What is gas in the digestive tract?

Gas in your digestive tract is made of air and other gases. It is produced when:

• You swallow air.

• Some undigested foods are broken down by the good bacteria in your large intestine (colon) and produce gas in the process.

Everyone has gas. It may be painful and embarrassing, but it's not dangerous. Your body gets rid of gas by burping or by passing it through your anus (flatulence). Most people make about 1 to 4 pints of gas a day. It's common to pass gas about 14 times a day.

Most gas is made up of vapors that don't smell. These include carbon dioxide, oxygen, nitrogen, hydrogen, and sometimes methane. Bad smells happen when bacteria in your large intestine make gases that contain sulfur.

What causes gas in the digestive tract?

Gas in your digestive tract can be caused by two things:

• Swallowing air (aerophagia). This can happen when you eat or drink too quickly, chew gum, smoke, drink carbonated drinks, or wear loose dentures. Having postnasal drip can also cause it. Most air that you swallow leaves your stomach when you burp or belch. Some of the gas that is left is absorbed into your small intestine. A small amount goes into the large intestine. It's passed out through your anus.

• Breaking down of some undigested foods by good bacteria. These bacteria are found in the large intestine (colon). Carbohydrates (carbs) are nutrients found in sugar, starches, and fiber. Some carbs are not digested or absorbed in your stomach and small intestine. They go into your large intestine, where they are broken down into small parts by good bacteria. This process produces hydrogen and carbon dioxide. In some cases, it also makes methane gases. These gases are passed through your anus.

Who is at risk for gas in the digestive tract?

Some health problems can cause you to make more gas in your digestive tract. These include:

• Being lactose intolerant, which is being unable to digest sugar (lactose) in milk products.

• Irritable bowel syndrome, an intestinal problem.

• Inflammation in the intestines, such as inflammatory bowel disease.

• Stomach disorders such as peptic ulcer disease and heartburn or GERD (gastroesophageal reflux disease).

• Health problems that cause constipation.

• Gastroparesis, also called delayed gastric emptying. It slows or stops the movement of food from your stomach to your small intestine.

• Celiac disease is an illness caused by an immune reaction to eating foods containing gluten.

• Medicines (anticholinergics, opiates, calcium blockers, antidepressants) that affect how your stomach and intestines move food.

What are the symptoms of gas?

Each person’s symptoms may vary. The most common symptoms of gas are:

• Belching. Belching during or after meals is normal. But belching too often can be a problem. You may be swallowing too much air. And you may be letting the air out before it enters your stomach. Chronic belching may also mean that you have an upper GI (gastrointestinal) disorder. These may include peptic ulcer disease, GERD, or gastritis.

• Passing gas, or flatulence. Passing gas through the anus is called flatulence. It's normal to pass gas 14 to 23 times a day.

• Abdominal (belly) pain. Gas in your intestine may be painful. When it collects on the left side of your colon, the pain may seem like heart disease. When it collects on the right side of your colon, the pain may feel like gallstones or appendicitis.

• Abdominal bloating (distention). In most cases, this happens when the muscles of your intestine don’t move or contract in the normal way. This type of problem is called an intestinal motility disorder. It can make you feel and look bloated from your belly being swollen with gas.

Other health issues that may cause abdominal bloating include:

• Crohn's disease, Celiac disease, colon cancer, or any disease that causes a blockage in your intestine. Internal hernias or scar tissue (adhesions) from surgery can also cause bloating.

• Fatty foods can delay stomach emptying and cause bloating and discomfort, but they may not cause too much gas.

• Small intestinal bacterial overgrowth. This can also cause you to have trouble absorbing nutrients and cause you to lose weight.

There are a few rare, chronic gas diseases that cause belching. One of these is:

• Meganblase syndrome. This causes chronic belching. It happens after eating big, heavy meals. You swallow a large amount of air and have a big bubble of gas in your stomach. This makes you feel very full. You may have trouble breathing. It can also feel like a heart attack.

The symptoms of gas may look like other health problems. Always see your provider to be sure.

How is gas in the digestive tract diagnosed?

Many times, you will not need testing for symptoms of intestinal gas. In some cases, you may have gas symptoms because of a serious health problem. Always see your health care provider to be sure.

