The mucosa is a membrane that lines the inside of your digestive tract. Erythematous means redness. So, having erythematous mucosa means the inner lining of your digestive tract is red.

Erythematous mucosa isn’t a disease. It’s a sign that an underlying condition or irritation has caused inflammation, which has increased blood flow to the mucosa and made it red.

The term erythematous mucosa is mainly used by doctors to describe what they find after examining your digestive tract with a lighted scope inserted through your mouth or rectum. The condition associated with it depends on the part of your digestive tract affected:

Symptoms of erythematous mucosa vary depending on where the inflammation is located. The following locations are most commonly affected:

Stomach or antrum

Gastritis usually affects your entire stomach, but sometimes it only affects the antrum — the lower part of the stomach. Gastritis can be short-term (acute) or long-term (chronic).

Symptoms of acute gastritis may include:

  • mild discomfort or full feeling in the upper left side of your abdomen after eating
  • nausea and vomiting
  • loss of appetite
  • heartburn or indigestion, which is a burning, dull pain

If the irritation is so bad it causes an ulcer, you may vomit blood. Sometimes, though, acute gastritis has no symptoms.

Most people with chronic gastritis have no symptoms, either. But you can get anemia from B-12 deficiency because your stomach can’t secrete the molecule needed to absorb B-12 anymore. You may feel fatigued and dizzy and look pale if you’re anemic.

Colon

Your large intestine is also called your colon. It connects your small intestine to your rectum. The symptoms of colitis may vary a little depending on the cause, but general symptoms include:

  • diarrhea that may be bloody and is often severe
  • abdominal pain and cramping
  • abdominal bloating
  • weight loss

The two most common inflammatory bowel diseases (IBDs), Crohn’s disease and ulcerative colitis, can cause inflammation in other parts of your body besides your colon. These include:

  • your eyes, which causes them to be itchy and watery
  • your skin, which causes it to form sores or ulcers and become scaly
  • your joints, which causes them to swell and become painful
  • your mouth, which causes sores to develop

Sometimes fistulas form when the inflammation goes completely through your intestinal wall. These are abnormal connections between two different parts of your intestine — between your intestine and your bladder or vagina, or between your intestine and the outside of your body. These connections allow stool to move from your intestine to your bladder, vagina, or outside of your body. This can lead to infections and stool coming out of your vagina or skin.

Rarely, colitis can be so bad that your colon ruptures. If this happens, stool and bacteria can get into your abdomen and cause peritonitis, which is inflammation of the lining of your abdominal cavity. This causes severe abdominal pain and makes your abdominal wall hard. It’s a medical emergency and can be life-threatening. Work with your doctor to manage your symptoms to avoid this complication.

Rectum

Your rectum is the last part of your digestive tract. It’s a tube connecting your colon to the outside of your body. Symptoms of proctitis include:

  • feeling pain in your rectum or lower left abdomen, or when you have a bowel movement
  • passing blood and mucus with or without bowel movements
  • feeling like your rectum is full and you frequently have to have a bowel movement
  • having diarrhea

Complications can also cause symptoms, such as:

  • Ulcers. Painful openings in the mucosa can occur with chronic inflammation.
  • Anemia. When you continually bleed from your rectum, your red blood cell count can go down. This can make you feel tired, unable to catch your breath, and dizzy. Your skin may look pale as well.
  • Fistulas. These can form from the rectum just like from your colon.

Stomach or antrum

Acute gastritis can be caused by:

  • nonsteroidal anti-inflammatory drugs (NSAIDS)
  • aspirin
  • bile refluxing from the intestine
  • Helicobacter pylori (H. pylori) and other bacterial infections
  • alcohol
  • Crohn’s disease

Chronic gastritis is usually caused by the H. pylori infection. About one out of five Caucasians have H. pylori, and over half of African Americans, Hispanics, and older people have it.

Colon

Several things can cause colitis, including:

  • Inflammatory bowel disease. There are two kinds, Crohn’s disease and ulcerative colitis. They’re both autoimmune diseases, which means your body is improperly attacking itself.
  • Diverticulitis. This infection happens when little sacs or pouches created by the mucosa stick through weak areas in the colon wall.
  • Infections. These can come from bacteria in contaminated food, such as salmonella, viruses, and parasites.
  • Antibiotics. Antibiotic-associated colitis usually happens after you take strong antibiotics that kill all the good bacteria in your intestine. This allows a bacterium called Clostridium difficile, which is resistant to the antibiotic, to take over.
  • Lack of blood flow. Ischemic colitis occurs when the blood supply to part of your colon has been reduced or stopped completely, so that part of the colon starts to die because it’s not getting enough oxygen.

Rectum

Some of the most common causes of proctitis are:

  • the same two types of inflammatory bowel disease that can affect the colon
  • radiation treatments to your rectum or prostate
  • infections:
    • sexually transmitted diseases such as chlamydia, herpes, and gonorrhea
    • bacteria in contaminated food such as salmonella
    • HIV

In infants, protein-induced proctitis, which is associated with drinking soy or cow’s milk, and eosinophilic proctitis, which is caused by an excess of white cells called eosinophils in the lining, can occur.

