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Gastric Bypass, Diarrhea and Smelly Gas

Many people experience some degree of diarrhea and smelly gas -- malodorous flatulence -- after gastric bypass surgery. This is especially common during the first few months as their bodies adjust and heal. Although these symptoms are usually manageable with dietary changes and over-the-counter medications, discuss your symptoms with your surgeon before making changes to your treatment plan.

Digestion After Surgery

Gastric bypass surgery helps you lose weight by altering the anatomy of your digestive system. Your stomach is smaller after the procedure and food passes more quickly through your digestive system. As a result, your body absorbs fewer nutrients and your shortened bowel produces more gas and odors than before surgery.

To minimize the stress on your digestive system, follow your surgeon's meal plan instructions carefully. According to a report published in the September 2008 issue of "Surgery for Obesity and Related Diseases," most surgeons instruct patients to progress slowly during the first 8 weeks from liquids to pureed and soft foods before adding small amounts of solid foods.

Early Postoperative Complications

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Watery diarrhea and very foul-smelling gas occurring within the first 2 or 3 months after surgery may be due to Clostridium difficile colitis, according to a February 2008 report by the "American Society for Metabolic & Bariatric Surgery." Other symptoms may include fever, cramps in the abdomen and loss of appetite. C. difficile infections are generally treated with the antibiotic metronidazole (Flagyl).

A common cause of hospital-related diarrhea, C. difficile is spread through contact with anything contaminated by an infected person's stools, according to the Centers for Disease Control and Prevention. Risk factors include hospitalization, a recent course of antibiotics or abdominal surgery, including gastric bypass.

Long-Term Dietary Considerations

Diarrhea and flatulence usually improve as your body adjusts after gastric bypass surgery. After the early postoperative period, you will begin to eat small amounts of high-protein, low-carbohydrate, low-fat foods that give you the nutrients you need while losing weight. However, certain foods -- such as meat, beans, wheat, dairy products and vegetables -- may cause flatulence and diarrhea long after your body has healed. Keeping a food and symptom diary can help you pinpoint the foods that may be causing the problem.

Dumping Syndrome

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Dumping syndrome frequently occurs in gastric bypass patients when they eat foods containing a large amount of sugar. The bowel responds to the high concentration of sugar by moving extra fluid into the digestive system. As a result, diarrhea often occurs within 30 to 60 minutes. Excess gas is also produced as bacteria feed on the sugar. Hormones are released during an occurrence of dumping syndrome, commonly resulting in dizziness, flushing, a drop in blood pressure and an increase in heart rate. Symptoms may range from mild to severe and generally last 1 to 2 hours.

Eating Habits

Certain eating habits can increase intestinal gas. Many surgeons advise patients to avoid activities such as drinking carbonated beverages, chewing gum or using a straw to prevent the introduction of excess air into the digestive system. Eating slowly and chewing your food thoroughly can improve digestion and may reduce excess intestinal gas.

Drinking liquids during meals can push foods through the digestive system too quickly. People who have undergone gastric bypass surgery are usually advised to stop all fluids before beginning to eat and to wait for roughly 30 minutes afterward before drinking again.

Over-the-Counter Medications and Supplements

Surgeons' guidelines vary, but many provide their patients with a list of over-the-counter remedies for symptoms related to their surgery. Your surgeon may suggest medications such as loperamide (Imodium) for diarrhea, simethicone (Gas-X) to reduce the amount of gas produced, and bismuth subgallate (Devrom) to reduce the bad odor of intestinal gas. Probiotic supplements may be helpful in managing symptoms after surgery because they replace natural digestive bacteria that can be lost during surgery or antibiotic treatment.


If you have abdominal pain, fever or other symptoms along with malodorous gas and diarrhea, contact your doctor immediately as you may have a complication that requires medical attention.