Your provider will look at your past health and give you a physical exam. The following tests may also be done:

• Abdominal X-ray. An X-ray machine sends a beam of radiation through the belly. The image is recorded on special film or a computer.

• Colonoscopy. This test checks for colorectal cancer, polyps, and other colon disease. A long, flexible, lighted tube (colonoscope) is inserted in through your rectum and up into your colon. The provider uses the tube to see the lining of the colon and to take a tissue sample (biopsy). They may also be able to fix some problems that are found. A colonoscopy looks at the entire length of the large intestine. This test can often help find abnormal growths, inflamed tissue, ulcers, and bleeding. Colonoscopy is recommended if you are age 45 or older, or maybe even earlier if you have a family history of colorectal cancer.

• Food diary. You may be asked to keep a diary of what you eat and drink for a certain time period and record your symptoms.

• Sigmoidoscopy. This test checks the inside of the last part of your large intestine. It may find what is causing diarrhea, belly pain, constipation, abnormal growths, and bleeding. A short, flexible, lighted tube (sigmoidoscope) is put into your intestine through the rectum. The tube blows air into your intestine to make it swell. This makes it easier to see inside.

• Upper endoscopy (EGD). A flexible tube with a light is passed down your mouth to look at your esophagus, stomach, and small intestine (duodenum).

• Upper GI (gastrointestinal) series or barium swallow. If you have chronic belching, you may be swallowing too much air. If your provider is concerned about other reasons for your symptoms, you may need testing. This test checks the organs at the beginning of your digestive system. It checks the esophagus, stomach, and the first part of the small intestine (duodenum). You will swallow a metallic fluid called barium. Barium coats the organs so that they can be seen on an X-ray. 

• Esophageal manometry and impedance test. This test can show how your esophagus contracts and if you are swallowing and belching excess air.

• Blood test. Depending on your symptoms, a blood test for celiac disease may be done.

How is gas in the digestive tract treated?

Your health care provider will make a care plan for you based on:

• Your age, overall health, and past health.

• How serious your case is.

• How well you handle certain medicines, treatments, or therapies.

• If your condition is expected to get worse.

• Your expectations and what you would like to do.

You can reduce some of your gas pain by:

• Changing your diet, eating, and drinking habits. Don’t have soda or other carbonated drinks. Don’t take any foods that might give you gas. Lactose-free dairy products and a low FODMAP diet are often helpful.

• Taking medicines. There are many over-the-counter medicines for gas. Ask your provider or pharmacist for suggestions. Talk with your health care provider before taking herbal supplements, probiotics, or alternative medicines or doing alternative medical practices.

• Reducing the amount of air you swallow. Don’t chew gum or suck on hard candies.

  • Take your time to eat more slowly and, when possible, sit down to eat instead of eating on the run.

  • Avoid talking while eating or drinking.

  • Avoid using straws while drinking from bottles or cans.

  • If you wear dentures, have your dentist make sure they fit well.

• Depending on the cause of your gas, you may get prescription medicines.

Can gas in the digestive tract be prevented?

You can’t stop all gas in the digestive tract. But you can reduce the amount of gas made in your digestive system. Don’t take foods or drinks that seem to give you more gas. And follow your health care provider’s advice.

When should I call my doctor?

In most cases, having gas in your digestive tract is not serious. But you should call your health care provider if:

• Your symptoms increase or change.

• You have new symptoms such as constipation, cramps, diarrhea, or weight loss.

• You are vomiting.

• You have blood in the stool or black, tarry stool.

• You have pain that does not go away.

• Treatments you tried before don’t work now.

Key points about gas in the digestive tract

• Everyone has gas in their digestive tract.

• Gas in your digestive tract is created when you swallow air. It's also caused by the breakdown of some foods by good bacteria in your colon.

• Your body gets rid of gas by burping or by passing it through your anus.

• Most foods with carbohydrates cause gas.

• The most common symptoms of gas are burping, passing gas, belly or abdominal bloating, and abdominal pain.

• You can often reduce gas pain by changing your diet, taking medicines, and reducing how much air you swallow.

Next steps

Here are some tips to help you get the most from a visit to your health care provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis. Note any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you don't take the medicine or have the test or procedure.

• If you have a follow-up visit, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.