Diagnosis of erythematous mucosa of any part of your digestive tract is usually confirmed by examining biopsies of the tissue obtained during an endoscopy. In these procedures, your doctor uses an endoscope — a thin, lighted tube with a camera — to look through to see inside your digestive system.

A small piece of the erythematous mucosa can be removed through the scope and looked at under a microscope. When your doctor uses this, you’ll usually be given medicine that makes you sleep through it and not remember the procedure.

Stomach or antrum

When your doctor looks at your stomach with a scope, it’s called an upper endoscopy. The scope is inserted through your nose or mouth and gently moved forward into your stomach. Your doctor will also look at your esophagus and the first part of your small intestine (the duodenum) during the procedure.

Gastritis can usually be diagnosed based on your symptoms and history, but your doctor may run some other tests to be sure. These include:

  • a breath, stool, or blood test can confirm if you have H. pylori
  • an endoscopy can allow your doctor to look for inflammation and take a biopsy if any area looks suspicious or to confirm you have H. pylori

Colon

When your doctor looks at your rectum and colon, it’s called a colonoscopy. For this, the scope is inserted into your rectum. Your doctor will look at your entire colon during this procedure.

A smaller lighted scope called a sigmoidoscope can be used to exam just the end of your colon (the sigmoid colon), but a colonoscopy is usually performed to look at your entire colon in order to take biopsies of abnormal areas or samples to use to look for infection.

Other tests that your doctor may do include:

  • blood tests to look for anemia or markers of an autoimmune disease
  • stool tests to look for infections or blood that you can’t see
  • a CT or MRI scan to look at the entire intestine or look for a fistula

Rectum

A sigmoidoscope can be used to examine your rectum to look for proctitis and get biopsy tissue. A colonoscopy may be used if your doctor wants to look at your whole colon and your rectum. Other tests may include:

  • blood tests for infections or anemia
  • a stool sample to test for infection or diseases transmitted sexually
  • a CT scan or MRI if your doctor suspects a fistula exists

H. pylori can cause chronic gastritis, which can lead to ulcers and sometimes to stomach cancer. Studies suggest your risk of stomach cancer may be three to six times higher if you have H. pylori than if you don’t, but not all doctors agree with these numbers.

Because of the increased risk, it’s important that H. pylori is treated and eradicated from your stomach.

Ulcerative colitis and Crohn’s disease increase your risk of colon cancer beginning after you’ve had them for about eight years. At that point, your doctor will recommend you have a colonoscopy every year so cancer is caught early if it develops. If your ulcerative colitis only affects your rectum, your cancer risk isn’t increased.

Treatment varies depending on the cause, but the first step is always to stop anything that might be causing or worsening it such as alcohol, NSAIDS or aspirin, a low-fiber diet, or stress. The inflammation improves quickly after the irritant is removed.

Stomach or antrum

Several medications that reduce your stomach acid are available by prescription and over the counter. Reducing stomach acid helps the inflammation heal. These medicines may be recommended or prescribed by your doctor:

Specific treatments include:

  • If the cause is NSAIDS or aspirin: These medicines should be stopped and one or more of the above medications taken.
  • For an H. pylori infection: You’ll be treated with a combination of antibiotics for 7 to 14 days.
  • B-12 deficiency: This deficiency can be treated with replacement shots.
  • If a biopsy shows precancerous changes: You’ll probably undergo endoscopy once a year to look for cancer.

Other treatments include:

  • Reducing or eliminating alcohol, which reduces the irritation your stomach lining is exposed to.
  • Avoiding foods that you know upset your stomach or cause heartburn, which also reduce stomach irritation and may help your symptoms.

Colon

Treatment of colitis is based on the cause:

  • Inflammatory bowel disease is treated with medications that decrease inflammation and suppress your immune system. Changing your diet and decreasing your stress level can also help reduce symptoms or keep them away. Sometimes surgical removal of severely damaged parts of your colon is necessary.
  • Diverticulitis is treated with antibiotics and a diet that contains an adequate amount of fiber. Sometimes it’s severe enough to require you be hospitalized and treated with IV antibiotics and a liquid diet to rest your colon.
  • Bacterial infections are treated with antibiotics.
  • Viral infections are treated with antivirals.
  • Parasites are treated with antiparasitics.
  • Antibiotic-associated colitis is treated with antibiotics that Clostridium difficile isn’t resistant to, but sometimes it’s very hard to get rid of it completely.
  • Ischemic colitis usually is treated by fixing the cause of the reduced blood flow. Often, the damaged colon must be surgically removed.

Rectum

  • Inflammatory bowel disease in the rectum is treated the same as in the colon, with medication and lifestyle changes.
  • Inflammation caused by radiation therapy doesn’t require treatment if it’s mild. Anti-inflammatory medications can be used if it’s more severe.
  • Infections are treated with antibiotics or antivirals, depending on the cause.
  • The conditions affecting infants are treated by determining which foods and beverages are causing the problem and avoiding them.

The symptoms of erythematous mucosa due to inflammation can be mild or severe and are different depending on which part of your digestive tract is involved. Effective ways of diagnosing and treating these conditions exist.

It’s important that you see your doctor if you have the symptoms of gastritis, colitis, or proctitis. That way, your condition can be diagnosed and treated before it becomes too severe or you develop complications.