Symptoms & Causes of Gas in the Digestive Tract

In this section:

What are the symptoms of gas?

The most common gas symptoms include burping, passing gas, bloating, and pain or discomfort in your abdomen. Gas symptoms vary from person to person.


Burping, or belching, once in a while, especially during and after meals, is normal. If you burp a lot, you may be swallowing too much air and releasing it before the air enters your stomach.

Passing gas

Passing gas around 13 to 21 times a day is normal.1


Bloating is a feeling of fullness or swelling in your abdomen. Bloating most often occurs during or after a meal.

Pain or discomfort in your abdomen

You may feel pain or discomfort in your abdomen when gas does not move through your intestines normally.

When should I talk with a doctor about my gas symptoms?

You should talk with your doctor if

  • gas symptoms bother you
  • your symptoms change suddenly
  • you have other symptoms with gas—such as constipation, diarrhea, or weight loss

What causes gas?

Gas normally enters your digestive tract when you swallow air and when bacteria in your large intestine break down certain undigested foods. You may have more gas in your digestive tract if you swallow more air or eat certain foods.

Swallowed air

Everyone swallows a small amount of air when eating and drinking. You swallow more air when you

  • chew gum
  • drink carbonated, or fizzy, drinks
  • eat or drink too fast
  • smoke
  • suck on hard candy
  • wear loose-fitting dentures

Swallowed air that doesn’t leave your stomach by burping moves into your intestines and passes through your anus.

Stick of gum out of wrapper
Glass of soda with ice and straw
Set of four colorful hard candies
You swallow more air when you chew gum; drink carbonated, or fizzy, drinks; or suck on hard candy.

Bacteria in your large intestine

Your stomach and small intestine don’t fully digest some of the carbohydrates—sugars, starches, and fiber—in the food you eat. Undigested carbohydrates will pass to your large intestine, which contains bacteria. These bacteria break down undigested carbohydrates and create gas in the process.

What foods, drinks, or products cause gas?

A variety of foods, drinks, and products can cause gas. See the following table for examples.

Table 1. Examples of foods, drinks, and products that can cause gas
black beans
brussels sprouts
kidney beans
navy beans
pinto beans

Whole Grains
whole wheat
Milk Products
ice cream

Packaged Foods with Lactose
salad dressing
apple juice
pear juice
carbonated drinks
drinks with high-fructose corn syrup
fruit drinks (such as fruit punch)
Sugar-free Products with Sorbitol, Mannitol, or Xylitol

Dietary Supplements and Additives
certain types of fiber, such as inulin and fructo-oligosaccharide, that may be added to processed foods to replace fat or sugar fiber supplements

What conditions cause excess gas or increase gas symptoms?

Some conditions can cause you to have more gas than usual or have more symptoms when you have gas. These conditions include the following:

Small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth is an increase in the number of bacteria or a change in the type of bacteria in your small intestine. These bacteria can produce extra gas and may also cause diarrhea and weight loss. Small intestinal bacterial overgrowth is most often a complication of other conditions.


Irritable bowel syndrome (IBS) is a group of symptoms—including pain or discomfort in your abdomen and changes in your bowel movement patterns—that occur together. IBS can affect how gas moves through your intestines. You may also feel bloated due to increased sensitivity to normal amounts of gas.


Gastroesophageal reflux disease (GERD) is a chronic condition that occurs when stomach contents flow back up into your esophagus. People with GERD may burp a lot to relieve discomfort.

Problems digesting carbohydrates

Problems digesting carbohydrates that can lead to gas and bloating include

  • lactose intolerance, a condition in which you have digestive symptoms such as bloating, gas, or diarrhea after eating or drinking milk or milk products.
  • dietary fructose intolerance, a condition in which you have digestive symptoms such as bloating, gas, or diarrhea after consuming foods that contain fructose.
  • celiac disease, an immune disorder in which you cannot tolerate gluten, a protein found in wheat, rye, barley, and some products such as lip balm and cosmetics. If you have celiac disease, gluten damages the lining of your small intestine.

Conditions that affect how gas moves through your intestines

Conditions that affect how gas moves through your intestines can lead to problems with gas and bloating. These conditions include dumping syndrome, abdominal adhesions, abdominal hernias, and conditions that can cause an intestinal obstruction such as colon cancer or ovarian cancer.


Last Reviewed July 2016

This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.