Noninfectious Gastroenteritis

What noninfectious gastroenteritis means

Gastroenteritis means inflammation of the stomach (gastro) and intestines (entero). Most cases are infections, the familiar "stomach bug". The label noninfectious (or noninfective) is used when tests and the story point away from a germ. It is used in medical records and the ICD coding system (K52, "other noninfective gastroenteritis and colitis") as an umbrella term that covers several distinct causes.

The lining of the gut reacts to injury in only a few ways: it becomes inflamed, absorbs less water and nutrients, and secretes more fluid. That is why many different triggers produce the same core symptoms.

Symptoms

• watery or loose diarrhea, sometimes urgent
• cramping or aching belly pain
• nausea, and sometimes vomiting
• bloating and gas
• loss of appetite
• tiredness and, if fluid loss is large, dehydration

Fever is usually absent or mild, which is one clue that infection is less likely. Symptoms that are linked to meals, a medicine or a treatment schedule also point to a noninfectious cause.

Causes

Medicines

Drug-induced gastroenteritis is one of the most common types. Culprits include:

• NSAIDs such as ibuprofen, naproxen and aspirin, which can inflame and ulcerate the stomach and bowel (NSAID gastropathy)
• antibiotics, which upset gut bacteria. If diarrhea is severe, C. difficile infection must be ruled out
• metformin, magnesium-containing antacids and supplements, and laxatives
• chemotherapy and some targeted cancer drugs, including immune checkpoint inhibitors, which can cause immune colitis
• proton pump inhibitors and SSRIs, linked with microscopic colitis
• colchicine, and some heart and blood pressure medicines

Food allergy and intolerance

• Food allergy: an immune reaction, for example to milk, eggs, shellfish or nuts. Vomiting, cramps and diarrhea can come with hives or swelling within minutes to 2 hours.
• Food protein-induced enterocolitis (FPIES): a delayed allergy, mostly in infants, causing repeated vomiting 1 to 4 hours after a trigger food such as cow's milk, soy or rice.
• Lactose intolerance and fructose malabsorption: not allergies but a failure to digest certain sugars, causing gas, bloating and diarrhea.
• Celiac disease: an autoimmune reaction to gluten that damages the small intestine.

Eosinophilic gastroenteritis

A rare condition where a type of white blood cell (eosinophils) builds up in the wall of the stomach or intestine. It causes pain, nausea, diarrhea and sometimes swelling or blockage. It is often linked with allergies and asthma.

Radiation

Radiation therapy to the abdomen or pelvis, for example for prostate, cervical or bowel cancer, inflames the bowel lining. Acute radiation enteritis starts within the first few weeks of treatment and usually settles within weeks of finishing. A chronic form can appear months or years later.

Toxins and chemicals

Heavy metals, some mushrooms, plant toxins, excess alcohol and poisonings can all inflame the gut. Note that "food poisoning" from bacterial toxins (such as Staphylococcus aureus toxin) is usually grouped with infectious causes.

Microscopic colitis and other inflammatory conditions

• Microscopic colitis: chronic watery diarrhea, mostly in people over 50, especially women. The colon looks normal on colonoscopy, and only biopsies show the inflammation.
• Inflammatory bowel disease: Crohn's disease and ulcerative colitis cause longer-lasting inflammation, often with blood, weight loss and night-time symptoms.
• Ischemic colitis: reduced blood flow to the colon, usually in older adults, causing sudden cramping left-sided pain and bloody diarrhea.
• Graft-versus-host disease after a stem cell transplant.

Noninfectious vs infectious gastroenteritis

Diagnosis

The doctor will ask about every medicine and supplement you take, recent antibiotics, foods that trigger symptoms, travel, radiation or cancer treatment, and family history of bowel disease. Tests may include:

• stool tests to rule out infection, including C. difficile, and fecal calprotectin, which rises with gut inflammation
• blood tests: blood count, kidney function and electrolytes, inflammation markers and celiac antibodies
• allergy testing when a food allergy is suspected
• endoscopy or colonoscopy with biopsies, which are essential to diagnose microscopic colitis, eosinophilic disease and inflammatory bowel disease
• a trial of stopping a suspected medicine or food

Treatment

Rehydration

Replace lost fluids with water and an oral rehydration solution. Sports drinks are acceptable for adults with mild symptoms. Seek care if you cannot keep fluids down.

Remove the trigger

• Stop or switch a suspected medicine, but only after speaking with the doctor who prescribed it.
• Avoid foods that cause allergy or intolerance. Lactase tablets help lactose intolerance.
• Celiac disease needs a strict lifelong gluten-free diet.

Specific treatments

• Microscopic colitis: the steroid budesonide is the main treatment.
• Eosinophilic gastroenteritis: elimination diets and steroids.
• Radiation enteritis: a low-fiber diet during treatment and antidiarrheal medicines.
• Inflammatory bowel disease: anti-inflammatory and immune-modifying medicines from a gastroenterologist.

Over-the-counter loperamide can ease diarrhea in adults once infection and bloody diarrhea are ruled out. Follow the label dose and do not use it if you have a fever or blood in the stool.

Outlook

Most people improve quickly once the trigger is identified and removed. Food- and medicine-related cases often settle within days. Microscopic colitis responds well to treatment but can relapse. Chronic radiation enteritis and inflammatory bowel disease need long-term management.

Frequently asked questions

What is noninfectious gastroenteritis?

It is inflammation of the stomach and intestines caused by something other than an infection, such as a medicine, a food allergy or intolerance, radiation, toxins or an immune condition like microscopic colitis. It causes diarrhea, cramps and nausea but is not contagious.

Is noninfectious gastroenteritis contagious?

No. Because there is no virus or bacteria involved, it cannot pass from person to person. If people you live with or ate with are sick at the same time, an infectious cause or food poisoning is more likely.

How long does noninfectious gastroenteritis last?

It depends on the cause. Diarrhea from a food or a short medicine course often stops within a few days of removing the trigger. Radiation enteritis usually settles within weeks of finishing treatment. Microscopic colitis and other chronic causes can last months without treatment.

What medicines can cause noninfectious gastroenteritis?

Common causes are NSAIDs like ibuprofen, antibiotics, metformin, magnesium supplements and antacids, chemotherapy and immunotherapy drugs, colchicine and laxatives. Proton pump inhibitors and SSRIs are linked to microscopic colitis. Never stop a prescribed medicine without talking to your doctor first.

How do doctors know gastroenteritis is not infectious?

They use the history, such as lack of fever, no sick contacts and a link to food or medicines, plus stool tests that find no germ. When diarrhea lasts more than two weeks, blood tests and a colonoscopy with biopsies can identify noninfectious causes like microscopic colitis.