurred suddenly, in which case the drugs are given through a tube that is placed in the rectum. Crohn's disease and ulcerative colitis can also be treated with other drugs and/or a special diet and additional vitamins. Surgery does not usually cure these diseases and is usually used to treat complications.


Colitis comes from the Greek word "kolon" meaning "large intestine," and the Greek word "itis" meaning "inflammation." Put the two words together and you have "large intestine inflammation."